Self Help Manual Of 1 Story Buildings
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MICROFICHE REFERENCE LIBRARY A project of Volunteers in Asia Self-Heln Construction of l-Storv Peace Corps ATFD Manual M-6 by: Peter Buildins Gallant Published by: Peace Corps Information Collection and Exchange 806 Connecticut Avenue, NW Washington, DC 20525 USA Available from: Peace Corps Information Collection and Exchange 806 Connecticut Avenue, NW Washington, DC 20525 USA Reproduction of this microfiche document in any form is subject to the same restrictions as those of the original document. APPROPRIATE TECHNObOGlES FORDEVELOPMENT of l-Slow Builtlimgs S INFORMATION COLLECTION & EXCHANGE MANUAL NO. M-6 INFORMATION COLLECTION AND EXCHANGE Information Collection and Exchange (ICE) was Peace Corps' established so that the strategies and technologies developed by Peace Corps Volunteers in their field work could be made available to the wide range of development workers who might find them useful. Training guides, curricula, lesson plans, manuals and other Peace Corps-generated materials developed in the field are collected and reviewed: some of these materials are reprinted; others provide an important source of field-based information for the production of manuals or for research in particular program areas. Materials that you submit to the Information Collection and Exchange thus become part of the Peace Corps' larger contribution to 'development. A listing cations is of all Information available through: Collection and Exchange publi- Peace Corps Information Collection and Exchange OZfice of Programming and Training Coordination 806 Connecticut Ave., N.W. Washington, D.C. 20525 ICE Reprints, Manuals, and Resource Packets are available on request to Peace Corps Volunteers and staff. On a limited most are also available to field workers in developing basis, nations. Others who may be interested in obtaining these materials may purchase them through National Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 22161, and a few selections are available through Volunteers in Technical Assistance (VITA), 3706 Rhode Island Avenue, Mt. Rainier, Maryland 20822. Add your experience to the ICE Resource Center: send materials that you've prepared so that we can share them with others working in the development field. Your technical insights serve as the basis for the generation of ICE manuals, reprints and resource packets, and also ensure that ICE is providing the most updated, innovative problem-solving techniques and information available. SELF-HELP CONSTRUCTION OF l-STORY Written Peter BUILDINGS by Gallant illustrated Nancy edited by Bergau by Jim Seaton Peter Hunt Information Peace Corps Collection and Exchange Manual M 6 Special Printing for AID Resources December, 1980 Self-Help Cons&.&ion of I-Story Buildings is the sixth in a series of publications being prepared by the United States Peace Corps. These publications combine the practical field experience and technical expertise of Peace Corps volunteers in areas in which development workers have special difficulties finding useful resource materials. PEACE CORPS Since 1961 Peace Corps Volunteers have worked at the grass roots level in countries around the world in program areas such as Before beginning public health, and education. agriculture, Volunteers are given training in their two-year assignments, This training cross-cultural, technical, and language skills. helps them to live and work closely with the people of their development It helps them, too, to approach host countries. problems with new ideas that make use of locally available resources and are appropriate to the local cultures. Recently Peace Corps established an Information Collection & Exchange so that these ideas developed during service in the field could be made available to the wide range of development Materials from the field workers who might find them useful. are now being collected, reviewed, and classified in the The most useful Information Collection & Exchange system. The Information Collection & Exchange materials will be shared. provides an important source of field-based research materials for the production of how-to manuals such as SeZf-Help Constmction of I-Story Buildings. THE AUTHORS Pete Gallant served as a Peace Corps Volunteer in Liberia for three years. During that time he worked on and supervised a variety of projects involving the construction of l-story schools, roads, Mr, GaLlant-holds a Bachelor and bridges in rural areas. of Arts degree in Political Science from St. Joseph College; he is now working with the U.S. Department of State. (iii) Peter Hunt workes for several years in the audio-visual and training departments of Save the Children Federation where he worked on materials to help field workers promote cornmunityHe is now a free-lance video directed construction projects. and print-based training materials producer and develops videofor national and international organizations. Seaton is Co-Director of Communications Development Service organization that provides field training (CDS), an independent He specializes in designing materials for development workers. and informal educationalexperi.?nces that help community members focus on their own knowledge, experience, and human resources -Mr. Seaton is currently as the basis for self-development. developing training workshops in nutrition planning for several countries to help government staff respond effectively to community initiatives in integrated rural development. Jim the graphic artist for this manual, served with the Nancy Bergau, Peace Corps as a graphic design consultant to the National Broadcast Training Centre and TV Pendidikan (Educational TV), both Before joining Communications Development Service in Malaysia. she also worked as art director for a to work on this manual, multi-media public health education program. Ms. Bergau has extensive professional experience with the full range of graphics Her illustrations proved invaluable and audio-visual production. in shaping the manual's text and in making the more complex technical details easier to explain. Many thanks preparation are due here to a number of this manual: Santa Cruz Henry Baker, Director, Recreation, Santa Cruz, California. of people City who aided Department of Parks Program Director, Rice Steve Bender, Consultant. Center for Community Design and Research, Houston, Tom Callaway, Director, Office of International Development, Washington, Division Affairs, D.C. Earl Kessler, Self-Help Cooperative Housing. Construction Special are due to: notes of thanks of Technology Department of Advisor, the University Texas. and Documentation, Housing and Urban Foundation for Brenda Gates, for her continued support as Project Director the Peace Corps Program and Training Journal Manual Series. Karen Seaton, Communications work andproduction assistance Development with this (iv) and Service, manual. for her of lay-out Please a reply form has been provided here. For your convenience, send it in and let us know how this manual has helped or can be If the reply form is missing from your copy made more helpful. of the manual, just put your comments, suggestions, descriptions on a piece of paper and send them to: of problems, etc., SELF-HELP CONSTRUCTION Peace Corps Information Collection & Exchange 806 Connecticut Avenue, N.W. Washington, D.C. 20525 U.S.A. w PLEASE RETURN THIS FORM because Peace Corps NOTE TO USER: This manual was published workers and volunteers wish to help in a growing area of worldwide In order to provide the most effective help, the interest. preparers of the manual need to know how it is being used, or how Please fill in the you feel it could better serve your needs. followinq form and return it to: SELF-HELP CONSTRUCTION Peace Corps Information Collection & Exchange 806 Connecticut Avenue, N.W. Washington, D.C. 20525 U.S.A. WHEN WE RECEIVE THIS FORM, WE WILL AUTOMATICALLY PLACE YOUR NAME ON A MAILING LIST SO THAT YOU WILL RECEIVE: . Updates and/or additions become available. . Notice of other and corrections publications w'nich to may be of the manual interest as they to you. If you have questions on the material presented in the manual, or if you run into problems implementing the suggestions offered here, Use additional paper if you please note them in the space provided. have to in order to be as specific as you can about the problem. we will try to provide, or direct you to, an Wherever possible, answer. * * * Date Your Company or Agency, if any Your Name Your 1. Address How did you find 0u.t about of I-Story BuiZdings manual? the Peace Corps SeZf-HeZp Construction How did you get your copy? (vii) manual have Which parts of the useful? Why? 3. Did you find the manual complete or incomplete? 4. How has this manual helped apply the information? 5. Can you recommend additional methods or equipment which you If feel'should be included in a new edition of the manual? please include the information you know of such methods, etc., here. 6. What were your successes using the manual or implementing Please describe of the ideas or procedures? Problems? completely. 7. Do you have other easy you found to read, your work? most too useful? Least 2. simple or complex, What have you done to any recommendations? Privacy Act Notice: Furnishing the information requested herein is completely voluntary. It is requested under authorities contained in the Peace Corps Act (22USC 2501 et seq.). The only uses which will be made of this information are as follows: 1) For management purposes involving the format of future issues of this publication; 2) For incorporation in a mailing list for this and other similar publications. TABLE OF CONYENTS Page About This . . . . . . . . . . . . . . . . . . . . . . . ..“................. Manual ReplyForm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~~...........~..vii . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . ..1 INTRODUCTION A Note on the Development Projects....................... How To Use This What This 1 BASIC Site iii and Construction . . . . . . . . . . . .. . . .. . . . . . . . . .3 Manual................................,....5 Manual PLANNING and Process Will AND Talk About . . . . . . . . . . . . . . . . . . . ...*.*.. DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . -11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Position ', How Big Should the Site Be?..........................1 and How Private Should the Site Be?..1 How Accessible, What Kind of Soil Should the Site Be On?.............1 How Well is the Site Drained?........................1 How Should the Building Be Placed on Its Site?.......2 Summary of Factors Affecting Site Selection..........2 Size, Shape, '\ and Floor Plan Materials Rammed Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...*.* (Mud, Pise) (ix) 4 6 8 9 0 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 "..School s .............................................. Clinics .............................................. Homes ................................................ What Size Will Each Room Be?......................3 Using Measuring Units to Help the Family Plan Its Own Floor Plan ............................... Helping the Family Draw Its Own Floor Plan........4 Drawing the Floor Plan of A House.................4 In All Buildings........4 Doors, Windows, and Ceilings Where Will Inside Doors Be Placed?................4 How High Will the Ceiling Be?.....................5 Where Will Windows and Outside Doors Be Placed? How Will They Be Designed, and What Size Will They Be?. ........................................ Windows in a Tropical Climate.....................5 Protecting the Inside of the Building From Rain and Insects ...................................... Taking Advantage of Any Breeze....................5 Windows in A Desert-Like Climate..................6 Exterior Doors .................................... Construction 6 and Adobe Bricks............67 22 25 27 0 31 1 2 8 8 1 52 3 56 8 2 65 66 Page Wood .................................................. Bamboo ................................................ Stone/Rock ............................................ Cement and Materials Made With Cement.................7 Mortars...............................................~ ............................................... Concrete Reinforced Concrete...................................7 Blocks ................................................ Concrete Blocks.......................................7 Sand-Cement Blocks (Sandcrete)........................ Stabilized Earth Blocks...............................7 Summary ............................................... 2 DETAiLED PLANNING Planning FOR Foundations CONSTRUCTION.. Planning Walls, 83 84 For and Roofs Doors ...................... DIRECTIONS Setting FOR CONSTRUCTION Out iLaying Out). Marking Batter ......................... ................................ .......................................... the Foundation Outline.......................12 Boards ........................................ Orientation (x) 92 93 94 5 96 101 .......................................... Roof Styles and Their Functions......................l-............................... Roof Materials .. ...... Construction Details For Roofs.......................10 3 8 90 ...................................... Windows, 88 0 Wall Height and Length ................................ Wall Thickness ........................................ Placement of Doors and Windows........................9 Construction Details for Doors, Windows and Interior Walls ................................................ Planning ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 2 PlanningFOoors...........................................9 of Floors. 2 74 5 5 6 76 . . . . . . . . . . . . . . -79 Footings .............................................. Foundation Walls ...................................... Deciding Upon the Materials and Dimensions .......................................... Foundations Drawing Final Foundation Plans........................8 Types 69 69 70 0 t 7 115 ,116 119 0 123 4 Page Construction of Foundation . . . . . . . . . . . . . . . . . . . . 127 Footings Digging the Foundation Trench........................12 Formwork For Footings................................12 Making the Concrete For Foundation Footings ......... Pouring the Concrete For Foundation Footings.........13 Curing the Concrete For Foundation Footings..........13 Reinforced Footings..................................13 Construction of Foundation Walls of Floors of Walk, of Roofs 8 140 0 0 1 5 148 1 1 153 154 Windows, and Doors ............. Block and Brick Walls ................................ Making the Blocks or Bricks.......................15 Blocks With Cement Content.....................15 Adobe Bricks...................................15 Laying Blocks and Bricks .......................... Framing Windows and Doors.........................16 Roof Preparation..................................16 Rammed Earth Walls...................................16 Earth Mixture ..................................... Forms ............................................. Procedure.........................................l7 Framing Windows and Doors.........................17 Roof Preparation. ................................. Construction 5 6 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 Earth Floors ......................................... Concrete Floors ...................................... Construction .I30 . . . . . . . . . . . . . . . . . . . . . . . ,138 Concrete Foundation Walls............................13 Block Foundation Walls ............................... Making Blocks.....................................14 Making Concrete Blocks.........................14 Making Sand-Cement Blocks......................14 Kaking Stabilized Earth Blocks.................14 Laying Blocks ..................................... Finishing the Mortar..............................15 Rock Foundation Walls................................15 Construction 7 9 ,157 157 7 7 7 160 4 6 9 169 170 0 1 172 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Flat Roofs ........................................... Shed Roofs ........................................... Gable Roofs..........................................l7 (xi) 172 173 6 Page 4 CONSTRUCTION WITH 181 .......................... BAMBOO 183 .................................... Bamboo For Foundations Bamboo For Frames. ........................................ 183 Bamboo For Floors. ........................................ 185 186 Bamboo For Walls .......................................... Bamboa For Roofs..........................................18 Bamboo Reinforcement Preservation 5 Pit. of Concrete..........................18 8 ... """18 8 ..18 9 ............................................... of Latrines 190 ...................................... ... ................................................ """19 1 Base ...................................................... 192 Floor ..................................................... 192 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 Shelter.... 6 7 of Bamboo. ............................. LATRINES Location 187 and Windows .............................. Bamboo For Doors CONSTRUCTION llh EARTHQUAKE Selection and Preparation Selection of Reinforcement APPENDICES Building of the Materials of Buildings 195 ................. AREAS 196 Site ..................... 198 ........................... 198 ................................ 201 . . . . . . . . . . . . . . . . ..“....““.“.““.“.““......“..“.... Calculations Support 2. Step-By-Step to Check Whether a Building............ Directions 3. Estimating the Amount 4. Estimating Materials Site will a Proposed . . . . . . . . . . . . . . . . . . . . . . . 202 For Drawing of Concrete Needed (xii) Foundation Needed To Build Plans...218 For a Floor...215 Walls.............217 Page r; Reference _. 6. Metric U.S. 7. Sources 8. Tables Measurements Concrete Used in Construction.....,........221 This Manual and Their Equivalents.........................,............225 of Further "Human Measuring Floor for Information..........................226 Pieces" For Designing Plan............................................231 (xiii) Room Size and INTRODUCTION This manual has been designed to help field workers with little or no construction experience assist a community or family to *plan and ,&sign a l-story community building (such as a school or health clinic) or home that fits their present and future needs, *assess the advantages construction advantages of locally materials, -draw and understand construction plans: .successfully according to or disavailable their and own complete construction their own plans. FLOOR PLAN: VIEW OF A BUILDING ABOVE FROM SIDE VIEW OF THE SAME BUILDING The aim 1) is to present construction process in three basic steps: exploring the needs of the people who will use a first, that will fill as building and arriving at a basic design the basic design includes many of those needs as possible; decisions about the number and size of rooms, the arrangethe major construction materials that ment of the rooms, and the choice of a site for the building; will be usedl 2) second, for each roof; 3) the third, written construction from the foundation working out a detailed, part of the structure, actually constructing the building according plan to the to plan. the manual focuses on basic principles In its technical sections, of construction with materials that are low-cost, available in many In any given locale or and easy to work with. parts of the world, different materials (or combinations of materials) will be climate, But understanding the construction available--or suitable. principles covered here should help the field worker work with self-help groups to adapt the specific step-by-step suggestions to whatever materials are available to them. No book could hope to cover all design and construction problems This manual presents some of the most widely used or situations. But in many cases, field innovations in local materials and design. workers and communities will need to adapt these ideas tc conditions The Peace Corps Information Collection & at the project site. Exchange hopes to incorporate such local adaptations in future Any comments, suggestions, or new ideas supplements to this manual,. are most welcome. Please send information about your construction project's experience to the address on page (v). One final note: the essentials of the construction process are well But the within the understanding and skills of community groups. field worker should always have one or more advisers in mind who In any can be contacted if problems arise during construction. projec-t, no matter how simple, unforeseen difficulties or special conditions may pose problems that this manual does not cover. We especially during the planning have tried to indicate those areas, of a construction project, in which assistance from someone experienced in local construction problems may be needed. In addition, the bibliography at the end of the manual lists other valuable sources of more detailed information in Appendix 7. A NOTE ON THE DEVELOPMENT PROCESS AND CONSTRUCTION Few things can inspire a community or family more than seeing and using a building that they have built together. In fact, getting a community to cooperate on a simple construction project is one of the best ways to help them start tackling their difficult development problems. But not all construction projects are effective. In thousands of communities all over the world, schoolsl clinics, and homes have been built for people and thenlzever used, because the design of the building was unacceptable to the people, because the community could not afford to operate it and felt no sense of ownership,. or because the building didn't fit the community's priorities. When thinking about a construction project, therefore, the field he/she hopes worker should remember that the imediake improvements will result from a new building are less important than the community's participation in planning, budgeting, constructing, and then using a new building itself. The experience of working together on a project can lead to increased interest and confidence in further community-managed development efforts. But simply watching while a building is planned and built by others can seriously hurt community confidence and provoke hostility to development efforts. The community or family must be (and must recognize themselves key actors in all stages of a construction project. But the worker still has a crucial role to play in the process. The worker can function: 1) as an initiator of the project,a non-formal educator, and a catalyst for decision-makinq. Where traditional approaches or solutions are not serving community members well enough, the field worker can help them explore and define their own needs/solutions from a new problem-solving view-point. There are organizations in almost all countries that provide information and training in techniques that promote this exploration process. 247-811, 0 - 77 - 2 as) field field the 4 2) Once a community has decided to build as a planning assistant. the field worker can provide valuable a home, school, or &lxic, information and assistance to help them design the building, and organize the construction purchase and assemble materials, to provide basic technical This manual is designed process. information the field worker needs to help a community. Community groups have limited access fund-raiser. 3) as a project The field worker to the funds needed for small local projects. generally has much greater knowledge of, and contact with, and international agencies that could government, private, The Information Collection and support a community project. Exchange publishes a manual, Recources for Development Agents, that may be useful for field workers trying to get technical or The manual talks about analyzing resource financial help. needs and gives names and addresses of organizations that For a copy, write to: provide those resources. Peace Corps Information Collection & Exchange 806 Connecticut Avenue, N. W. D. C, 20525 Washington, U. S. A. Peace Corps Partnership Program can be a source of In addition, funds to support small community construction projects. Grants of $1,000 to $5,000 are made to communities that have initiated plan to use volunteer labor, and donate their own project, For information'*and application forms, 25% of all materials. Peace Corps Partnership Program, at the write to Director, address above. SUCCESS OR FAILURE? Once the decision to concern should be to succeed. Success depends build has been made, the field workerls ensure that the community's self-help on several main efforts factors: * Those who will ultimately use the building should be actively involved inevery stage of the project---from conception to planning to construction: their needs, desires, and budgetary restraints should be decisive in all planning issues; and the The project must depend on their desire to pursue it. field worker should never be the actual leader of the He/she should provide assistance, not direction. project. * The building plans should be simple, and affordable. far as possible, the construction materials should available. As be locally * The completed building must be useful: it should have adequate space for its intended use and it must be comfortable, Space for future additions or healthful, and attractive. needs should be planned for. 5 How to Use This Manual DISCUSSION this manual presents information that For the most part, anyone planning a simple construction project needs to have. By reading each section thoroughly in sequence, field workers can prepare themselves to assist community groups that n.=ed technical assistance. The sections can also be referred to individually at any time specific information is needed during construction. ILLUSTRATIONS There are illustrations the process easier to using these illustrations these groups understand PLANNING throughout the book designed to make visualize. Field workers will find that with the community/family will help the field workers' suggestions. EXERCISES In Section 3: Basic Planning and Design, there are suggested exercises with paper cut-outs that a family or community group can work on together i.. order to design the size of each room they need, and the floor-plan (the arrangement of the rooms) of the building. These are most effective when the field worker is present to help the group explore their needs thoroughly and to help them prepare the cut-outs. What Basic This Manual Planning Will and * will be built fill chance of designed with more * is designed abandoning space will the present of success, any construction proto ensure that the completed the budget the present and resources needs of available; those who will use and placed with future needs in mind without the original structure (for example, if more be needed two years from now, can it be added site?). CAN THE PROJECT BE BUILT Five things construction About Design To have a reasonable ject must be carefully building: * can Talk it; on WITH THE BUDGET AND RESOURCES AVAILABLE? affect a self-help project: availability 0 money l time l labor (for l organization l gro_upls of ability construction construction to complete a materials and maintenance) Availability of Construction Materials. There are many different construction materials available. Denending on local conditions such as climate and supply, each one is-suitable for different of a building. Each has advantages and disadvantages in terms suitability, cost, time, labor, and durability. A family or community should understand the basic characteristics of all available materials in order to make the best possible choices fill their needs. parts of to Money is needed in construction projects to buy and transport any materials that are not available near the construction site. costs can be significantly reduced by using locally available materials. In most areas, almost the entire building can be built from these supplies. However, care must be taken to choose materials that are durable and safe. Materials fcr some parts of the building, especially the foundation, may be worth purchasing, even if financing is difficult. Time. Different construction time to prepare and assemble. seasons. Thus the choice of schedule of work, all depend construction. materials Some can materials, on how much require different amounts only be used in certain building design, and time is available for of 7 Different materials require very different amounts 'and kinds Labor. certain roof designs Some parts of a structure-especially of work. --require many more people than others, or people with different who can work on a project, their skills. So, the number of people level of skill, and the time they can devote to the project must be considered while planning construction. t building has many different parts, %%%%%iat~~~~ %o~~~~$~s, doors, windows, and roof. These must often be built in a certain order (for example, the walls usually can't be built before the foundation). In addition, each part may be made from several materials that must be put together carefully and in a precise order. For work to go smoothly, the builders must be able to organize the project: to estimate in advance what materials will be needed, how much of each will be needed, and to bring the correct supplies to the site at the right time. Many projects fail because a vital material is not ordered in time and all work must stop until it arrives--sometimes too long a wait for work to begin again. WILL THE BUILDING USE IT? FILL MORE OF THE PRESENT NEEDS OF THOSE WHO WILL All build2ngs should be durable, addition, other considerations or family designing a building. healthful, and comfortable. In should be kept in mind by a community A community planning a clinic or school must consider many different needs. For example, a clinic would have to have space for treating patients, for people to wait before they are treated, and perhaps space for one or more people to stay overnight while recuperating. These would be the primary needs. However, the community might also desire to use the clinic for educational purposes: health education, for example, or nutrition classes. The most effective design would depend on aZZthe planned uses of the building. The A family needs to plan enough space for all family members. family must decide how many rooms they need, what kinds (dining, sleeping, Other needs may include ease of etc,) and what size. movement, storage space, privacy, etc. IS THE BUILDING Present needs DESIGNED WITH FUTURE NEEDS IN MIND? may change soon: l there may be many more years fromnow; or the meetings in the school l a doctor may move into living space near the the community clinic; l a family need may grow and students in the school 3 community may start holding next year; more room. and need 8 Future needs like these can be difficult to fill if the building is constructed next to something (like a river or road) that will block or if it is designed in a way that makes future construction; The easiest way to ensure that a building will additions impossible. be useful throughout its lifetime is to anticipate future needs and plan so that they can be filled easily by adding to the present design whenever they arise. SITE In SELECTION addition which direction Four factors position: AND POSITION to a building's design, it faces (the.position) must be considered in where it's located are crucial to choosing the best Will a school, ,for example, *location: all students to reach? Can construction to the site easily? *terrain: drained affect Is the land hilly or subject-to or marshy? building design, safety, *Size of Is there Nanning Buildings l footing have and 4 basic Directions parts: and foundation 0 floor l walls, l roof doors, and windows and easy for be brought or soft? wellAll these factors land for the building? to the building? prevailing *Climate: The temperature, affect the comfort and healthfulness posit&n of a building is crucial in environment inside the building. Detailed be relatively materials flat? hard earthquake? and comfort: Is there enough future additions the plot: room for (the site) its success. site and winds, and rainfall all And the of a building. helping to control the Qor Construction the information needed to draw Section 2 of the manual contains plans for each of these parts. Section 3 contains step-by-step guides for the actual construction: that is, how to work from written plans to complete a structure that will last a long time and require a minimum of maintenance. FOUNDATIONS The foundation of a building provides a level base for the structure to stand on. It must be strong enough for the building that sits on it; it must be level and plumb (straight up and down); and it must be secure from damage by water, frost, settling earth, and earthquakes. FLOORS Floors provide a secure, level, and comfortable surface for everything inside a building. They must be far enough above ,ground level to remain dry, easy to keep clean, non-slippery, and level (so that objects do not roll or slide). WALLS, DOORS, AND WINDOWS Walls provide privacy and shelter from the elements. They also hold up the roof. They must be thick enough to protect the inside from heat or cold, strong enough to support the roof and withstand wind pressure, and high enough so that people can stand comfortably without hitting their heads on the ceiling. Doors and windows provide light and ventilation. In addition, doors (or doorways) allow people to move in and out of the building and between rooms. They must be designed to allow only as much light, air, cold, and heat as desired into the building; at the same time, they must keep insects, dirt, and rain outside and provide privacy when closed. ROOF The roof protects a building from rain, snow, wind, cold or heat, and insects. It must be designed to withstand wind pressure, and the weight of anything that might fall on it. In addition, care must be taken to ensure that community members will be able to build the roof (the parts cannot be too heavy to lift). Latrines Latrines are important to good heal,th because they can eliminate diseases spread through human excrement. They should be included in the planning of any public building or home. Special rules apply to their location, positian, and See Section 5, construction. page 189. Earthquakes Earthquakes place severe stresses on' buildings. But there are many methods of construction, principles of design, and materials that can help a building withstand tremors--at least long enough to allow occupants to escape safely. Most of these earthquakeresistant techniques cost nothing at all, or are very inexpensive. Builders in earthquake zones can and should use these techniques even when their budget is limited. See Section 6, page 195. BASIC WANNING AND DESIGN Before construction can begin-or detailed need to consider can be drawn-- the builders and design questions: SITE will the SHAPE, will will the l What l How will each room in relation to the (that is, what will plan be)? the each family room be? be placed others the floor What shape will the building be? Round? Rectangular? Some other shape? . How high l be AND FLOOR PLANS 0 HOW many rooms will or comraunity need? size building on? o Where on this site building be placed? ' for construction basic planning AND POSITION o What land constructed SIZE, plans three Where be? will will the doors ceiling be? and windows -1. I.. *: “ 2; : 13 CONSTRUCTION MATERIALS . What floor will the foundation be made of? and e What will and doors the walls, windows, be made of? o What of? the will roof be made There are a number of simple guidelines that anyone planning a But it is building can follow in answering these questions. important to treat them as guidelines and not as hard and fast Those who will use There are rarely any "right" answers. rules. the building must be prepared to find compromises between their needs and budget on the one hand, and the limitations of local and construction materials on the other. climate, soil, geology, This section of the manual is designed to help the field worker and community member(s) work together step-by-step to answer the three basic planning questions above for schools, health clinics, and homes. By following the process sugg?si:ed, the builder will end up with an accurate picture of what his or her building will be like. 14 SITE AND POSITION Families and communities need to decide carefully where they will build. They need to know their building's: .SITZ The plot of land the building will be on; where will the land be? what will its boundaries be? how big will it be? ,POSITION The exact position of the building on the site; which way will the building face? how far will it be from each of the site's boundaries? .-.-18.11 I i Taken together, site and position are just as important as, if not more important than, how well the building is constructed. They can determine a building's safety, usefulness, and durability. In addition, a well-chosen site can significantly cut the cost of construction and maintenance. How Sig ShouId the Sii i POSSIBL;v I r---7 HOUS: SITE i i i h ---II !!” 1 i* dB - Be? At the very least, the site must be big enough for the building being planned plus at least some room around the building for the storage of construction materials during the construction. Generally, about 2 meters along each side of the building is the minimum builders will need. In urban areas, extra land may be required for health, safety, transportation, or other needs. A major note of caution here: a site can only be truly adequate if it leaves enough room for present and future needs beyond the space taken by the main building being planned. These needs will be different for different types of buildings. y-.rr.rr.-.-, ! LATRINE I iFKiz~ i i I i . STREAM -- i I GARDEN - I i i i i i Ci I- 15 Here are some of the things planners might want to leave space for: Schools - a shaded outside area for assemblies, lunches, outdoor classes - recreation area for sports, play - future classrooms - other additions such as offices, library, theatre, school garden - compost pile - livestock/poultry pens at least - two or more latrines 17 meters from water supply - cistern/well - lodging for teachers - storage for school and maintenance supplies Health .~.~.I.-.-.B.~.-.~.I. I ’ I GARDEN I . I --- I I FUTUIRE-EXPAN~ I ON r I I I. I I. UTURE MEETING ARE.A ’ I I I DMS ! . : L ---0 I LATRINESM 0 i I* I. I i i .a.-.lr~I.-.II.I.-.-.-. i LATRINES . I, r--F;-&---l !i RECUPERATION 1 --Y-III-- I H0m.es - outdoor latrine garden livestock/poultry additions future well Y-I-----pens to the ; I i. Clinics - future additions for extra reception and treatment rooms - cooking area for patients who must stay in clinic - latrines - well - lodging for health workers/ doctors - separate building for maternity care and recuperation i SMALL -CLIN I C home Many of these needs may appear farfetched to the family or community plan their building when they first However, the field worker project. should urge them to allow room for as much future. expansion as It is always easier to add to a present building and possible. site than to start over again because there is no room at the first site. 16 Even in cases where gi3x al1 cr,.ough site * to their site might In addition to consider other expansions: . rivers, . heavy the actual conditions size of the at the site site, that afford a large what land next planners need to might block future streams forest . unsuitable marsh) . the family or community cannot fiitilre needs, theycm consider be obtained for later expansion. or land roads, markets, buildings bush (such as existing Whether these obstacles are on the projected site itself, the land next to it, care should be taken that they will block the builders' present or future needs. HowAccess ible, and How Private Should the Sit& or not on Be? A building can only be easy to build and easy to use if the site if it is conveniently close to other people is accessible; that is, and places in the community and if it can be approached easily. At the same time, a building use it if the site provides Privacy can also be important and smells can cause serious to a heavily travelled road. Because the for privacy, can only be comfortable for those who enough privacy to satisfy their needs. for health: for example, dirt, dust, problems if a building is too close need foraacessibility planners often have often conflicts with the need to compromise between them. 17 Unless the materials for Access for Construction. construction are available on the site itself, some or all of them will have to be brought to the site in large amounts. Generally, this means the site should be near a road, or in an area where a road to the site can be built. -In addition, there must be space on the site to store materials during construction. To serve its purpose well a building must Access for Use. For different be easy for people and supplies to get to. kinds of buildings different considerations should be kept in mind. For example: SchooZs should be - within reasorlable travel distance (by foot and/ or vehicle); - close to clean water; - close to fuel supplies in cold climates; CZinics should be - centrally located so that them easily; - close to clean water and - next to a roadway suitable the community can reach fuel supplies; for vehicles; Homes should be close to clean water for cooking close to neighbors; close to fuel supplies; close to the family's fields or the family earns income; - close to markets; - close to community facilities. - Privacy, should and washing; other places where All building sites Health, and Safety. Comfort, be: - away from rivers and streams heavily infested with or other sources of disease; mosquitoes, bush, or jungle (all these cut off - away from forest, breezes, are dangerous in case of fire, and provide homes for snakes, rats, ants, and other pests): - away from major roads and other sources of noise, smells (this is especially dust, dirt, distraction, important for schools and clinics); - away from flood-prone areas; - away from fault lines in earthquake areas (see section on earthquake areas, page 195. 18 What Kind of Soil Should the Site Be On? Possibly the most important consideration in choosing any site is that the soil must be able to support any building(s) erected can be built on (or over), but the nature Almost any ground on it. of the site chosen will affect the simplicity or complexity of the cost of construction in labor and money, and the foundation, the durability of the building. . Rocky soiZprovides the strongest s-upport for a building, usually much more than is necessary for a l-story building. But while it is extremely stable, it can be very hard to excavate. l Hard-packed cZayis strong, l a but easy generally to work the with. best soil for l-story buildings: Sand a=pdgravezare usually acceptable soils for l-story They can support about half as much weight construction. as clay, but they are subject to shifting or slipping, especially if the site is-not on level ground. Soft b2ack sod2, drained ma.rshZand, and %ade" earth CfZ22 thut has been co22ected and packed) are satisfactory soils for construction. buildings constructed on these soils should be However, built on concrete foundations, or on raised platforms. In addition, buildings on these soft soils should be made -..v --a. a.ULJ available. with the lightest suitable rn;rfar;-lBlack topsoil contains decayed organic matter that makes In areas where such soil it soft, especially when moist. goes more than 30-45 ems. deep, it must be removed before Otherwise it will almost certainly construction can begin. cracks or collapse shift under the foundation and lead to wall of the building. Each type of soil has very definite limits to the weight it will l-story buildings will be well support. Generally speaking, within those limits except in the case of buildings with rock walls on the weaker soils. When a tentative site has been selected, double check that the soil at .2he site building safely. Quite often this can at similar nearby buildings (2 or more years old) on the If they same kind of soil. show signs of uneven settling such as cracks in the walls or foundations, the side of the new building may have to be dug out and filled with firmer soil, or another site may have to be selected. it's a good idea to will support the planned be done simply by looking 19 In cases where there are no similar buildings nearby, or no an estimate of the planned building's weight similar soils, per square meter should be made and compared with the weightDetailed directions for calculating bearing capacity of the site. plus a guide to the weight-bearing the weight of a building, capacity of various soils will be found in Appendix 1. Almost as important as the type of soil at the site is the If the ground at the site contains a of the soil. mixture of different soils,it must be dug out and filled in until it is uniform in order to provide a stable support for any building. uniformity If the ground at the site cannot be made uniform, or if the weight of the planned building will be close to the weight-bearing it may be necessary to use reinforced capacity of the site, concrete in the foundation. How We13 is the Site Drained? In addition to the weight the site can support, builders need Water seepage can to consider how well the land is drained. destroy even the strongest foundation if it is not controlled or planned for. Wet or damp floors can make a building uncomfortable and unhealthful. Whenever possible, mmshZand or any ground that lies underwater for extended periods of time should be avoided for construction In some areas, people have developed methods for conpurposes. struction on stilts because they have no access to dry land, or because they depend on access to the water for economic support. Buildings in these areas should be made of light materials and should be replaced often. LOU-lying 2and, and land that may be exposed to short-term flooding is also less than desirable for construction purposes. When there is no choice, however, this kind of land can sometimes be improved by digging a trench about 25 ems. wide and lo-15 ems. deep around those sides of the building site that won't drain. These trenches should lead far enough from the planned position of the building to keep water from rising to the foundation depth. 247-801 0 - 17 - 3 20 is more than 30-45 ems. If the dark topsoil in low-lying areas effort to find a different site should IX made, since deep I every removing this topsoil for a firm foundation will be expensive and can make effective drainage much more difficult. High, dry groundis usually the best for building sites since However, not subject to the ill-effects of water seepage. Planners need to avoid or guard against can be too high. dangers: *if the ground is a level area for expensive; the excavation also hilly, the foundation may be too needed difficult it is ground these to produce or rapid drainage may cause *if there are heavy rainfalls, or landslides that can cause a ground slippage, erosion, building to collapse or can bury it; in most cases, a retaining wall and carefully planted trees can solve these problems, but both alternatives can be expensive; *if high building roof. The ideal site ,and sheltered ground is exposed may be in danger to of high winds or storms, the collapse, olr it may lose its for any building is on dry soil against gro*und slippage, strong safe winds, from and flooding storms, 4 How Should the After selecting site the building is chosen should Building Be placed On Its Site? the builder needs to decide where on the a site, The position that or buildings planned will be. ideally: l be far enough back from the site boundaries for privacy and comfort cleave room for future additions *leave sufficient room for storage of construction materials l allow the windows and outside doors to face as close to north and south as prevailing winds will allow (see the section on windows and doors, page 52) *be as level as possible ebe as dry and strong as possible brush, or jungle area on the site abe away from forest, @conform to all local legal regulations. 21 Summary of Factors Affecting The most consider important factors in choosing a site gwhether the the building; *whether prevent soil Site Selection community for their will groups building support the site is drained water damage: @whether the site their immediate is large and future and families are: the weight to @whether the construction site is easily accessible and use of the building: @whether healthful. site the is of well-enough enough needs; comfortable, safe, should to accommodate for and In most cases, builders have to compromise between these concerns. Choosing the best site among several less-than-ideal possibilities It is always best to get is often difficult and complex. Contractors, whenever there is any doubt. experienced advice, or architects in the area can help make the options engineers, clear, especially in terms of cost and labor. 4 P O?W F&zZ Gaxtim. In many areas, local regulations will influence what can be built;-where it can be built, and how it can be built. Building and zoning codes, permits, licenses, and accepted practices vary widely from country to country and locality to locality. To avoid wasted or illegal effort, the field worker should help family or community members learn their restrictions and obligations during the basic planning and design process. on a This should always be done before settling definite site for construction. 222 SIZE, SHAPE, AND FLOOR PLAN sohools the smaller a building, the less it will cost to build. Generally, So the first aim of any community group planning a new building If they should be to decide what their mintium space needs are. it will be easy to add room can afford more than the minimum, before construction plans are final. Small community schools are generally simple to plan a minimum of 1.3 square meters classrooms, For example, in a l-room school for 30 students (the most that should be planned for in one class), you would need about 30 x 1.3 For design. per student. indoor ACHER EE (sl = 39 square meters for seating. Add to this about 2 meters in front for a chalkboard and teacher's desk/table. This like: is what it could look Classrooms for fewer students can be smaller as long as there is about 1,s S~EYW meters per student for seating and about 2 meters across the front for the teacher. if the community However, can afford it, it is a good idea to build every classroom at least 5 x 8 meters. The extra space will come in handy for exhibits, special projects, and extra students if class size increases. I 23 B It end more storage and/or of the school. 6 1 I--I I I i office space STORAGE I is required, add it on the OFFICE PORCH i I I L-- If there will be more than 1 teacher, the plans should include one room for each teacher and his/ The additional her students. classrooms can be added as needed next to the first. If the community plans to use the school as a public meeting room, thought should be given to making the first classroom larger than needed to accommodate large adult assembly room groups. Or, a large might be built specially for the purpose and attached to the class for use as a theatre. Many communities, especially tropics will want to plan porch for use in very hot in the a shaded weather. r-----7--y--7 I I I, I FUTURE CLASSROOM ; 1 --em r --- -1 ---- I---- J FUTURE LIBRARY,EXHIB/TS I I IL------ i 24 Don't school apply forget to plan for latrines and a water supply for special grounds (see section on latrines to the location and number of latrines). If needed or desired, thought lodging for a school garden, Here is one possible site should teachers, plan be given to and sports. including these t i. Ii TEACHERS ’ BEDROOMS h s s u VI .n I ! 1 I I. (I ! I FUTURE ADDI’ TIDN i 5 i E L -- C i A WELL r RECREATION space features: LATRINES --- on the rules that -B-w-- i I i I eT”a i i i i COMiOST I. -e 1 GARDEN ! I I---; L I V’ESTOCK i ! ! i for 25 Health Clinks planning than schools Health clinics usually require more advance because separate rooms are to fill a community's needs well, needed for the reception and treatment of patients, care of patients who must sleep in the clinic, and space for office and In addition, latrines should be included in the plans supplies. for any clinic (see separate section on latrines for detailed planning). LATRINE 4 m. 3 m. This is a floor plan for a health station, with 3 rooms and 2 inside walls, measuring 7 X 5 meters. small Ii *m OFFICE/ SUPPLIES RECEPTION/ TREATMENT , I PAT I ENT BEDRSUM A more complete clinic might be twice the size, 7 X 10 meters. To reduce noise that may disturb in-patients, and to reduce the patient rooms should be as far as possibility of infection, possible from treatment rooms. 3Ii I i m I RECEPTION PATIENT BEDROOM: TREATMENT OFF I CE/SUPPL’I ES. LATRINE 26 LATR I kr A desirable addition to one of these clinics would be a midwife station in a separate structure on the same site. Midwife stations permit special care for mothers and babies during and after delivery, without exposing them to infection from clinic patients. Here is midwife a possible station. plan This a SITEplan for is for TREATMENT a a complete health clinic. LATR I NES ---- i i i 27 In normal times, housing projects are more difficult to organize But than community projects such as schools and health clinics. such as an earthquake or flood, many people after a disaster, a time when they may be least are in urgent need of new homes ---at able to afford construction or to think carefully about their.new As a result, many agencies providing home's design without help. disaster relief have tried to design and build new homes for people ---only to find that the new homes stand empty‘because people don't This problem can be avoided if field workers use the like them. ideas suggested in this section to help families plan their own homes. As with schools and clinics, the smaller a house, the less it will usually cost to build. Here help their l l l BATH I NG are some guidelines to a family decide what minimum needs are: The plans for a house should clearly shah? where each of the family's basic activities Even will take place. the smallest home must have adequate space, either inside or outfor the family to side, sleep, cook, eat, and move around in comfort. I EAT I NG the family should consider including space in In addition, Latrines are especially its plans for a latrine and a shower. They can be designed important for every family's health. But there are several as part of the main house itself. advantages to building latrines as separate structures on an outdoor latrine For example, the same plot of land. can be moved easily when it fills up. Other activities laundry, prayer, a t:,A.ly may wish and private space. to plan space for include a family can save money by . When cost is a critical problem, using rooms to serve more than one purpose: for example, a single room can provide living and eating quarters by day, and sleeping space by night. 28 The following what kind of build. questionnaire can be used to help space they need and how many rooms a family determine they need to A. 1. SLEEPING SPACE How many people will sleep in your house? 2. Which people will share a bedroom with each other? (Write their names in the blanks for each roomi Room #3 Room #2 Room #l .- 01 ’ I ’ ’ 3. In the number circle to the left, of rooms needed for B. 1. DINING SPACE How many people will eat write the sleeping area. at your house? 2. Will they eat inside or outside? Will the eating space be attached or unattached to the house? (Check the correct boxes) 3. Can one of the bedrooms also be used for dining space? (If yes, leave the circle to the left blank; if no, write in 1.) C. LIVING/SOCIAL SPACE 1. Do you need space inside and/or outside for family members to spend time together or for visitors? 2. If so, can this living space be the same leave the If yes, as your dining area? box blank; if no, write the number of inside/outside rooms needed for living/ social spaces in the circle. Check if spaces will be attached or unattached.) D. COOKING SPACE 1. Do you plan to cook inside or outside your house? 2. Do you want the cooking space attached to the dining area or unattached? (Write the number of cooking spaces needed in the circle and check the correct boxes.) E. BATHjPERSONAL WASHING SPACE 1. How many rooms for personal washing do you need? 2. Will this space be inside or outside the house? Attached to the house or not? F. 1. 2. 3. b LAUNDRY SPACE Do you need space in the house for doing laundry? If so, will the laundry space be inside or outside the house? Will it be attached? Can the laundry space be in the same area as the bath? (If yes, write "0" in the circle; if no, write "1") 1 I O”T” O’“-” G. PORCH/VERANDAH 1. Do you need a porch outside.your house? If yes, write "1" in the If no, leave the circle blank.) circle! H. STORAGE SPACE 1. Do you need separate room(s) for storage? Will they be inside/outside,attached/ unattached? Write the number of rooms -needed in the circle and check the correct boxes. I. 1. OTHER SPACES NEEDED Do you need separate rooms for activities besides those listed For example, do you need separate for prayer, family meetings, or needs? If so, write the number needed and the purpose for each other above? space other of rooms one: - Check over your answers to these questions. you've listed should help you decide exactly kind of rooms/spaces you need to plan. The information how many and what WHAT SIZE WILL EACH ROOM BE? Ta be useful and comfortable, a room must be large enough and properly shaped for its function. For example, a bedroom must be long enough for a person to lie down in and wide enough so he or she can get out of bed and in and out of the room easily. A latrine, on the other hand,only needs to be large enough for a person to sit or squat (unless people also plan to dress or wash in the same area). The best way to make sure that a room will be large enough is to decide how large it would have to be for the largest adult likely to use or visit the home. Then the room will be comfortable for everyone. [Note: Often the proper size and shape of a room is determined more by traditional requirements and social patterns than by physical comfort. Field workers must be sensitive to the community's needs and priorities and should explore them thoroughly with the family.] Here are some guides - Most adults for will a "human" be less than measuing 2 meters unit: tall; - An adult usually needs 2/3 meter from side to side and from front to back in order to move around; and about 1 meter, or nearly half his/her height,to sit down. 2/3 m. l+=- 1 m. 31 USING MEASURING UNITS TO HELP THE FAMILY PLAN ITS OWN ROOM SIZES A family's interest and confidence in a building project will be much gre,ater if they are able to envision and plan their home's A first and very important way the field rooms themselves. worker can help them do this is to visit other homes in their community with them and question them carefully about their Some questions a family might want to ask include: reactions. . Do we want our rooms to be larger or smaller than these? . Would we like them to be the same or a different shape? a How do we feel about rooms with more than one purpose (for example, sleeping, dining, and living)? in, or 0 Are the rooms we have seen easy to move around difficult? l Is working in the kitchen or laundry space easy, or does it take a lot of walking back and forth? Do family members get in each other's way when moving from l Where and why? room to room? Once the family is familiar with a number of different possible designs, they will need to put the actual size and arrangement of rooms in their new home on paper. An easy way to help them get started is to give the family pieces Using 12 cm. for of paper representing the "human" measuring unit. 1 adult length is the most convenient.scale since. l/2 adult is an is 4 cm, The family ,even 6 cm. and l/3 adult will need pieces for: * the length and width of standing or lying down; an adult * the length sitting; an adult * the space an adult needs to side in order to walk and width of from side or work . * Remember that that they can needed. any furniture they have or special space needs in countries with cold climates, (for example, space may be needed for chamberpots in the bedrooms so people don't have to go out at night). the pieces be used to Extra copies NOTE: community group-are must be proportional to get an accurate picture of the planning pieces for Appendix 8. provided in A family can design its own rooms by gathering pieces it needs for any room and then arranging them into a square rectangle, or circle. For example, a bedroom one child a family for a couple would need: planning and ,, 2 pieces of an adult length and width for the couple's sleeping l 1 piece for the area; S-length child's . 1 piece f-length for an adult to . 1 strip the width adult for clothing storage: area: x $=-length sleeping x S-length sit; of an or . 2 strips the width of an adult for each parent to walk around their bed(s), and to walk to the baby's bed; 0 extra pieces for large furniture or other needs. one another so of the space use with a 33 Once the together possible experiment the family should try to put them pieces are gathered, so they form a room-shape. There are many combinations for any room, so people should be encouraged to with AF. many arrangements as possible. ALTERNAT IVES When all the pieces have been placed together, a line should be drawn around them. -This line represents the complete room‘113 If the shape of the room is irregular, the field worker should help the family make adjustments until it is a simple shape. FINAL CHOICE Space can be added to complete a square, rectangle, of the space in walking areas can be carefully up to l/3. or circle, reduced by Some f ADULT 3 ADULT + ADULT . To find of the first adult of the out what the dimensions final room should be, calculate the number of lengths along the sides room. Then the family, or if necessary, worker, multiply the number lengths by 2 meters. The answer will equal dimension of the wall the field should of adult the actual in meters. EXAMPLE:Caihduttin of Dimensions of Rectangub RoomAbove width: f 3 & 14 adult adult adult adult length length lerkjth ?engths x 2 meters = 3m Len&+ 1 2/3 l/3 2 adult adult adult adult length length length lengths x 2 meters = 4m RoomDGnensions: 3 meters x 4 meters Here are some additional measures that may be useful what pieces the family must use in planning kitchens cooking areas), and dining areas: l l Work space in kitchens, be about l/2 adult wide. to reach across; Space for fuel in by l/2 adult wide: . Dining person should kitchens especially Anything should in deciding (or outdoor counter space should wider will be hard be about l/2 adult space for each person (that is, space for the to sit and space in front of him or her to eat) be about l/2 adult wide and 3/4 adult long. COMBINATION KITCHEN-DINING l/4 ADULT %xg long 36 Let's look at how the "human measuring unit" can be used to plan several rooms. These suggested plans may be useful if a famJ.ly has problems picturing what they can do with the "pieces" for a room. worker may want to adapt these illustrations ( Note: the field if the furniture shown here is not relevant to the local area) PLANNING A BEDROOM FOR 1 PERSON TOP. VIEW I 11 ADULT LENGTHS I SIDE VIEW This is how the room might look. 37 BEDROOM FOR TWO ADULTS OR PARENTS AND CHILD OR A COUPLE I 1 &ADULT LENGTHS I 38 DINING/FAMILY ROOM 2 ADULT LENGTHS 39 Kitchens may be inside or outside: but in either case, they must be big enough to store all utensils and food away from animals, and to provide working space; at the they should be small same time, enough so that everything can be reached easily without many trips between supplies. Shelves and cupboards save floor space. In places where the kitchen is primarily for storage and most of the cooking is done the kitchen can be outside, smaller. _&-ADULT Latrines can be small: 1 m. X 1 m. However, if they are built longer, they will be easier to clean and to move around in. (See the separate section on latrines, page188 for more details). 1 ADULT SITTING Door opens in for privacy Bathrooms to require room dry oneself, to shower or and to get dressed. 1 ADULT LENGTH A verandah, or porch, is really a room with 2 or 3 sides open to the air. It should be big enough to be comfortable for social gatherings, family, prayers, or other meetings; this means at least one adult wide and one adult long (longer for large groups), so that there will be room to sit or lie down, and to walk around anyone using the room. 41 HELPING When the the next form the THE FAMILY DRAW ITS OWN FLOOR PLAN number and size of rooms needed have been determined, step is to decide how they should be put together to house. The easiest way to do this is to draw a picture of how the rooms would look from above if the roof were removed. Since it shows how the floor-space in the home will be divided among the rooms, such a picture is called the floor plan. One thing to keep in mind when designing a floor plan is to keep the shape of the building as compact and simple as possible. Odd shapes and sharp angles are more difficult and more expensive to build than either rectangles and squares. Curves are also expensive except when bamboo, or similar materials are used. the family's interest and confidence As in planning room size, a building project will be greater if family members participate in the drawing of their own floor plan. The field worker can help them draw the plan by giving them scale model pieces of paper or cardboard representing the rooms they have planned and helping them arrange the pieces in several different "floor plans". Each possible floor plan should be discussed at length in order to determine how well it will fit the needs of the family. When a final decision has been reached, the room-pieces can be copied on a single sheet paper then becomes the floor plan. arrangement of paper. of the This in 42 DRAWING THE FLOOR PLAN OF A HOUSE Here are some step-by-step small family's house might Sample Plan #l: House for examples of be developed. a couple A good way to start a floor plan, is to place the piece for the main bedroom (the room where the heads of the family will sleep) in the center of a sheet of paper. For a couple with no children, this might be the bedroom This suggested on page 37. size has the advantage that a first child could be easily accommodated without cramping. To this bedroom might be added a kitchen and a living/dining area (both kitchen and dining area are shown indoors here: if either or both will be the space required mciy outdoors, be very different). At this point been shown in illustration. doors the have not with how the no more floor than plan 1 child for a 43 Storage/Laundry The home could be built on tnls plan. But any of several changes or additions to complete the If grandsquare are possible. parents or aunts and uncles are part of the family, they may require the main bedroom; a second bedroom in which case, would be needed. In a nuclear family, a shower some along with can be added, storage or laundry space to complete the square: Or, the a porch: same space can be used as a latrine should be Finally, planned near the house, preferably where it will be sheltered from public view, Storage/Laundry Sample Plan #2: Holuse for a couple A less expensive alternative for the same couple would be to build a single bed/living-dining room using a screen to separate the two areas instead of a wall: with no more III Latrin than 1 child. 45 Sample Plan #3: House for a Small With 2-a Children, Extended Family or A Couple To design the floor plan for a slightly larger family, all the planner needs to do is add a new bedroom to the smaller homes shown in Plans#l and C2. For example, the verandah in Plan #l could easily be remodeled as a bedroom for two children or an aunt and uncle: . Plan #l could dining room, also accommodate the first bedroom, a new room either or the shower: Storage/Laundry Kitchen Bed room Bed room Dining next to the In Plan #2, the original bedroom can be converted into a room for two children or grandparents, and a second, smaller room for the parents could be added on the other side of the kitchen area. Kitchen Bath I Bed room Dining/Bedroom Sample Ijere.'s to if Plan 84: House for a family another plan for a family of the family continued to grow: Future -o-----w IT-------II II II II ‘I! Fut ure Addition of 4 or 4 or could be added Future II !! Addition Ki tchen Bed room Dining II ii II ii. II m----I.---* m-------- 11 II II II 5 that iition 1I. II 5, Bath POrch 47 .Some Points l to Remember About Floor Plans. The kitchen and dining areas should always be next to each other so that food can be carried If dining will easily from one to the other. the kitchen should have an outside be outside, door. In countries where privacy is important, each bedroom should be planned with separate access to baths and/or indoor latrines, so people won't have to pass through someone else's bedroom. standard floor plans In many countries, for various size homes are available from the government or local architects and But check to be sure that these engineers. plans are appropriate for lower income family needs! l A good way to find out what makes a good floor plan is to explore homes in the local area and copy or adapt successful ideas. Such a survey can be especially helpful in planning so that family members will not get in each other's way when moving about the house. 48 Doors, Windows, WHERE WILL and INSIDE Ceilings In All Buildings DOORS HE PLACED? No floor plan is complete until it shows where the inside doors between rooms will be placed and how people will move from room (For outside doors, to room. see the guidelines for windows and special notes on page 65. Inside to: doors should be designed l provide between easy movement rooms: l provide privacy (if desired). primarily Easy Movement depends They on the siae of the doors. should be one adult high, or and at least 75 to 100 2 meters, cm. wide for all rooms except bathrooms, which can have narrower 60 to 75 cm. doors, One other factor that can affect ease of movement is how-close doors are to other parts of the house. Doors should be placed so that they don't interfere with other open windows, or major doors, pieces of furniture (such as beds). Privacy depends on how much of a room can be seen through the doorThere is no problem when the way. However, it i.p door is closed. often desirable to leave the door open for air circulation. Privacy can still be maintained if the door is placed properly and opens in the right direction. The chart on the following shows the right and wrong to place doors in a room. page ways rF5-l Ii N a 49 Door Placement. Doors should of the inside INCORRECT: be placed--and of the room No privacy see into because room. hinged-so that as little as possible is‘seen when the door is open. passersby can CORRECT: View is blocked by door, al though it is left open for circulation. rn 50 Doors are shown the door in the Here plans in floor plans open position. of are some examples we've already seen: by drawing a line representing l how doors might be shown in the floor 51 HOW HIGH WILL THE CEILING Ceilings must be high that people can stand comfortably. The best follow is to keep the about l/3 meter above or about 2 l/3 meters BE? enough so up rule to ceiling the doors, high. If ceiling lights or fans are planned, then add about 2/3 more meters to make the ceiling at least 3 meters high. HEIGHT IF FAN OR LIGHTS ARE TO BE IN BUILDING AVERAGE In tropical areas, higher ceilings are significantly more comfortable if they are ventilated to allow heat to escape. Buildings with unventilated high ceilings HOT AIR COLLECTS AND IS TRAPPED NEAR CEILING tend to be very uncomfortable ..-. .-: . . . . . . . . , .- . ..L l . ,..-, *.~~..*y,..“‘.., * .* . ..-\. ;.. . . .:. ..: because heat collects in the i:Zj~‘3,~~‘~~“: .‘ii ;.r.;~i..~:oS.i : c;W..“; /‘~.I~~ :: space above doors and windows, i..g : y-y:,< ., .!.$ ;“‘.. : f i;> ) : ,.. . .: i !: :<.., . . . . .._...*... ::..:**.. &I i j ; : 1 i -’ ; . . ‘-: . . . . :‘:.y ...* . ..i making it difficult to keep the ..* .,.‘..... ;.. ::.*..- . ,. ~ i ” ...“‘-.. :‘:::’ :~‘:.:.i...” .’ -“..~ .., ; ; ; ; -..** :‘pj , .* : : : ui‘y? . . . . ..... ! :-.. rooms cool. .s .“.,I . ; ; ! : : ‘w..I 1: ,, 58 TAKE ADVANTAGE OF ANY BREEZE For noticeable must be windows wall. circulation, on more than there one The building should be placed so that the windows face intc light breezes, but away from and also away from harsh winds, the mid-morning/mid-afternoon sun. INCORRECT: Breeze CORRECT: Breeze can’t passes pass freely through through bu 59 Here are be placed position six situations showing how buildings in depending on the direction of prevailing relative to the equator. the tropics winds and should the NORTH OF EQUATOR Northeast or Southwest Windows face catch breeze as possible. All Other North and South to and avoid sun as much Winds. Windows face Northwest to avoid sun and catch much as possible /; ..“.~J Winds. and Southeast breeze as . ..p ..’ y..: *._. *- NEAR EQUATOR -.. . ...+* Due East ..:*..I; a ,. ,*.:, _ . ::-.:.. .:.+ . . . . I.I .-i-.1.1.1 .. .m..-.- :: . :‘: - . -. ..:-1.:‘. -“--‘\ ii.I 1*, % tIzl .‘..>:: ‘.. -... -..;. .-*, .,*-. -3 .:W:‘:.. . . . ...* y:‘, , .-. WestWinds. Windows face North and South as much as possible to avoid sun, but they catch breezes. All Other Winds. Windows face North and South avoid suni and catch breeze. to SOUTH OF EQUATOR Northwest -, ..a....* --.-: _ .<-:‘, *r =.* or or Windows face catch breeze as possible All Other Southeast Winds. North and South to and avoid sun as much Winds. Windows face Northeast to avoid sun and catch much as possible. and Southwest breeze as Another way to increase circulation is to use as many But bear windows as possible. in mind that: - building in labor windows as well can be costly as materials; - walls facing mid-morning or afternoon sun should not have more than one window per room (so as to reduce heat from the sun). Th,e size of windows also affects circulation because larger windows .allow more air in and out. Again, some cautions: - the larger the window, it will be to build: the more expensive - since there most likely will be times when the windows must be closed with shutters, they should not be much bigger than about 1 X 1 l/3 meters. Anything larger may put too much of a strain on the hinges and make the windows difficult to open and close; - large windows offer thieves or animals. less protection against 61 b One final consideration in getting the most circulation possible is the height of the windows. Most windows in tropical areas should cover the upper half of the wall so that any breeze will be felt around the head and shoulders. A few additional windows covering the lower half of the wall, especially in sleeping areas, will further increase circulation. Construction will be much simpler later if the tops of windows are kept level with the top of the door (about 2 meters). To sum up, a good would have: b plan for - windows sun; facing - shades, overhanging - several windows, flow through the facing mid-morning - large windows covering walls as possible plus of the walls, especially they are not too large - screens closed tokeep to keep away a building from roofs, in the a tropical mid-morning or climate and a verandah; placed opposite each other building (but no more than and mid-afternoon sun); out out mid-afternoon so wind can one on walls as much of the upper half of the a few windows in the lower half in sleeping areas; (make sure or heavy to open and close easily) insects, and shutters that rain, wind, dust, animals, can be and thieves. 62 WINDOWS IN A DESERT-LIKE Avoid Heat from The same rules to windows in Windows should and mid-afternoon. the apply tropical CLIMATE Sun. to be placed windows areas. to in avoid desert-like direct sun in areas as annlv the mid-morning Buildings in desert-like areas are often built around open courtyards shaded by trees and the walls of the building itself, so that windows open onto cooler air (the same idea is used too, but less often). in tropical areas, Buildings can also.be placed close together so that each shades the walls and windows of the building This may block some next to it. breezes, but since winds in the desert tend to be hot and uncomfortable, it isn't so important to keep buildings open to them. BUILDINGS SHADE EACH OTHER Windows in desert areas can also be protected from the sun's heat by designing them as openings self-shading walls. in thick, \ SIDE\/IEW’ sutd CHINES 0~ OUTS1 DE WALL BUT LITTLE Protect since Windows so= ~nc-l+ --w-a from Uncomfortable w winds =s--*- HEAT & LIGHT ENTER BUILDING Winds. hot and uncomfortable, people want to be protected from them rather than exposed to them. On the other hand, a building with no circulation at all would be uncomfortable and unhealthful. The best way to protect against uncomfortable wind without cutting circulation entirely is to plan small windows opposite each other. .SMALL WINDOWS ;:: ,: i:iiI /a' ,: :I ii.-, .,t : Protect Windows from Dust and Glare -- In many areas, the ground tends to be dusty. because it is often bare and light in color, in strang glare that can be very uncomfortable. it In addition, reflects sunlight Both dust and glare can be effectively guarded against by placing smqll windows high up from the floor. This prevents most of the dust picked up by winds from getting in, and blocks all the glare. 65 D a good To sum up again, climate would have: - windows afternoon - small, direct - windows EXTERIOR plhn and doors sun; deep-set light; placed for facing windows high to a building away to from protect protect in a desert-like mid-morning against against and midhot glare winds and and dust. DOORS Like windows, mind: exterior doors should be designed with climate in a they should be placed to avoid heat from the sun; they should be shaded from rain if they open outward, or they should be designed to open inward (otherwise weather will. spoil the wood or bamboo and cause the door to twist, warp, or rot): I generally it is worth the expense to shade doors so they can be opened outward since this is safer in emergencies and increases the amount of such as fire or earthquake, useful space in the building; a in earthquake areas, outside doors should be placed close to the center of the wall's length (see the separate section on earthquakes (page 196). l b -- CONSTRUCTION Schools, clinics, number of materials. MATERIALS and homes can The proper choice of materials considerations, including: . the 0 climate: some materials the part of the some parts need be built depends cannot out of an almost on almost as many withstand large building (floors, walls, roof, to be stronger than others; endless Q rainfalls; etc.): 9 the builder's budget: some materials are much more expensive than others for original construction, maintenance and future additions; working on the construction: some I the number of people materials require many more people than others; . the amount of time available for materials take months to prepare For any application, .choose from that will limits of the builders. important consideration available at or near always less expensive, use the building, and construction: properly. some there are usually several materials to be within the budget, time, and labor Whenever there is a choice, the most is what materials (and equipment) are the site. Local materials are almost more acceptable to the people who will more familiar to those doing the construction. This section is designed to review basic information most common materials that small rural communities to find nearby. Detailed directions in the use of will be found in later sections covering the actual process (pages 115-180). But once builders know discussed here, a brief will usually be enough the major characteristics survey of what is locally to decide what to use. 4 about the are likely these materials construction of the materials avaiiable a 67 Rammed Earth (Mud, Pise) and Adobe Blocks Rammed earth is a combination of sand, silt and clay that properly pressed and dried is suitable for walls in dry (wet climates, too, when protected with lime plaster.) sand, silt, and clay are locally available, rammed earth adobe blocks are two of the least expensive materials to when climates. If the and use. Basically, by volume: ratio the ingredients l 50 to 80% l Up to 30% clay; . 15% silt The amount determined a mud that sand (the (extremely are most mixed with water in this important); fine-ground rock). of water needed varies considerably and must be by making several tests. There should be enough holds its shape but can still be molded, to make @nce the ingredients are mixed thoroughly, they are pounded with a thin pole into a portable mold (form) 2/3 to 1 meter high until they are packed solid. The mixture is then allowed to cure (dry) thoroughly. When one section is ready, the mold is removed and used to' form the next section RAMMEDE ARTH FORM W CRETE/BLOCK FWN DAT I ON Adobe bricks are individual solid mixture of ingredients as rammed blocks earth. made from the same A simple form - or mold is used to shape the bricks, which must be dry for at least a month before use. Because of the drying time needed, adobe bricks can only be used where there is a long season of hot dry weather. ADOBE FORM \I Construction and highly especially volunteer with either rammed earth or adobe is inexpensive labor intensive. This makes both materials good in low-income communities that can contribute labor. Rammed earth and adobe should never be used underground foundations, since underground moisture will eventually them. Both materials are excellent for walls, however, withstand rainfall if protected with lime plaster. In earthquake areas, with wood, wire, or rammed bamboo. earth and walls must Finally, rammed earth and adobe structures cannot roof loads without strong wood or iron reinforcement. roof materials, such as thatch or bamboo, are the with either rammed earth or adobe brick walls. for weaken and can be reinforced support best heavy Light to use 69 Wood wood is one of the most versatile and durable construction materials. It is easy to work with and can be used to build almost any part of a structure. Due to deforestation of many countries, however, wood is too scarce and expensive for use by most low-income communities as their main construction material. Field workers in countries like Thailand or Malaysia where wood is still plentiful may wish to consult one of the many excellent books-describing wood frame construction listed in Appendix 7. Over the long-term,projects to re-plant forest replenishable source of wood for construction desirable. But most communities now will only wood as a secondary material for: . . o . . e areas as a (and fuel) are highly be able to afford roofs; doors and door frames; shutters, windows, and window frames; porch railings and posts; wall reinforcements (especially in earthquake forms for poured concrete, blocks, temporary braces, and scaffolding for roof construction. The best timbers some resistance to use are generally those to decay, rot, and termite - Lignum vitae (West Indies) - Honduran Mahogany - West African Odum and Okan - Asian rosewood and teak. Some softer woods, such as Eucalyptus Pine, When in doubt, a survey of nearby buildings which local timbers have proven successful. that attack, areas) frames and are hard and such as: have denya are also quite good. may help to determine ‘d Bamboo is an excellent material except the foundation. Where inexpensive. Its light weight generally easier than wood. Bamboo must be used with great loads or excessive water, it cannot be used for almost any part of a building available it is usually very makes it very easy to work with-- care, however, because it cannot support dampness or rain. Because it decays in underground for a foundation. Since construction with bamboo is very with other materials, it is covered in beginning on page 181. different a separate from construction section 70 Stone and Rock Piles of stone and rock can be used to make strong foundations and walls, especially if used with a cement-based mortar to hold them firmly together. Stone and rock disadvantages, l have several however: if not locally abundant, they are expensive to obtain; e walls made with rock or stone have many uneven surfaces. Filling in the large cavities in order to made inside walls smooth is time-consuming and expensive; o walls of rock/stone must be thicker than cement block walls if they are to be equally strong; l building to precise measurements is difficult or impossible; builders planning to use rock/stone should plan slightly larger rooms and construction sites to ensure that the finished building will be large enough. Cement and Materials Made With Cement Cement is an adhesive material that l'bondsV' or glues objects such as rocks or grains of sand together so that they form a strong permanent piece. A useful cement can be made locally from finely-ground limestone. But commercial cement:; also contain silica, alumunum, and iron oxide. These materials ensure that the mixture will contain a variety of grain sizes The more different grain sizes there are! the stronger the cement will be. 71 cement is Because of its bonding action, in many construction materials including: . mortars l concrete - poured - reinforced . blocks - concrete blocks - sand-cement (sand-Crete) blocks - stabilized earth blocks Each of these materials is cement is used Generally, as an ingredient in a blocks, or stones,and . as an ingredient in discussed used as an ingredient below. two ways: (pastes used mortars, to plaster walls); concrete. to bond bricks, Mortars Mortar is a general term for any mixture of cement with sand and either lime or clay. The ingredients are mixed in varying proportions with water to form a paste that can be used: - to bond rocks; - as a wall stucco). bricks, finish The tables in Appendix recommended proportions different mortar uses. blocks, or (plaster, 5 give for Concrete Concrete gravel, together cement. is a mixture of sand, and water that is held and given strength by The strongest concrete has particles ranging from very fine across sand to gravel of 3.75zeters rs Some builders and manufacture refer to the sand as fine and the gravel as aggregate, coarse aggregate. ENLARGED CROSS SECTION Of CONCRETE 72 wood forms must be carefully Before concrete can be poured, When the built to hold it in the exact size and shape desired. formwork is ready, plain wet concrete is mixed, poured in the and allowed to cure (dry) for a few days to a few weeks forms, (depending on the weather and type of construction). Plain poureu concrete can be used to build: footings (pads of concrete a foundation building's weight over a wide surface); . blocks for foundations that distribute a and walls; . floors. and gravel vary according to The proportions of cement, sand, But these proportions are the planned use of the concrete. For example, always referred to in the same way by builders. 1:2&:3, means concrete a formula often used for foundations, composed of 1 part cement, 22 parts sand, and 3 parts gravel. A builder usingthis formula would need 24 wheelbarrows of sand and 3 wheelbarrows of gravel for every wheelbarrow of cement. In addition, he/she would need approximately 23 liters of water to be added to the mixture. Reinforced Concrete Reinforced concrete combines materials with oppositecharacteristics: two . plain, poured concrete: resists downward pressure (compression), but will not bend; it cracks instead; . iron have will CONCRETE ALONE IS NOT STRONG ENOUGH s will bend (they rods: tension strength), but they buckle under compression. Reinforced concrete is prepared and handled as plain concrete is, except that an iron rod, or a series of rods,is fastened inside the form before the concrete mixture (In some cases, is poured in. bamboo stalks can be used for reinforcement in place of iron rods. See -page 188). a 73 D Reinforcing concrete or bamboo is fairly multiply the strength 2 to 5 times in: either with iron easy and can of the concrete walls; support walls and ceilings; un-supported such sections as overhangs of or balconies. Blocks A variety of blocks can be made by combining cement with other ingredients. All these blocks are useful for foundations and walls and can be produced locally if the proper ingredients are available. They can either be made by hand or with a simple press. A press is generally more efficient and produces a stronger, more tightly-packed block than can be made by hand. Whether made by hand or press, the blocks can be solid or hollow, depending on the mold chosen. Hollow blocks use considerably less material, reduce weight, and improve insulation. They are not as strong as solid blocks. But in sections of a building where additional strength is required, the hollow parts can easily be filled with poured concrete or other reinforcing materials. TWO BASIC BLOCK-MAKING PROCEDURES J/By By #l #2 #3 Hand. #l Gather and Mix Ingredients #2 Pour Mixture in a Mold #3 Pack Mixture Tightly in Mold with Shovel #4 Add More Mixture and Pack Again #5 Remove Mold #6 Cure (Dry) Hand-press. Gather and Mix Ingredients Pour Mixture in a Mold Pack Mixture Tightly in Mold with Press #4 Add More and Pack Again #5 Eject Block from Press 86 Cure (Dry) 75 B Concrete Blocks Concrete blocks are excellent for foundations and walls. They are made from a mixture of 1 part cement, 2 parts sand and 4 parts gravel. As manufactured commercially they: are usually among the strongest blocks available (in fact, they are stronger than necessary for l-story buildings); l l have excellent qualities; insulating . are the most uniform blocks (important for accurate, durable construction). However, expensive use. B they are by far the most block a community could Concrete blocks can be made locally if limestone (or commercial cement) sand, and gravel are available in large quantities near the site. The process is simple, but timeconsuming. Generally, the blocks must be made about a month before they can be used for construction. Sand-Cement Blocks Sand-cement blocks parts sand. They some reinforcement, buildings. (Sandcrete) are strong blocks made of 1 part cement to cannot be used to support .roof loads without but are more than adequate for l-story 6-8 Because of the high proportion of sand needed, sand-cement blocks are only practical for construction where there is a lot of sand (sand-cement blocks are not generally made commercially). But if the sand is available, sandcrete block-making is a quick and efficient process. Sandcrete blocks only take 12 days to cure (dry), less than half the time required for concrete blocks. 76 Stabilized Ezwth Blocks These are blocks in which clay soil, rather than sand, is mixed cement or lime. with either The amounts of cement and soil needed for a good mixture can only be determined by testing how much the soil shrinks when dried (the procedure is simple and can be followed easily by any community group). The blocks are formed in the same way as sand-cement blocks and can be used for all the same purposes. They are especially suited for lowcost construction in areas where sand is not available in largeenough quantities for sandCrete. However, great care must be taken to keep organic material out of the clay soil used in the mixture. Otherwise the mixture will not form a strong bond. (This too can be done with a simple test of local soil samples. See page 146). Stabilized used after earth only blocks S days can be of curing. Summary In surveying in mind that: l . 0 l l locally available adobe brick is best concrete foundation materials, for dry, hot and protection sand-cement blocks require cement and stabilized and about the right but require materials; are strong and a lot of sand; earth blocks are cheaper as strong; but care must mix of soils is available . concrete blocks are good but very commercially; they can be produced to prepare; is areas but against rammed earth walls, though made of adobe brick walls, are not as strong stone and rock are good than other construction it the or needs rain; to keep a rock same ingredients as permanent: more easy useful to heavy, make, hard but than sand-cement be taken to see in the area; expensive locally if but or as work they blocks that purchased take a month 77 plain poured concrete is a strong and versatile material especially suited to foundation footings, foundation walls, it can be made inexpensively in most communities and floors; if limestone or commercial cement is available; reinforced material earthquake of concrete is the all (especially areas). But it strongest, longest-lasting in wet and stormy climates is ~eryexpensive. and IhED PLANNING FOR C!QNSTRUCTION 8C After the size and floor plan of a new building have been decided on along with its site and position; and after a preliminary assessment of the construction materials that may be used has been made, the next crucial step is to develop detailed written plans (or blueprints) to guide each part of the construction. These plans must answer several questions about each part of the building from the ground up: FOUNDATIONS l How deep in the . How thick . How high must . What will reinforced? the ground must it must the foundation be set? be? it be? foundation be made of? Will it be FLOORS l Will the floor be made of . How much should ground? . How thick it cement be raised should it or above packed the I i earth? level of surrounding be? WALLS * What will the . How thick should l walls be made of? they be? Should How will window and door frames they be placed in each wal:? they be reinforced? be made and exactly where several angles? ROOFS . What will l Will it the be flat, roof be made of? set at an angle, or set at will 81 Many design walls roof plan make walls of these questions are interrelated. For example, the of the foundation depends in part, on the weight of the and roof it must support; and the design of the walls and in order to depends, in turn, on the foundation. Thus, the construction effectively, the builder must be able to some basic decisions about either the foundation or the and roof before determining all their exact specifications. When in doubt about a detail of the construction plans, the field worker or community member may want to seek advice from an experienced local contractor. In most cases, however, construction plans ~o~be drawn successfully for simple l-story buildings by anyone following the suggestions in this manual. This part community of the manual member, is designed to help the field worker or Q first, to understand key methods/principles and key technical characteristics of basic of construction materials; . how these principles basic design; and second, to proceed and characteristics . third, plans. to actually step-by-step to should influence draw his/her consider their own detailed construction 82 PLANNING FOUNDATIONS If the walls of a building are built directly on the ground the weight of the surface, building will soon press them into the earth. This causes the building to sag, crack, or leak. r --mm----t WALL II Foundations are strong platforms built below ground level, where they won't sink. A building with a foundation can "stand" securely. 1I I b FOOTING I L- -e------ I i PLAN VIEW The foundation of a wellconstructed building does several things: it provides a level for the building to l a it if or l helps earth rains it keeps ness. platform stand on; protect the building tremors, strong winds shake the structure; out water and dampELEVATION Here's a list of things foundation must NOTdo: l sag; l dissolve l crack l slip l buckle (or from rot) stress the NOTE: The footing around the by water at erosion; a certain on uneven ground under pressure of water ground (this is called "scouring"); in the . collapse from the building. the VI EW weight of point; continues building wall can be made of many different materials. Each material must be planned for in a different way. There are other foundation designs such as pier and beam, or post and beam that communities with access to heavy wood beams might wish to use. See Appendix 7 for reference materials that discuss these designs. Note: INCORRECT: not square Footings All foundations should have a footing. The concrete can be poured directly into the foundation trench, or into wooden forms in the trench. In either case, the bottom of the trench must be ZeveZ and the sides of the trench or of the kooden forms must be square: that is, they must be exactly ,vertical, at 90° to the trench bottom. emcrete TRENCH 5cm x 1Ocm spacer to secure the form L 5cm x 1Ocm or 5cm x 25cm boards angles to the trench botLzi” ang1e’ at right 247-801 0 - 77 - 7 CORRECT: square 84 The depth the footing of the rests trench in which depends on: . what the foundation wall is made of; . the stability and strength of the soil: line (this only applies 0 the frost in areas where temperatures drop below freezing in winter; the frost line is the maximum depth to which soil freezes locally); 4 the unevenness and/or slope of the ground. The wCdth and thickness footing depend the foundation Foundation on what wall is of the material made of. Walls The foundation walls can be made of rock, or they can be made of blocks of concrete, sand-cement, or stabilized earth. All of these materials are strong enough to support the walls and roof of most l-story buildings. The choice depends on *what materials are available, the builders' budget, and whether or not earthquakes or severe weather conditions will require reinforcement in the foundation. INCORRECT: Rock Foundation Walls. A rock foundation wall is built by setting stones that are 20 to 40 cm. long in mortar. The rocks must be cleaned so that no rocks remain on them. AZ2 the spaces between the rocks must be filled with mortar (these spaces are called "joints"). In addition, and most important, they must be laid so they overlap. If a straight line can be drawn between the rocks from the top to the bottom of the wall, a crack will develop. A crack CORRECT: Overlapped wi 11 develop. is more durable. 85 Rock foundations are the least However, they expensive to build. require a large number of rocks, and it is difficult to clean, and overlap the rocks level, properly. If the building position is on rocky ground, or on dry, wellpacked clay soil, the footing for a rock foundation wall should be 4 to 8 cm. thick. In less stable soils, such as the footing sand, or gravel, should be at least 10 cm. thick. In soft black soil, drained and made earth, the marshland, footing should be reinforced and should be 10 cm. thick. In rocky or hard-packed clay soil, rock foundation walls need only be In other soils, 30 cm. deep. they should be at least 45 cm. deep. Rock foundation walls should be at least 30 cm. thick, and they will be much more stable if they are flared at the base to 45 cm. Whether Block Foundation Walls. built of concrete, sand-cement, or stabilized earth,.block foundal tion walls are made by laying level rows of blocks on concrete footings until the wall reaches the the planned height of the floor. Each row of blocks, called a cowse , is joined by mortar, as are the ends of each block. Block foundations cost more to build than rock foundation walls (except in areas where the rock must be transported over large distances), but block foundation walls can be put up faster, and they are easier to build well. M 4CM 45cm 86 In rock or firm clay soil, a block foundation should be 45 In less stable to 60 cm. deep. a block foundation shouZd soil, NOTbe used. The width and thickness of the footing depend on the size of the In general: blocks being used. . the footing should be as thick as the blocks are wide; . the footing should be as wide as the blocks. 3 times The frost line is the Frost Line. depth to which the ground in any area freezes in the winter. In climates with freezing temperatures, the footing must be entirely below the frost line. The table depths to frost line below gives suggested be safely below the in different climates: Lowest Temperature in Winter, Degrees Celsius Safe Minimum Depth for Top of Footing -lo 45cn. -so 75cm. -1lO 90cm. -18O 1.05m. -22O 1.2om. -28O 1.30m. 87 D Ground. If a building Sloping -will tend to slide downhill, Thus if to slip and/or crack. or is uneven, the trenches for completely levelled. --------- ---- --- is built at an angle on a slope, causing the foundation and walls the ground under a building slopes the foundation footing must be DIRECTION ------- If the ground slopes sharply, it "step" the trenches. When block it's important to make each step of blocks. OF SLOPE b ---------- --- may be easier, or necessary, to foundation walls are planned, the height of one or two courses 88 Deciding Upon the Ma+-Gals and Qimensions for Foundations In general, the best way to decide what the foundation walls will be made of is to choose the least expensive and most easily accessible material. Once the choice has been made between rock and blocks, the depth of the trenches and the dimensions of the footing and foundation wall may beqprozimatety determined by using the figures outlined on pages 85-86. It is important to remember, however, that these preliminary figures are only approximate guidelines. Any number of local conditions can make a deeper, stronger foundation advisable. One of the best ways to determine whether preliminary foundation plans are safe is to compare them with the foundation structures of buildings in the local area. The field worker or community member should ask: , How deep are the foundations of buildings that have cracked walls or other signs of weakness? How deep are the foundations of buildings that have lasted well? 0 How wide and thick are the foundation of weak buildings ? Of strong buildings? footings and walls . What are the foundations of weak buildings made of? are the foundations of strong buildings made of? What If preliminary plans for the foundation are similar to those of strong buildings built nearby on the same kind of soi1.i.n the local area, they should be safe to use. If the preliminary plans are similar to those of weak buildings they should be strengthened before the start of construction. Drawing Final Foundation Plans After the materials and dimensions of the foundation have been planned, the last step before construction of the foundation can begin is to draw a final foundation plan. The plan drawings: should include two simple - a scale drawing of the footing and foundation wall as they would look in a cross-section; - 4 -W FOUNDAT I ON WAL: FOOT I NG Q 89 - a scale drawing of the footing and foundation wall measurements as they would look if seen from above. Both these drawings are simple to Step-by-step produce with a ruler. instructions will be found in Appendix 2. I OUNDAT I ON WA tl E 9 90 To be comfortable and safe, the floor of a building must be: 0 dry; . level; l smooth, but not slippery: movement should not be obstructed by holes or bumps, but the surface should not become slippery when wet. The most important keeping the floor of these dry. is In many climates, the ground under a building will be damp, even in periods between rainfall. WATER In areas of heavy rainfall, if the floor is at or close to ground level, water will come in under the doors and damage the floor. For both these reasons, the floor of all buildings in areas where there is heavy rainfall should be raised at least 20 to 30 cm. above ground level to protect it from moisture. The best way to do this "dry fill." Dry fill is of any material that will water. Typical materials dry fill include: small broken bricks, clumps of earth, and gravel. Types is with a layer not hold used for stones, hard ICORRECT: Raised of Fkxws Two basic types of floors will discussed in this manual: . hard-packed earth floors, 0 concrete. In areas supplies, good. with large local wood wood floors are also be to Prevent Flooding D HARD-PACKED EARTH FLOORS Hard-packed earth floors are much less expensive than concrete. They are adequate in dry climates, but can be uncomfortable and unhealthy in wet climates or lowlying areas, even when ample dryfill is used. Earth floors must be made from hard earth taken from below ground Soft topsoil, or any soil level. containing organic material will The hard not pack well enough. earth should be placed above the dry fill in a tightly-packed layer lo-15 cm. deep. CONCRETE FLOORS Concrete floors cost more than hardpacked earth. They are also stronger and much better-suited to wet climates and low-lying areas. A concrete floor is made simply by pouring a layer of concrete over the dry fill.(Hard laterite is the best kind of fill for a concrete The.best thickness of the floor.) concrete layer depends on the planned use of the floor (see table on right). I Suggested Thicknesses of Concrete Floors Purpose floor house, school of Thickness cm. clinic, 10 garage (for vehicles) 12.5 farm storage (heavy equipment) 15 92 In locations where the ground is very unstable or uneven, earthquake zones, a concrete floor might need reinforcement flexibility and additional strength. Estimating To ,to the of for the Amount of Concrete Needed for or in for a Floor. determine whether the builder can afford a concrete floor, and be sure of buying enough materials without buying too much, field worker or community.member(s) should make an estimate how much concrete will be needed. Step-by-step instructions the calculations needed will be found in Appendix 3. PLANNING WALLS, WINDOWS, A cqlete, detailed walls (both exterior of: AND DOORS plan for the construction of a building's and interior) would include descriptions l the material they'll l their height; l their length; . their thickness be made of; placement of windowsp doors; _I . the construction techniques to be used, especiallyaround doors and windows, and where any two walls meet; l l the exact the use of reinforcement (if withstand the stress of very earthquakes: a an estimate construction. of the any) soft to help ground, amounts of materials The basic plan and design of the walls already specify many of these features, the outer walls will be made of, their placement of doors and windows. the building high winds, needed or for developed earlier should especially the materials dimensions, and the exact However,, especially when blocks or bricks will be used for the walls, some changes may have to be made before construction can begin. To avoid expensive mistdkes or problems during construction, a detailed construction plan of the walls should be prepared. 93 B Wall Height end Length When the walls will be made of rammed earth, stone, concrete, other than block or bricks, the bamboo, or any other material height and length of the walls should be exactly as planned in the basic wall design. However, when using blocks of any kind (adobe, sand-cement, it may not be possible to build a wall exactly cement, etc.) height and Zength planned. B if the blocks used will For example, measure 12 cm. high, a wall could be 2.88 meters (24 blocks) high or 3 meters (25 blocks) high; but it couldn't be 2.96 meters high unless one layer df blocks was and this is difficult cut in half, to do. In the same way, if the blocks used will measure 40 cm. a wall could be 7.20 meters long, (18 blocks) long or 7.60 meters (19 blocks) long; but it couldn't be 7.35 meters long unless one block in each layer of the wall were cut 5 cm. short. 2.88m (24 Blocks) the - 211 and much less expensive if the Construction is much easier, height and length of block walls are adjusted so that they can be made from a whole number of blocks. To determine how much the height and length of the walls to be adjusted (if at all) simply follow these steps: STZP I: needs Divide the planned height of the wall .by the height of one block. If the answer is a whole number, the wall can The result be built as planned without any adjustment. of the division will equal the number of layers (courses) of block needed to reach that height. Example: The planned height of the.waZZs us&~-22 cm.'high bLocks: Ls 2.88 meters 288 i 12 = 24cou.rses (288 em.); of blocks If the answer is a whole number plus a remainder, compare the remainder with the height of one block and round off to the nearest whole block. 94 Exam@?e: of the planned he ks high. STEP 2: The procedure for adjusting the length of a blor?k wall is similar to the procedure outlined above for adjusting the height: divide the planned length of the wall by the tength of one block. If the answer is a whole number, with no remainder, the wall can be built as planned without The result of the.division will equal any adjustment. the number of blocks needed to reach that length. #!iMlpZe: If the ~~LVUWI length of the natt is U8iw 40 an. hq blocks: 720 ; 40 = 18 blocks 7.2 meter8 (720 Qn. i, Zag If the answer is a whole number plus a remainder, compare the remainder with the length of one block and round up or down to the nearest whole number of blocbs. Wall Thickness The thickness l of a wall on three things: whether the wall is exterior or interior: interior walls. usually do not support the weight of the roof and can therefore be thinner; interior walls also play a less important role in insulating the building from heat and cold; . what the wall can be thinner l depends the climate: walls, while walls. is made of: than walls buildings buildings walls made of stronger materials made of weaker materials; in desert-like in tropical climates need thicker climates need thinner 95 The table below suggests minimum thicknesses for different kinds The figures given should be adequate for most l-story of walls. However, if there is any doubt buildings (up to 5 m. X 9 m.). about the load-bearing capacity of the walls in a special design, advice from an experienced local contractor should be sought. SUGGESTEDWALL THICKNESS FOR DIFFERENT MATERIALS Exterior Material 37.5-45 cm. 30 cm. 12.5-20 cm. Rammed Earth Adobe Brick Poured Concrete (not reinforced) Poured Concrete (reinforced) Stone Block (sandcement, stabilized earth, cement) Placement of Doors Wall 12.5 cm. 30-37.5 cm. 20 cm. and Interior Wall 37.5-45 cm. 30 cm. 12.5-20 cm. 12.5 cm. 25 cm. lo-15 cm. Windows As with the height and length of walls, the exact placement and size of windows and doors may have to be adjusted to make construction easier. No adjustments need to be made when the walls will be made of rammed earth, stone, concrete, bamboo, or any other material other than block or brick. However, when using blocks of any kind (adobe, sand-cement, cement, etc.) the size and placement of windows and doors should be planned,so as to make them even with the courses of blocks. ADJUSTING THE SIZE OF WINDOWS, DOORS The procedure for adjusting the height and width of the space for windows and doors is exactly the same as the procedure for Simply think of the adjusting the height and length of a wall. windows and doors as though they were walls to be built with blocks. Then, following the procedure described on pages 93-94, increase or decrease the height and length of the windows/doors as necessary. For example, suppose a window is planned so that it will begin 135 cm. from the bottom of a wall made of 10 cm. high x 20 cm. thick x 40 cm. long blocks. 135 cm. would be 13s layers (courses) of blocks high. So rather than cut a whole layer of blocks to fit the window height, it is much easier either to raise or lower the window 5 cm. so it will start 130 cm. (13 courses) or 140 cm. (14 courses) from the bottom of the wali. Construction Details for Dams,, LOCAT I ON LOCAT I ON Windows, an,d interior DOOR AND WINDOWFRAMES The construction plan for walls should show how the door and window frames will be attached to the walls. Window and door frames are made of wood (5 cm. thick wood is best) to fit the exact size of the wall opening. The frames are permanently attached to the walls, and then the windows and doors are attached to the frames. WINDOW FRAME DOOR FRAME Walls Frames that are nailed right to the masonry or concrete of the wall are the best for preventing drafts and But they may also be leaks. attached to the wall by placing wooden slats in the mortar joints and nailing the frame to the slats. WINDOW FRAME LINTELS Lintels are short beams that should 'always be used to support the wall over an opening for a door or window. Lintels are usually as thick as the wall. In rammed earth or adobe brick walls, the lintels may-be made of They 5 cm. thick wood beams. should extend past the window or door opening about 20% of their length, or a minimum of 2C cm. on each side. In walls made from any other material, except bamboo, the lintel should be made of reinforced concrete (use two steel bars for Construction reinforcement). will be much easier if the lintels are "pre-cast": that is, made in advance and then placed in the wall like a brick. (For bamboo, see the section on bamboo construction, page 181) In block walls the lintels should overlap the opening 3 the length of a block on either side of the frame. l -T- I I INTEL IN WOOD FRAME REINFCRCEMENT BARS 98 INTERIOR WALLS RECOMMENDED Interior, or "partition" walls do not support the weight of the roof, Thus they as the exterior walls do. are often thinner than the outer or made of 'a different walls, However, they material completely. must be attached to thrt outer walls. This can be done after the outer But it is walls have been built. usually better and easier to build all the walls at the same time. This is especially true when the walls will be made of blocks or bricks. The wall construction plan should include a diagram showing how the partition walls will be attached to the outer walls= REISJFORCBMENT . EXTERIOR WALL m( -NOT EXTERIOR WALL A INTERIOR WALL RECOMMENDED: WEAKER , , .. . . In areas where buildings are exposed to stresses suqh.as high winds, severe storms, freezing and high humidity, temperatures, walls should be reinforced. Effective reinforcement will increase the life of any building significantly. Often it enables the builder to construct thinner walls and save money on materials. In earthquake areas, walls MUST be reinforced. (See the,section on construction in earthquake 'zones for special reinforcement techniques not shown here, page 195). _, Rammed earth and stone walls are very difficult to reinforce effectively. Block walls can be reinforced in several ways: l steel rods can be run along the horizontal joints of the wall.: the rods should be.1 to 1.25 cm. thick: where they overthe overlap should be at lapI least 25 cm. .lN RE I N FORCEMENT BARS MORTAR JOI NTS (overlap 25cm Minimum) 99 . barbed wire is an effective reinforcer: it is run, like the steel rods, along the top of each course of brick: . if hollow blocks are used, the holes in the corner blocks can be used to run steel rods from the foundation up to the roof; then the holes can be filled with concrete; REINF RING RE INFORCEMEN TOP OF .a "ring beam" can be run around the top of the walls: this is usually a 15 cm. thick band of concrete with 2 steel rods that runs continuously (without seams) around all four walls. Ping beams are mandatory in earthquake areas. (See page 200). RE I N FORCEMEh-J’ BARS Poured concrete walls are often reinforced; the exact thickness and arrangement of the reinforcement bars should be determined by an experienced local builder, but this is the method most commonly used: Steel rods ranging from l-2 cm. are arranged horizontally and vertically, lo-20 cm. apart. They are fastened to each other by lightweight flexible wire and are wired in place temporarily until the concrete is poured. Concrete that has been reinforzed has from 2 to 5 times the strength of unreinforced concrete. This means that, for example, a 10 cm. thick reinforced concrete wall will be as strong as an unreinforced wall twice as thick. RE I NFORCEMENT RODS . POURE:D CONCRETE w ESTIMATING MATERIALS tiEEDED TO BUILD WALLS Before construction can begin, the builder needs to estimate how much of each of the materials to be used will be needed so that all the supplies can be purchased or assembled in time. Details of the calculations involved will be found in Appendix 4. PLANNING ROOFS When the basic design and construction plans for the foundation, and walls are complete, the field worker and community floor, member(s) should consider what kind of roof the building should have and how it will be constructed. Each can be made of different There are several kinds of roofs. and each has advantages and disadvantages, depending materials, on the climate, the builders' budget, the availability of materials, and the ease of construction. To make a good decision about the kind of roof to be used, the builder needs to know: . the basic roof styles; for the local climate their advantages and environment; . the kinds of materials for each roof style; 0 how to design roof style. Roof Styles and suitable and build Their and disadvantages each Functions All roofs provide protection from the el?Fiii?nts: sun, rain, wind, dust, heat, cold, and animals and insects. But each different kind of roof protects against some things better than others. In addition the different roof styles vary in their durability and ease of construction. There are @flat: across walls; . shed: angle, four basic roof r FLAT ROOF styles: the roof simply lies flat the top of the building's SHED ROOF the roof is built at a slight generally from lo-30". l the roof a triangle over the building, dabie roofs are a combination of each starting from two shed roofs, the opposite sides of the building with the same angle or pitch, hence, "double-pitched"; I hipped: hipped roofs are gable roofs that have been pitched on the ends of the building as well as the sides. HI P!‘ED ROOF gabZe or double-pitched: forms l FLAT ROOFS Flat roofs are generally the most difficult to build and the least suitable of roof styles, especially in buildings wider than 4-5 m. Here are some of their disadvantages: principal . because they are flat they tend to sag in the middle unless given very strong support: the most common forms of support, wooden or reinforced concrete beams, must be heavy to be strong: as a result they are difficult to lift into place; reinforced concrete or heavy woodcotwmrs may also be used to support flat roofs. However, columns reduce usable space inside the building; . flat roofs tend to hold snow or rain; this increases the weight on the beams and walls and leads to leaks and warping; . flat roofs tend to lift in wind and must be securely tied to the building; in areas with severe storms, flat roofs are dangerous. The only advantage of flat roofs is that they can provide extra living space above buildings in dry, desert-like areas. I I GABLE ROOF 10 3 SHED ROOFS Shed roofs are generally easier to They are support than flat roofs. usually the least expensive and the easiest style of roof to build. Because of their pitch (angle), they shed water easily and are particularly good in warm, rainy climates with no snow. Shed roofs are slightly less subject to wind pressure than However, in stormy flat roofs. areas they must still be very securely tied down to the walls. G-ABLE ROOFS Gable roofs use more materials, require more care in design, and are more expensive than shed roofs. over However, they can be built large areas (buildings over 10 m. wide) without heavy beam or column support because they are made of relatively light materials and are extremely strong. Gable roofs are much less affected by wind than flat or shed roofs and are therefore better-suited to areas with strong storms. In addition, gable roofs provide excellent insulation against heat In areas with cold and cold. nights or seasons, the triangle formed by the double pitch above the ceiling helps hold the heat in In very hot areas, gable at night. roofs that are ventilated have the opposite effect: they pass heat out of the building quickly, thus helping to keep it cool. gable roofs are the In general, best, and most adaptable style whenever they are within,the builder's budget. HIPPED RtiFS Hipped roofs provide more protection auainst wind on the ends of a b&.lding than do gable roofs. But this is their only advantage Hipped over the other roof styles. roofs are harder to design, harder to construct and use more materials than any other roof style. Roof Materials Roof materials for the frame covering. fall into two categories: and those that and support, those that are used are used as the roof WOOD Wood is because material practical the most common material used for roof frames and supports When the covering it is strong and easy to work with. will be heavy (tile, for example), wood may be the onZy material for the frame and support of the roof. before planning to build a wood frame, or to use wood One caution: make sure th,at wood is available in beams for roof-support, Wood beams must be at least 5 x 15 sufficient quantity and size. cm., and wood used in frame construction should be at least 5 x 10 cm. To estimate the quantities of wood needed for any roof design, see pages 107-114 on roof construction plans. 105 BAMBOO Bamboo is an excellent frame especially where resistance material, to wind and earthquake are important It is light, flexible, concerns. and strong. Where large species of bamboo are available, they, zan be cut to make tiles for a roof covering. The chief are: disadvantages of bamboo nailed: a it cannot be easily most connections are made by tying section together with wire, or hemp lashings; thongs, . it tends to rot when exposed dampness or rain. to MUD Mud is the least expensive roof covering, disadvantages: it is very heavy; it tends cause leaks,and it requires very frequent collapse. but it has serious to develop cracks that repairs to prevent 106 TILE Tile roof coverings are also very heavy. The materials and labor involved make tile very expensive. Tile roofs should not be used in earthquake zones. REINFORCED CONCRETE This kind of roof is seldom needed If it is on small buildings. an engineer must be required, consulted on its design. CORRUGATEDMETAL OR ASBESTOS Corrugated iron, aluminum, zinc and asbestos sheets have several advantages as roof coverings: . they are . they are or gable . they are . they are . aluminum On the other disadvantages, roofs: very light; easy to use on shed roofs; usually leak-free; relatively fireproof; sheets are rust-free. hand, they especially have some on flat . they are cold in winter and hot in the summer; . they rust (except for asbestos and aluminum); . they are noisy during rain; . they tend to tear away easily during heavy storms or wind; . asbestos has been identified as a possible cause of cancer. THATCH Thatch is an effective and inexpensive covering for wood It is light. or bamboo frames. it provides better In addition, insulation against heat and it is However, thatch quieter than metal.. will not last as long as other roof especially in wet coverings, It is also easily climates. infested by animals and insects unless treated with an effective insecticide. Construction Details for Roofs FIAT ROOFS Flat roofs are built in three major steps: S!l’EP I: Placement of the beams across the width of the building: Wood beams should be about 5cm x 15cm. If bamboo is used beams should be made from the thickest stalks available. For heavy materials such as tile. place the beams at least every 0.6 -- l.Om. For lighter covering materials, the beams can be slightly further apart if desired. Each beam should be as long as the building is wide plus the length of overhang on both sides of the building. S!TEP2: Place purlins across the beams: Purlins are horizontal pieces of a roof frame that support either the roof covering material (in flat and shed roofs), or the pitched rafters (in a gabled or hipped roof). Each purlin should be as long as the building plus the length of overhang on both ends of the building. STEP 3: Cover the roof with the planned bolting, nailing, or lashing it covering securely material, tying, to the purlins. 108 SHED ROOFS Shed roofs can be built in two ways. Either wayr the beams for support can be both thinner and further apart than for flat roofs: . If one wall going the length of the building is higher than the shed roof can be the other, built with beam supports like flat roofs; . S I MPLE BEAM SUPPORTED SHED ROOF A much stronger shed roof can be built if the building walls are Beams are laid across level. Then pitched rafters the walls. made of 5 x 10 cm. wood planks are supported at an angle by Finally, the four struts. purlins are attached as in the flat roof and the covering material is tied to the purlins: TRUSS SUPPORTED SHED ROOF LO9 GABLE (DOUBLE-PITCHED) ROOFS Gable roofs are supported by light weight wood, bamboo, or steel structures called trusses. Basically trusses are triangular shapes strengthened by struts that help distribute the weight of the roof and the force of wind, rain, snow, and earthquake evenly. The illustrations on this page and the next show how trusses are used and identify their key parts. See the glossary on the next page for definitions of each part. GABLE ROOF: WITH PURLINS ATTACHED TO TRUSSES, AND USING END WALLS AS TRUSS SUPPORTS 110 GLOSSARY OF TERMS FOR GABLED‘ROOFS AND TRUSSES Abeam pladed horizontally across the width of the building and tied to the walls on each end. The cross tie is the bottom part of a truss-triangle. 2. Eczve: The part of a roof that overhangs the wall. 3. PurZh: Horizontal beams that tie the trusses together. (Not shown) 4. Rafter: Either of the angled parts of the truss. 5. RQfteP Batten: A short beam that joins the top of the rafters in a truss. 6. Rafter hzcketr A short beam that supports the rafter when there is a large overhang. 7. Ridge: The top point of the truss (also czlled the cqxx). 8. SpZke: A section in a rafter where two long pieces of wood are joined together with nails and a short piece of wood. 9. strut: Any short beam attached to the cross tie and rafters of the truss and used to provide strength. 10. mss : One of several triangular support-structures used to hold up a gabled roof. 11. WQZZ Phzte: The part of the wall to which the roof frame is attached. 1. Cross ITie: 111 Sample Truss Plans The following pages show the plans a gabled roof. The first plan (20-32 feet in buildings up to In either case, for two different is for roofs on buildings 6 to 9.6 meters wide U.S. measurements). The second plan is for 6 'meters wide (18 feet in U.S. measurements). the trusses should be placed 2 meters apart. The charts accompanying each plan indicate the part of the truss for any given building width. Note: trusses length of each The charts were originally prepared in U.S. measures. Field workers in areas using metric measures should try to find similar charts and plans in their local area, If metric since standard lengths may not be comparable. the charts printed here may be . charts are unavailable, used. for TRUSS PLAN FOR BUILDINGS BUILDING WIDTH, Meters 6 - 9.6 ESTIMATING LENGTH OF MEMBER, Meters METERS WIDE CONSTRUCTION Distance Between Bolt Connections C D A C W L 2A 6 6.0 3.75 4.38 2.32 1.25 2.10 1.83 2.11 1.05 6.6 4.05 4.72 2.52 1.35 2.30 2.00 2.31 1.15 7.2 4.35 5.05 2.75 1.45 2.50 2.16 2.51 1.25 7.8 4.65 5.40 2.95 1.55 2.70 2.34 2.71 1.35 8.4 4.95 5.80 3.15 1.65 2.90 2.52 2.91 1.45 5.25 6.10 3.35 1.75 3.10 2.69 3.11 1.55 5.55 6.45 3.55 1.85 3.30 2.87 3.31 1.65 9.6 6 113 114 I UP TO 6 METERS WIDE TRUSS PLAN FOR BUILDINGS 1 3/4" BOLT 6" Lona PURLINS ROSS 7-I C BOLT Long BOLT RING BEAM UUNU I.-. l5tHM 4" LONG 3” . . EUILhNG WIDTH, Meters ESTIMATING LENGTH OF MEMBER, Meters: i A IB‘. BOLT/M. S. ROD JhSTRUCT I ON Distance Between Bolg Connect ions I c I A B e 3.3 1.16 2.29 1.33 2.65 3.6, 4.35 1.30 2.85 4.2 4.95 ! 47: 3.20:. 4.5 4.8“ 5.55 ..:5 3 .,:i> 5. : I 1.51 2.99 6.15 f 52. s:90 5.7 1.67 3.35 I I \‘:,.. _::. .-. \ / 3 DlRECTlONS FOR CONSTRUCTION Once the construction plans construction can begin. for the entire building are complete, This section is designed to help the field worker and community member(s) organize their work to make the construction process and to provide step-by-step directions for the flow smoothly, critical parts of construction that are common to all buildings. The material is divided into six parts: . SETTING OUT (LAYING OUT) . FOUNDATION FOOTINGS . FOUNDATION WALLS . FLOORS . WALLS, WINDOWS, AND DOORS SETTING QUT ClAV!~G tX.JT) In order to begin digging the trenches required for a building's the builder must first foundation, transfer the lines and measurements indicated on his or her foundation That is, plan to the building site. the exact length, width, depth, and position of the foundation trenches must be marked on the ground. This movement from the plan to the actual site is called setting out. It is probably the most critical step in the entire construction process. FLOOR PLAN 117 A building accurately that will is set be: out o level: no part of the floor or foundation higher than another; THIS r---- l square: walls parallel same length; and the ~plumb: straight up and down, not leaning to one side or the other NOT THIS D THIS >THlS _____ -___---. 118 A building that is set out carelessly will be difficult or impossible to construct according the finished to plan. As a result, structure may be expensive to So it is maintain and unhealthful. important to take special care when setting out. There are three setting out: .Orientation the site; major steps of the building .MzrkGzg a simple outline building's foundation ground; l to on of the on the "batter boards" aromd the foundation outline and marking the position of inside walls, doors, and windows on the boards. PZacing TAPE MEASURE The tools shown on this page are needed to set out a building so that it will be level, square, and accurately measured. PLUMB BOB LEVEL BOARDS (5cm x 1Ocm x 1.5m) NAILS I- 119 Orientation The orientation of a building is the direction its front walls face: north, east, south, west or something in between. To mark the orientation on the site, This is easiest first find north. But if no compass with a compass. finding north is still is available, fairly simple. The builder should stand at the building position so that his/her right arm points at the spot where the sun rose in the morning while the left arm points to where the sun set the last night. In this position the builder will be facing north. SUNSET , 1 I Standing in the same position, if the builder moves his/her arms so they form a straight line to the sides, they will be pointing due west (left arm) and east (right arm). Once the main compass points have been established, use a stick to mark out the shape and position of the Add about 2 meters to the building. dimensions of the building on all sides: the extra space will be needed for supplies and work space during construction. i Next, clear the ground inside this area of trees, shrubs, and loose If the topsoil is plant growth. loose, clear away the top 15cm or so Y to get down to hard earth: loose soil will not support a building. the lan d at the positi If clearinq outlined proves too difficult, or if it would require felling trees that are desired for their shade or consider moving the building beauty, a short distance before clearing the land. PROXIMATE BUILD; 120 iMarking the Fsundatiosa Qutline The next step is to mark the outline of the foundation on the site using string and pegs. Three measures are very important: * the length of .each wall marked exactly: * the string * the corners 90° exactly must be must be exactly level; must be square: CORRECT of each wall is easy to set Simply measure out on level ground. it with a tape measure, making sure to pull the measure tight. The length INCORRE’;T : NOT ACCURATE J When the site is onwzevenground, care must be taken to measure the length of the wall along a level line: following the slope of the ground will throw off the measurements. 121 To prevent errors, begin at the highest end of the first wall's length and attach the string to a peg planted at the end-point. Set a new peg every 2 meters to prevent the string from sagging, and test to make sure the string is level by using a plumb bob and mason's square as shown: when the plumb bob stops swinging it will be plumb (straight will be up and down); the string exactly level when it is a 90° to the bob string. Repeat this process until the length of string set out is equal to the planned length of the first wall. 9 -----MB If the ground is sloped very steeply, it may be easier and more accurate to measure the wall's length in steps or stages. To do this run a new length of string from the bottom of every second peg (that is, every 4 meters). Test with a plumb bob to be sure that every peg is straight up and down. In addition, to be sure there are no gaps or .overlaps in the measurement of each new stager piant a small block with a circle on it right next to every other peg: then in measuring the next stage (or step) along the wall, hold the tape measure to the point in the circle that marks the end of the last stage. BOB Once the first wall has been set out the second wall should be set out at right angles to it (900). There are several ways to make sure that this angle, and the angles between all th walls set out are square: s A mason's square is good for distances up to 3 meters. Use it to get started, but don't use it to check the entire outline. . One of the easiest and most accurate methods of checking large distances for squareness is to compare the diagonals. Simply measure the diagonal lines from Opposite corners of the foundation When they are exactly equal in length, all the angles will be 90° On uneven ground, be sure to use the tape measure along a level line! . If measuring the diagonals is inconvenient, or if the building is not a simple rectangle, another method is the 3-4-5 calculation: If the wali on one side of a right angle is 3 units long and the wall on the other side is 4 units long, a-line drawn between their ends wit2 always be 5 units long. Here's how to use this rule to test whether the angle between two walls is square: Along the string set out for one wall, measure and mark off 1.5 meters (3 x .5m). Then, along the string set out for the second wall, measure and mark off 2 meters (4 x .5m). Next, measure and cut a piece of string 2.5 meters long (5 x .5m) and hold its ends to the Faints marked off along each wall. When the 2.5 meter string just touches both marks with no slack left over, the angle between the two wall strings will be exactly square. If the 2.5 meter string is too short or long, adjust either one of the wall strings Until it fits exactly. TRI ANGLE 123 :-KING THE INSIDE FOUNDATION LINES Once the outside walls of the .foundation have been set out with pegs and string, the next step is to set out a second set of lines to mark the inside of the foundation walls. Use the same procedures to keep them level, accurate in length, and square. The easiest way to begin is to measure the width of the foundation wall and mark it along the strings set out for two opposite walls. Then set out a string between these two points and fasten the ends with Use a plumb bob to be sure pegs. each peg is directly beneath the outside foundation line. Next, of the peg at lines corners Batter repeat this process for each remaining walls. Place a every point where the new cross: these are the inside of the foundation walls. Boards Batter boards are like a single rail fence placed around the building position. They should be placed after the foundation lines have been set out and before any digging for construction begins. Batter boards are essential for two reasons: . They provide permanent points for the position foundation walls: these needed once the string have been removed during construction; l reference of the will be markings They can be used to measure and mark off the exact position of doors, windows, and floors, thus making it much easier to build the walls accurately. To be useful, batter boards must be exactly and should be set about 1 meter back from the string marking the outside foundation line. le\rei 124 PLACING BATTER BOARDS To place batter boards around the building postion, first find the highest point on the site about 1 meter outside the outer foundation line and place a wooden stake firmly in the ground. Nail the first board to this stake so that the top of the board is at least as high as the top of the foundation walls will be. Since the foundation walls must be as high as the floor, this will be at least 20-30cm. above the ground. place a second stake 2 meters from the first and 1 meter outside the outer foundation line. When this stake is secure, nail the other end of the first batter board to it, taking care that the batter board is level. Nail a second board to this same stake and repeat the process of placing new stakes, levelling, and nailing the boards, until the batter boards form a fence that goes completely around the -building position. Next, AS THE PLANNED 125 HOW TO LEVEL BAT':,'? BOARDS A commercially made "spirit level" is the easiest levelling device to use. Place it on the surface - in this case the top edge of the batter board - and keep adjusting the height of the board at the opposite end until the bubble is in the center. When joining boards at stakes, place the level over the seam board to maintain a continuous line. of the level An additional check on level can be made at the corners: use an extra board to provide a surface for the level. Another method is to use a water level: this is a clear plastic hose that is filled with water. Adjust the first end of the hose to a known level mark. When the other end of the hose is placed at the next stake, the water inside will be at the same level as at the first end. To prevent spillage the ends may be plugged until the hose is in position. But all plugs must be removed to get an accurate measurement. SPIRIT LEVEL When Air Bubble is Between the Hair1 ines the Boards ar; Level \\ TRANSFERRING MARKS TO BATTER BOARDS Once the batter boards are complete, all the measurements shown on the written foundation plans should be marked on the boards. First, transfer the foundation lines marked by the strings set out earlier: run a strinq from one board to the opposite board directly over each foundation line. Use a plumb bob to make sure this new string is over the corner pegs. Next I place nails or saw cuts tops of the boards where they sect the strings. in the inter- A'good system is to use different marks for the foundation lines than those to be used for other important measures such as wall lines and the positions of doo::s and windows. For example, use small notches cut with a saw to indicate the foundation lines. Then use nails to indicate the wall lines. Once the foundation lines and *:lall lines have been marked on the batter boards, the builder is ready to start digging the foundation trenches. Note: the digging will be easier if the strings are left in place until the trenches have been well started. 127 CONSTRWCTIQN Digging the OF FOUNBATlON Foundation FOOTINGS Trench Before the concrete footing can be poured, the builder must dig a trench for it. The depth of the trench depends on characteristics of the site and building that should have been determined in the basic planning stage (see pages 82-88). However, the width of the trench, and the care with be dug depend on whether the concrete footing will directly in the trench or into wooden forms. which it must be poured TRENCHES FOR FOOTINGS POURED WITHOUT FORMS When wooden forms will not be used, the trenches must be dug very carefully: . the walls of the trench must be plumb (straight up and down); the earth forming the trench walls and bottom must be very firm so that there is no danger of the trench crumbling when the concrete is poured: l . the earth must be removed carefully so that the earth at the bottom of the trench is smooth, clear of all trash or debris, and undisturbed (undisturbed means that the earth has not been moved, loosened, or dislodged by the digging); ) . the bottom of the trench must be absolutely level: 6-8 measurements with a straight board and level should be made along the length of the trench to be certain of the level; 0 the trench must be exactly as wide as the concrete footing; . the trench must be free standing water. of UND I RI GHT 128 TRENCHES FOR FOOTINGS POURED WITH FORMS It is much more common to use wooden forms when pouring the concrete footing because the ground at building sites is rarely hard enough to stay in place when the concrete is poured directly in the trench. Like the trenches trenches footings, will be used must bottom, and hard. bottom must also clear of debris, for non-form in which forms be level at the The earth at the be left smooth, and undisturbed. However, there is no need to make the side walls of the trench plumb. The only requirement is that the trench be 30-45 centimeters wider than the footing will be, so that the:e will be room in the trench for the wooden forms and work space for the builders. A FINAL NOTE ON DIGGING TRENCHES When digging the trenches, any loose soil, or soil with organic material should be shovelled outstie the foundation lines and discarded. Hard earth that is dug up should be spread evenly &side the foundation lines: it will be very useful as part of the fill under the floor. Organic E Loose Soil 129 Formwork for Footings The formwork should be made of boards measuring about 5cm x 15cm or 5cm x 30cm. The boards should be supported by 5cm x lOcm braces called studs. Allow about twice the width of the footing between the studs (but never more than 1.3 - 1.6 meters); the formwork must be strong because concrete weighs 2.5 metric tons per cubic meter. Tight Joints to Prevent Leaks In addition: * e the joints and corners of the formwork must be tight: neither the concrete, nor the water should be able to leak out. If water leaks out it will weaken the mixture; the walls of the forms must be exactly plumb (straight down), and the tops of the forms must be level: any inaccuracies will weaken the foundation; up and . small boards, called spacers, should be nailed to the tops of the formwork to keep the sides of the forms from leaning toward each other before the concrete is poured; . the formwork should be built so that it may be removed easily without damage: most forms can be re-used; l if part of the footing will be visible and the builder would like its surface to be smooth, the boards of the formwork must also be smooth: .any irregularities in the wood - burrs, bends, chips, and so on - will leave an impression in the concrete, 130 FORMWORKFOR A STEPPED FOUNDATION The formwork for a stepped foundation is constructed in the same manner However, if the described above. walls will be made of block or brick, the height of each step of the footing must be equal to the height of the blocks used, or to a whole number multiple of their height. For example, if the blocks used in the foundation are 20cm high, then the steps must be 20cm or 40cm or 60cm high, and so on. Making the To prepare Concrete a strong, for Foundatisn durable Footings concrete . select, prepare, and store sand, gravel) properly; the mixture# ingredients . use proportions of these ingredients suitable for his or her purpose; l mix the ingredients water. properly the builder with that must: (cement, are each other and with SELECTING INGREDIENTS Cement The commercial cement most commonly used for l-story buildings is Portland cement. It is available from most manufacturers. Portland cement, and most locally made limestone cements, can be stored for up to 6 months in a cool, shaded,*, area. If the cement has hard lumps that are difficult to break or crumble, don:t use it. In humid tropical areas, or areas with heavy rainfall, it may be advisable to purchase "hydrophobic" cement, since this kind of cement can be stored in damp conditions for long periods of time. 131 Sand The sand is possibly the most important ingredient in the concrete mix, since it provides most of the plasticity: that is, it makes the mixture easy to work with. There should never be more than 3 parts sand for every 1 part cement. TOOZittZe sand in a mixture may result in shrinkage cracks when the concrete dries; too much sand will produce a harsh mortar that will be difficult to work with and may lead to leaks. Never use sand from the ocean: the grains in ocean sand are too uniform in size and will not make a useful concrete. Any other source of sand But it is crucial that the is fine. sand used be clean. To test whether to be -used: . put fill sand is clean 5cm of sand in a jar the jar with water: enough and WATER SAND b . shake the jar vigorously for 1 minute and let it stand for 1 hour. The layer of dirt that settles on top of the sand should be less than 6mm thick. If it is more, wash the sand or find other sand (but again, do not use ocean sand). SAND: SHOULD BE LESS THAN 6 mm THICK Gravel Gravel adds strength to concrete because it increases the range grain sixes in the mixture. Generally it is also the easiest ingredient to find and prepare locally. Gravel 247-201 should 0 - 71 - 10 be clean, and should range in size from 6-18mm. of 132 MIXING THE BEST PROPORTIONS OF INGREDIENTS The concrete mixture required for a foundation footing may be very different from the mixture needed for concrete used for another purpose. the average mixture for foundation For example, 1:2 3/4: 4 (that is, 1 part cement, 2 3/4 parts parts gravel). footings is sand, and 4 The higher But a typical mixture for fence posts is l:l:l&. proportions of sand and gravel in the footing mixture provide Since fence posts maximum strength and resistance to water. do not need to be as strong or as water resistant as footings, mixture. they can be made of a weaker and less expensive Table 4 in Appendix 5 recommends average mixtures for different Following these recommendations will assure uses of concrete. to their needs. builders that their concrete will be well-suited M3CXIBTG PROCEDURE Mixing Area Concrete should be mixed on a flat surface that will not absorb water. Mix it on a wooden platform about Or, mix it 2 meters by 2 meters. on a cement-sand platform. Cement-sand platforms must be made a week before concrete can be mixed on them. To build a platform, mix cement and sand on the ground in a 1:6 ratio, cement to 'sand. Add water, and spread the mixture in a circle about 2 meters in diameter. 133 Choosing A Measuring Unit Since the dry ingredients ‘of concrete, cement, sand, and gravel, are mixed by the easiest way to be sure volume, that the proportions are right is to decide on a standard measuring unit such as a box or wheelbarrow. Once the it to the ingredient make the foundation each unit of sand, unit is chosen, simply fill appropriate level with each in turn. For example, to recommended mix for footings, 1:2 3/4; 4, for of cement, add 2 3/4 units and 4 units of gravel. Generally, the easiest measuringunit to use is a gauge box or wheelbarrow that holds 1 bag of cement. The box or wheelbarrow should be approximately 40cm x 4(?cm x 40cm. Note: to avoid confusion, once the size of the measuring unit has been chosen, do not use different size boxes or wheelbarrows on the site for any purpose. When using a box: . the box should have handles on both sides for easy lifting by two people; . if the materials are close enough to the platform so that they do not have to be carried, it is easier to use a bottomless box: set the box directly on the mixing platform and fill it to measure; then, lift it up to empty the ingredients into the mixture. Mixing the Ingredients The ingredients always be mixed FIRST, spread in concrete should in the same order: the correct amount of sand on the platform with a shovel. GAUGEBOX 4 SECOND, dump the required amount of cement on the sand, and mix the sand and cement until the color of the pile is uniform: there should be no streaks of color. THIRD, add the required amount of gravel and mix it with the sand and cement until the gravel is thoroughly distributed and there are no streaks of color. FOURTH, hollow out a hole in the center of the.mix. Add water slowly, pushing the ingredients toward the center while turning them over with a shovel. 4 135 A good test of water is for the correct amount to walk on the mixture: a if you sink to your ankles or there is too much water; higher, a if you sink about 5-6cm, have the right mixture. you The correct amount of water is important because too much or too little will weaken the mixture: CORRECT AMOUNT OF WATER - if there is too little water, air spaces (weak spots) will form in the concrete; - if there is too much water: a cement-water paste will rise to weakening the the surface, mixture underneath. Pouring Concrete for Foundation Fresh concrete mix has carried to the footing water-tight containers wheelbarrows: no water seep out of the mixture: to be trench in such as should the mix sh.Duld be poured within 45 minutes-of mixing; l 0 l l Footings avoid b:;mps during transport from the mixing area to the site: vibration will cause the aggregates (sand and gravel) to separate from the mixture; it is flow drop sand best to let the mix into the trench; do not it into place or the and gravel may begin separating from the mixture; . once in place, a shovel, rod, the concrete should be worked up and down with or spading tool to break air pockets; . footings footings 30cm up to should deep can be poured all be poured in layers 15-30cm once started, the pouring must be continuous: has started to set crmnot be disturbed; at once; deeper deep at a time; concrete that if you must stop pouring at the end of a day, stop at the end of the poured section; place a vertical when pouring is resumed, roughen the edge of the old section and paint it with a cement-water paste before applying fresh (Use a stick or any sharp object to roughen the concrete. old section). l Curing Concrete Footings As concrete hardens, the water in the mix gradually evaporates. Prolonging that process increases the strength and watertightness of concrete. Immediately after the concrete has set , put a wet covering over The covering may be made with wet burlap bags, or a thin layer of wet sand, or uet straw. The covering should be sprinkled with water 2 or 3 times a day for at least 7 days. .I. Reinforced Footings Reinforced concrete footings require the same formwork as unreinforced footings (see page 129). Steel rods are attached to the form before pouring. The rods should be made of steel about 9mm in diameter. They must be cleat ---= free of rust. When placing the rods: . 'Jse steel wire to hold them in place 2.5-5cm above the bottom of the trench, and 5-7.5cm from the sides of the forms. Temporary wood supports may be used while the steel wire is being tied in place,' but they must be removed before pouring concrete. ' Plain (bars straight round bars must be hooked at the ends; deformed bars with curved ridqes along their surface) can be left since their ridges will hold the concrete firmly. . The ends of bars should be spliced (overlapped) for a the length at Zeast 30times diameter of the rods. For example, 9mm rods should overlap for 2.7 meters. e The rods must be complett_ly surrounded by concrete, and the concrete and steel must be fuZZy and tightly bonded to work properly; any exposed steel will rust through, and this will weaken the steel and destroy the bond. PLAIN ROUNP DAc “DEFORMED” BAR The recommended concrete footings is 1:2&:4. Footings section mixture may also be reinforced on Bamboo, page 188. CONSTFBUCTION OF THE for with reinforced bamboo. FOUNDATION foundation See the separate WALLS .Once the foundation footing.is complete, construction of the foundation walls can begin. The foundation walls may be made of concrete, or anyofthe blocks made with cement (Sand-Cement, Stabilized Earth). Adobe blocks should never be used for a foundation. The foundation walls should be built so that the top of the foundation is exactly level with the floor height (at least lo-30cm above the ground at the highest point on the building site). Concrete Fowndation Wafls MIXTURE The best concrete mixture for foundation proportions as the concrete for footings: walls has the 1:2 3/4 :4. same FORMWORX The best formwork to use for concrete foundation walls isre-usable unit formwork. Since each "unit" can be used over and over again, the cost of the wood for the formwork can be shared by an entire community. 139 ASPREADER! Typical form units . 2.5 meters are: long; . either 60cm or 120cm high, foundation ~311s; 4 made of boards l l supported about by braces depending 2.5cm x about bolted together, not nailed to assemble and disassemble. on the height of the 15cm; 5cm x 10cm; (Bolts make the units They also make the much easier forms tighter.). Before concrete is poured,the walls of each unit should be kept apart by 2.5cm x 1Ocm spreaders. Spreaders can be removed as the concrete is poured, since the concrete weighs enough to keep the forms apart. After the concrete is poured the walls of the unit-should be held together by 5cm x 1Ocm spacers. Spacers and spreaders should be placed at 1.5 meter intervals. POURING CONCRETE FOR FOUNDATION WALLS Concrete for for footings layers 15-30 walls before walls should time. foundation walls should be mixed just as the concrete (see pages 130-136).c It should then be poured in centimeters deep. Pour the first layer for a22 the going on to the second layer. All the foundation be built up together, rather than one wall at a it is best If possible, this one day's pouring: If it is surface it with surface. when the to complete all the foundation walls will avoid seams in the concrete. in necessary to stop before completion of the walls, the top of the last layer poured should be roughened by scratching a stick or placing large pebbles that project out of the This will provide a good "grip" for the fresh concrete pouring resumes. CURING In warm weather, the forms can be removed after 3 days; in cold weather, leave them on at least a week and preferably 10 days. As with footings, cover the surfaces of all concrete foundation walls for at least a week with wet sand, straw, or burlap. Block Founciation Construction Walls of a block a Making the blocks: . Laying the blocks; . Finishing Making foundation wall requires 3 basic steps: the Mortar. Blocks There are three types of block suitable for foundation walls: concrete blocks, sand-cement blocks, and stabilized earth blocks lnot adobe). Each-requires different procedures and ingredients. MAKING CONCRETE BLOCKS Ingredients The ingredients required for concrete blocks are cement, sand, and gravel in a 1:2:4 mix. The concrete is mixed using the method described on page .132-136. Forms The most commonnomina2 size of concrete blocks is 20cm x 20cm x 40cm. A 141 The nominal size of a block is the acttta2 size of the block + the thickness of mortar in which it will be set. Planning for 5mm cf mortar between blocks, this means the actual size of the most common concrete block is'19.5cm x 19.5cm x 39.5cm. Thus, the forms used for these blocks should measure 19.5cm x 19.5cm x 39.5cm on the inside. The forms should be made of wood 2.5cm thick, (or dowels) to create holes in the block. with removable cores Procedure The mixture should have enough water to make the mix plastic but not watery. The mix is placed in the form and hand-spaded or vibrated mechanically to remove air pockets. If the mix is spaded, the forms should 12 hours (or 2-3 days in cold weather). mechanically, the forms may be removed not be removed for at least If the mix is vibrated 30 seconds after vibration. The cores should be removed first: tap them gently out slowly. Then slowly remove the outside form. the corners and edges. and pull them Avoid breaking The blocks should be kept damp for 7-10 days and should sheltered from wind and sun for 28 days before use. be MAKING SAND-CEMENT BLOCKS Inaredients The usual mixture of cement-to-sand 'for sand-cement blocks is 1:6. A mixture of 1:8 can be used for block walls that will not carry roof loads, but this is not sufficient for foundation walls. The best sand is clean river-bed sand composed of many different size particles. If it is dirty, the sand should be washed, or sifted through a fine screen (4-5mm square), since dirt will weaken the blocks. Do not use ocean sand. M_ixing Site The site for making sand-cement blocks should be flat and shaded: if the blocks rest on an une-ven surface, they will crack before they harden; and direct sun will dry blocks out before they can cure properly. If the mixing site mustbe in the open sun, the blocks should be moved to a flat, shaded area for curing. 142 Mixing Following the mixing procedure for concrete (page 132), measure out the proportion of sand and then mix the cement in thoroughly. AddcZearlwater in the center of the pile and turn the ingredients over at least 3 times until all streaks disappear and the mixture is even. The mix should have the consistency of concrete: wet, but not watery. Moldina Sand-Cement Blocks Sand-cement blocks may be molded by hand or with a simple hand-press. Blocks made by press are generally stronger and more durable. But blocks made by either method are acceptable. Hand Molding. If a commercially made mold 1s not available, a mold? can be made out of 2.5-5cm lumber in the dimensions desired. Typically, these blocks are: ACTUAL SIZE, cm 19.5 x 19.5 14.5 x 19.5 9.5 x 19.5 x 39.5 x 29.5 x 29.5 NObUNALSIZE, cm 20 x 20 x 40 15 x 20 x 30 10 x 20 x 30 Once the molds of the correct size have been built, shovel the wet mixture into the mold and shake the mold to settle the contents. Then re-fill the the top and pack with a spade or excess off after mold slightly over the mixture down shovel. Scrape any packing thoroughly. 143 Next, carry the full mold to the curing Turn it upside down gently, from any previous blocks. Then, lift the mold off: and place first area. it a few centimeters away the core; then, the casing. Repeat the process until enough blocks have been made. Using several molds simultaneously will greatly speed the process. 144 There Molding With A Hand Press. are several types of has press available for making strong sandCinva-Ram and cement blocks. Tek-Block presses are the most press will common, but any similar work as well. There are three basic steps in the operation of most hand presses: 0 loading the mold box; . compressing l ejecting the mix; the block. With any hand press, it is a good idea to make a few test blocks before starting production in order to determine the correct amount of mix needed to make a strong block. i45 Curing D Sand-Cement Blocks with water after they have Sii. --cement blocks should be sprinkled They should be dampened at least once a set for about 12 hours. They should not be laid up in a wall for at least day for 5 days. 12 days after being molded. MAKING STABITIZED Ingredients EARTH BLOCKS and Soil Selection The selection of a suitable soil for mixture with cement is crucial in making strong stabilized earth blocks. There are, roughly, 5 kinds of soil: - rock ranging from 5mm gravel to 7.5cm; - rock particles 5mm and l sand smaller; - very finely ground rock, l silt spongy when wet, but not sticky: - very fine grained earth, l czQy sticky when wet, hard when dry; - spongy, stringy a orgcmic soils appearance, odor of decaying, wet wood. . The best natural soil for stabilized earth blocks is sandy clay. As with plain concrete, ,the strongest blocks have a combination of fine, medium, and coarse particles. Earth that has only one particle size, or has mostly organic and/or coarse particles is unacceptable. STABILIZED EARTH B;OCK FORM 146 Testing Soil Acceptability To determine whether local soil can used to make stabilized earth use the following test, blocks, called the "jar test": be Fill a glass jar about l/3 full of soil. . Add water to the 2/3 mark. Shake vigorously for 11.minute. : Let the jar set for an hour. When the soil has settled there should be 3-4 distinct layers in the jar. If there are not, reject the soil. l Deciding /VEGETABLE HATTER A VERY FINE 1 FINE v COARSE How Much Cement to Mix With Once an acceptable soil much cement to mix with This can be done easily the Soil has been found, you need to determine how it to make strong stabilized earth blocks. with a "shrinkage test": Make a box 4cm deep, 4cm wide, and 6Ocm long. Grease or oil the insides thoroughly. Fill the box with damp, but not muddy, soil. Pack the soil with a shovel. or spade, especially at the corners. Level the surface with a str,aight edge or ruler. Place the box in the sun for 3 days, or in the shade for 7 days, and protect it from rain, The soil should shrink .and develop 3 or 4 cracks. IT 6 o~more cracks appear, or Zf the dried sdZ arches out of the box, reject the soil. It will not make good blocks. As long as there are less than 6 cracks and the soil lies flat in the box, measure the shrinkage .by tapping the box and sliding the soil to one .end: If the shrinkage lcm or less lcm to 2cm 2cm to 4cm 4cm to 5cm more than 5cm is: use a cement: ratio of: soi 1 - l-15 1-12 l-10 I- 9 reject the soil, or add sand and repeat the test 147 Mixing the Ingredients Once a sui table soil has been it should be screened selected, through a wire mesh with holes no larger than 5mm. After the soil has been screened, measure out the proportions of earth, cement, and any sand to be added. On a platform or other flat area, mix the ingredients thoroughly as for concrete. Add water slowly with can until the mixture not muddy. To test correct handful B l l l a watering is moist but whether you have added the amount of water, squeeze a of the wet mix into a ball: If it can be broken in two without crumbling and without leaving moisture in the hand, the amount of water is correct; If the mixture crumbles, too dry. Add more water repeat the test. it is and If the mixture leaves moisture in your hand, it is too wet. Compress the mixture and allow the excess water to run off. It is best to test the mixture frequently to avoid getting it too wet. n _-. - 148 Curing Stabilized Earth Blocks The moisture in stabilized earth blocks should be eliminated from sun and rain. under cover, with the blocks protected slowly, For the first 3-4 days the blocks should be separated in single They should be sprinkled rows, never stacked upon each other. After 4 lightly with water twice a day for this initial period. may be stacked up to 10 layers high in a pyramid the blocks days r On the 8th day, fashion with a little space between each brick. bricks may be laid up in a wall where they will continue to cure and gain full strength in about 30 days. laying Block Foundations When the footing has been poured and has cured for about a week, and the blocks have been made, construction of the foundation wall can begin. All block foundation walls, whether or stabilized sand-cement, concrete, are laid the same way. earth, SECOND COURSE stack a number of blocks at First, line so along each wall intervals that a szqply is always at hand. FI RST COURSE Next, lay out the planned number of blocks for the first row (course) on or alongside the footing and check to see'how well they fit the length of Very small adjustments in the wall. the length of a wall (under 7.5cm over the length of the whole wall) may be made by increasing the size of mortar joints between every 5th or For example, if 8 joints 6th block. are made lcm instead'of &cm, the wall length will be increased 4cm without cutting any blocks. To give the wall strength, the courses (rows of blocks) must be staggered so that the bond between any two blocks rests over the middle of the block beneath them. To stagger the courses, turn one corner block on the first course so Then, on the its "head" faces out. turn the block at the next course, opposite corner head out. Continue alternating between courses in this way. I STAGGERED BOND I 149 To ensure that the blocks are laid in a straight line, run a string from corner to corner along each For outside walls, attach the wall. string to the batter boards; for attach it to a nail inside walls, hammered between two courses of blocks. [ If the string sags, as it is likely to do over a distance, support it with a piece of paper that is weighted with a small rock. Use the string as a guide, laying each block up to but not touching thz The string can be moved up line. later for each new course of blocks. Once the string is in place first course, you are ready prepare the mortar. for to BATT,,, BOARDSL 1 PAPER WEI GHTE0”;; the The recommended mix for mortar to lay blccks is 1:3, 1 part cement to 3 parts sand. Mix these ingredients with each other and with water as concrete is mixed (see page 132). During the dry season, it helps to sprinkle the blocks with water before they are laid in mortar. This prevents them from absorbing too much water from the mortar. To lay the first course of blocks, use a trowel to spread out a full bed of mortar about 1.25cm thick on the footing. To prevent the mortar from drying out before blocks are laid in it, spread only enough for 4 or 5 blocks at a time. Using the batter board lines as guides, position the first block the corner block - very carefuZZy: an error here will cause problems that are hard to correct. When the corner block is positioned., tap it down firmly - do not pound until it is solidly bedded in the mortar. STRiNG w-c..-.zj -:-t .. F 150 Butter the ends of each new block to bond the vertical joints Press each new between blocks. block against the previous one until a solid mortar joint about 15cm wide is formed. Keep trowelling minimum: it will the mortar mix, of the bed to a draw water out of weakening the bonds. Any excess mortar that squeezes out between blocks should be scraped off. It can be re-used if it has not dried Once mortar dries out it must out. be discarded. CHECKING LEVEL After every 3 or 4 blocks are laid, if check the course with a level. remove the blocks. it is not level, and lay them again. add mortar, Once the entire first course of blocks is down, build up the corners at least 4 or 5 courses up, or all This will give the way to the top. you something to attach the guide string to for the upper courses. STORY POLE Bw Use a story pole to check the height and to check that of each course, all corners are going up evenly. FIRST 152 FINISHING THE MORTAR After the mortar has set, but before it has begun to harden, use a bent round bar called a "jointer'! to "tool " each joint: run the bar along each horizontal joint, pressing against the mortar firmly. This action will seal the joints, help weatherproof the mortar, and improve the appearance of the foundation wall. Cure the mortar by sprinkling the wall with water or brushing water on with a broom once a day for 2 or 3 days. Rock Foundation Walls Rock footings and foundations consist of two parts: a concrete base 5-7.5cm thick, and a rock-andmortar wall. The procedure for laying both the base and the wall is nearly the same as the procedure for concrete footings and block walls. The bottom 7.5-10 centimeters of the trench will serve as the formwork for the concrete base, so the sides and bottom of the trench should be clear and level. As with any concrete footing, care should be taken not to disturb the earth on the bottom of the trench. FIRST, dig the trenches. SECOND, gather the rocks. This can be done while the trenches are being dug. The rocks should be 20-40cm long on average. Larger rocks tend to be better because they will use up less mortari The rocks must be clean, so use water and/or a stiff brush to remove all crusted dirt from their surfaces. 152 Use the procedure for pouring concrete footings without forms as a guide for this step (pages 127 and mix of 1:2 3/4 :4. Let the concrete cure 1351. Use a concrete for 2 to 3 days. THIRD, pour the concrete. Tie a string to the for laying the rocks. Use a mortar mix parts sand. Spread a mortar bed about the concrete base. Bosition the rocks as if they were blocks. FOURTH, Zuy the rocks. Mortar all the joints between the rocks; the outside surfaces of the walls don't have to be flush, but the joints should be compact. . Be certain to lap all the joints (that is, stagger the rocks) to prevent a straight-line crack from developing. If possible, alternate the direction of the "corner" rocks. Finish the exterior mortar joints in the wall with a jointer to strengthen the joints and help waterproof the mortar. . Keep the top surface of the rock foundation wall as level as possible. batter boards as a guide of 1 part cement to 3 1.25-2.0cm thick on top of and tap them into place 153 CONSTRiJCTION r OF FLOORS After the foundation walls are complete, regular walls, a floor should be started, the foundation walls. Earth but before starting the level with the top of Floors Earth floors are easy to build. For drainage, simply place a layer of dry fill inside the area bounded by the foundation. The fill can be made of any material that will not hold water, such as gravel, rock, broken brick, or rubble. The top of the dry fill layer should be about 5cm below the top of the foundation walls. The fill will be packed down as people walk over it during the rest of the construction process. When the walls are complete, add a lo-15cm deep layer of hard earth and pack it down either with a shovel, or by walking on it. When the hard earth is well-packed', wet it down slightly, and sweep it out to complete the floor., )HARD PACKED EARTH Foundation Wall) _- Concrete Floors FILL concrete floors need a level of dry fill Like earth floorsp Dump the underneath for protection against ground moisture. fill inside the foundation walls so that it will be packed down by rain and people walking over it during construction The fill should be composed of two layers: of the walls. broken brick, or rock, gravel, a bottom layer of dry fill: If dampness in the area and a top layer of hard earth. rubble; is excessive, a 5-7 cm. layer of sand with a sheet of plastic (or other waterproof material on top) should be laid between the dry fill and hard earth. a CONCRETE PACKED EARTH f / Ilf The top of the hard earth of the foundation walls. SAND (DPTHINAL) should be about 10 cm. below the top PREPARING TO POUR THE CONCRETE Concrete floors can be poured at two stages process: after the foundation wails are complete, l are put up; after the walls have been put up. l in the but construction before the walls There is an advantage to the second alternative: since the floor and walls will very likely settle at different rates, the floor Another may develop cracks if it is connected to the walls. advantage is that the walls and doors provide easy protection for the floor while it is curing. if the fill has been in place some time, check that the hard ear,th is at the correct level--about 10 cm. below the top of the foundation walls. If it has settled, add more hard earth and pack it down hard. Wet it and then pound it with the end of a steel rod. Use a straight edge and a level. to check that the surface is reasonably level before the concrete is poured. Pound 6 or 8 wood stakes (about 5 x 10 cm.) into the fill so that their tops will be even with the level of the finished floor (the same as the top of the foundation walls). These stakes will guide you during the pouring, but they must be removed before the concrete settles. POURING THE CONCRETE The best concrete mixture for floors cement:24 parts sand:3 parts gravel). described on pages 132-135. is a 1:29:3 mixture (1 part Mix the cement as frbm where you will finish Then, begin pouring in the corner farthest and work back toward a door so you can get out without walking on the fresh concrete. Pour the concrete at the full thickness-10 cm --don't layer it. 156 As the area covered grows, begin to level the concrete off with a a board about 5 x 10 cm "screed"-and several feet long that is swept across the surface to keep the mix even with the tops of the guide-stakes. Then, before the concrete 1. remove the guide-stakes fill their holes with sets: and concrete, 2. tap any pieces of gravel and rock that stick out above the surface into the concrete and smooth the surface over. Using thin boards to kneel on or walk across the surface without .. marring the fresh concrete, "finish" the floor by sweeping a trowel or wooden "float" across A rectangular the surface. float is best--approximately .15 x -25 cm. The sweeping action will bring a smooth cement-water paste to the surface of the floor. Be careful not to bring up too much if water collects in small water: pools, the surface of the concrete will be too weak when dry. After the floor has started to harden, but while it is still sweep the surface with workable, This will give a rough a broom. texture to the finished floor and surface. create a safe, non-slip, When the floor is finished and is left to cure, close the, doors and windows to keep children and animals from walking on the surface. The floor should cure for at least Keep the 4 days, and preferably 10. surface moist by sprinkling frequently. Since so much area is exposed, the concrete can easily dry out too quickly. 157 CONSTRUCTION M!!MDOWS-a.m., AND OF WALLS, DOORS construction of the walls, Once the foundation walls are complete, This part of the manual covers windows, and doors can begin. two kinds of wall construction: - Block or Brick Walls, - Rammed Earth Walls. BLOCK AND Making the BRICK Blocks and WALLS or Bricks BLOCKS WITH CEMENT CONTENT The procedure for making concrete, sand-cement, and stabilized earth blocks is discussed earlier on pages 140-148. For walls made of these materials, build a mold for blocks f the length of a the f-length bloc.ks will make the framing full-size block: of windows and doors considerably easier (see below). ADOBE BRICKS Adobe bricks are made from clay and sand. (very fine particle material) will increase sizes and strengthen the mixture. The proportions a good mixture Adding straw of these materials can vary to begin with would include: 0 6 parts sand, 0 24 parts clay, 13 parts silt. l or chopped grass will always Where available, silt the range of particle considerably. strengthen But the bricks. Make some test bricks and then adjust the proportions as necessary. Some things to keep in mind while experimenting with different proportions: - silt should never be more than 15% of the mixture; - A healthy amount of sand is necessary to keep the clay from shrinking. On the other hand, too much sand makes the mixture watery and weakens the bricks as they dry. 158 Mixing Materials. Use a mixing platform as for mortar or concrete (page 132). Measure out and mix the proportions and add water slowly: if the mud is too wet it will slump gradually while it dries outside No large stones or lumps can be left in the mixture, the mold. but stones up to 1.5 cm are all right. Molds. The most common adobe brick it is made with a bottomless 9 x 14 x 29 cm. has anom&zuZ size of 10 x 15 x 30 cm. mold with amha2 inside dimensions of Use hard wood for the mold.* It may be easier, of sheet metal. to line the mold with a strip bricks at a time are easy to make and increase brick production. Like blocks with cement content, adobe bricks cannot be broken neatly into halves or quarters. So, for framing windows and door jambs, it's best to make a half-length mold as well as several regular molds (see window framing below, page 162). after some experience, -__ Molds for several the efficiency of 390; Png Adobe Bricks. Bricks can be made on flat, often faster and easier. Place table. Fill like a clean it with mortar, mold level (dipped ground, in water) but using near the a table is edge of the mlud, being sure to pack the corners. should be workable but not sloppy. The mud, Clear any excess mud off the mold, but don't make the surface too smooth-- the brick will adhere to the mortar better if it has a rough contour, Slide the mold briskly off the edge of the table it in a vertical position to the drying site. I WATER BARREL I I Gently place the mold on close to the JC?m$ ground, last brick made. Let it sit for a few moments, then lift the mold up slowly. Rinse the mold off thoroughly (in a barrel of water) before making another brick with it. D and carry 160 Curing Bricks must be dry before they can be used; if they dry in the wall they will shrink and ruin the mortar bonds. The bricks should dry in the sun for about 30 days. For the first week or should be protected from rain. Sheet metal SOf the bricks provides a good protective cover. After the first week they can be safely exposed to light rainfall. Turn each brick over every 5 or 6 days to assure even drying. A Note on Mortar Adobe bricks are generally mix as the bricks. Laying Blocks and laid with mortar made from thesame Bricks The basic laying procedure for block and brick walls is the same for all types of block and brick and is identical to the procedure for .block foundation walls (see pages 148-151). 0 The top surface of the foundation, or of the previous course, should be covered with a bed of mortar. Apply the mortar only on the edges of hollow bricks. Cover the entire surface of solid blocks. . Butter each new block or brick on its ends either before or after it is placed. Again, butter only the edges of hollow blocks; butter the entire head of solid blocks. ‘ORE 161 . Use string to guide the placement of each new block or L brick in a straight line. BUT NOT Position the blocks or bricks TOUCHINup to but not touchhg the string. Press and tape each one firmly into place so that the mortar joint is l-1.25cm thick. Do not pound the block in place. a - zz:z:? @.&j .pyf :-'::;:.:, .., ::: After every 2-3 blocks or bricks &~~ .a:::.+:.. check the course for level and plumb. Remove and re-mortar any blocks that are out of iine. -.-.._.... .......&..~.~.-.L.: .............>...'..... :::z ..,.,.., .......:,. ...:::.::,::..-.'...:..~..-..,..~~... HOND ARRANGEMENTSFOR BLOCK AND BRICK WALLS There are important differences between the bonds that used with blocks and the bonds for adobe bricks. Bonds for BLOCKS With should be Cement Content The main bond for blocks with cement arrangement used in block foundation easily continued through corners by each corner block ( see page 148 for When working with blocks, intersection of exterior interior walls is treated much like a corner. the and content is the staggered walls. This simple bond is alternating the direction of details). I i I 162 When framing windows and doors, the blocks next to the opening must be half-size in every other course: hence the great advantage of using a half-size mold. Bonds for l3ricks In any given course, adobe bricks can be laid so that they are stretchers (that is, placed end-toor headers (placed side-toend), side). Thecomers of brick walls should be built up just as they are for block walls, using stretchers and alternating the direction of corner bricks. But after different length of used most the corners are built up, bonds may be used for the the walls. The bonds frequently -are: . for bricks with a cement content, headers for the first course and then every 6th course I with stretchers in between; 163 . for adobe bricks, the first course 4th course, with between. headers for and then every stretchers in Headers should never come closer than 60cm to corners. Walls shorter than 2 meters (for example porch walls and half walls) should not have When beginning a headers at all. course of headers, start with a & brick: otherwise the bonds over the rest of the wall will not be properly staggered. Double Brick i$ BRICK TO ST/ fiT 8111LD UP CORNER FIRST AS FOR BLOCKS Walls Bricks used in exterior walls may have to be doubled to provide adequate thickness. Double brick walls are laid with alternate courses of headers and stretchers, beginning with stretchers. The illustrations below show how to handle (a) the length of the (b) corners, and (c) the intersection of exterior and walls, interior walls. (a) STRETCHERS PAI RED EXTERIOR WALL 164 Framing Windows and Boors Windows and doors in block and brick walls must be planned so their heights are coordinated with the size of the block or brick used (see pages 95-96). All windows and doors consist of 3 basic parts: the head, the and the jamb. In addition, there must be a lintel above the sill, opening to support the blocks or bricks over the open space. FRAMING WINDOWSAND DOORS IN BLOCK WALLS In of be the block walls, the lintels should be made There sh,-Td ----a- also reinforced concrete.. a concrete sill about 7cm thick under wood s.ill of the frame. Frames (heads, jambs, and sills) should be wood, usually 2.5cm x 15cm hardwood lumber in block walls. To build the a block wall, space for a window or door follow these steps: in JAM6 WOOI ... e? I. 9: Lintel 1. Make a mold for the reinforced The mold should concrete lintel. be as wide as the wall, as deep as the height of 1 block, and 13 times as long as the window or door is wide. 2. Fix 2 reinforcement rods in the mold and pour a 1:2:4 concrete Remove the mold and cure mixture. the lintel as you would a concrete footing (see page 136). FRAME FOR LINTEL CONCRETE SILL 165 b The Sill 3. Make a mold for the concrete sill. The mold should be as wide as the wall, about 7cm deep, and as long as the window Then, pour a 1:2:4 or door is wide. concrete mixture and cure it just as the lintel was cured. 4. Prepare the surface of the wall the sill will be placed by spreading of mortar on the blocks. where a bed 5. Put the sill in place and press it down firmly until the mortar joint is the same thickness as the joints between courses. 6. Immediately check for level and adjust, by forcing one end down. If if necessary, the sill is not level after this, take it add mortar, and repeat. off, TEMPORARY BRACE 1 The Frame B (2.5cm x 15cm hardwood) 7. Place the wooden frame sill and hold it in position temporary braces. on the with concrete 8. Continue laying blocks on either side of the window: the wall must go up evenly on both sides or it will qo out of plumb. 9. Attach the frame mortar and with nails masonry. to the wall with hammered into the 10. At the top of the opening, pre-cast lintel like a block: l l lay the if the walls are more than 75cm thick, allow a few hours for the courses below to harden before placing the lintel: apply mortar to the blocks or bricks at both ends of the lintel and adjust for the same joint thickness; . check for level and adjust. FRAMING WINDOWSAND DOORS IN ADOBE BRICK WALLS Adobe brick walls require wood lintels and sills that serve as the head and base of the frame. The easiest method is to make the lintel and sill equal to the height of the brick used (usually 10cm) so you do not have to cut or make bricks in half-heights. When the wall reaches or at floor level for the frame in position mortar and support it The jambs of the frame thick.. Check for -T- MULL I ON > window height a door - place on a bed of with braces. should be 5cm level. Lay the next course or two of bricks At this point, the wall and check again for level and plumb. _ . on each side of the frame will exert enough pressure to keep it in position. support the lintel with a Before laying bricks over the lintel, The temporary 5cm x 1Ocm or 1Ocm x 1Ocm post, called a mullion. mulIion should remain in place until construction of the wall is complete, Roof Preparation Near the top of the wall, attaching, and providing preparations support for, must be made for the roof. There are two basic kinds of preparation: wall plates and ring beams. They are built and used in the same way on all block and brick walls. 167 WALL PLATES Wall plates are solid, continuous wood beams (usually 5cm x 15cmj that connect the exterior walls of a building along their tops and anchor the roof to the walls. They are essential in all buildings except bamboo structures. The wall plate can be held place with 3 devices: in a a good mortar bed; as thick as the horizontal joints in the rest of the structure: . steel straps (bale iron wire) anchored l-3 courses below the top of the wall (at least 20cm); place the straps in the appropriate mortar joint every 3-l meter; b BALE IRON . bolts anchored l-2 blocks or bricks below the top of the wall every 2 meters: -with small bricks, the bolts can be anchored with a thin metal plate (called a retainer plate) between mortar joints; the bolts can be placed -with hollow blocks of whatever size, in a core and the core filled with concrete (1:2:4 mix). Corner joints joints of the wall or batten joints. plate may be fastened Battens are slightly BATTEN JOINT WITH BALE IRON STRAPS either with stronger. lap LAP JOINT WITH BOLTS RING BEAMS (ALSO CALLED THE BEAMS) A ring beam is a continuous reinforced concrete beam poured in place at the top of concrate block l&.ztts only. Ring beams help the walls resist the outward-spreading pressure from the roof, provide extra reinforcement in earthquake areas, and provide a solid base on which to attach the wall plate. 4 RCEMENT RODS ST COURSE OF %L.OCK REINFORCEMENT BARS 4 169 Ring beams are poured in place, so formwork must be attached to the sides of the walls already up. The beam should be about 15cm deep and exactly as wide as the wall. It should also be reinforced with 2 steel rods l-l&cm in diameter. Follow the guidelines formwork on page.129 1:2:4 mixture. To avoid for concrete and use a any seams, ring beams must one continuous operation. be poured in RAMMED EARTH WALLS Rammed earth walls are built in layers by packing a damp earth mixture into temporary forms, allowing each layer to dry slightly, and then moving the forms to repeat the process until the walls are as lligh as planned-.. Earth Mix-ture The earth used should be basically the same mixture used for adobe However, the proportions bricks (page 157). of ingredients are not critical. Large amounts of straw added to the mixture will increase the strength of rammed earth walls significantly. Only a little and damp (not If water should muddy). be added to theearth until it is firm a suitable grade of earth can be found, properly damp (after season), it can be brought directly to the building site used as-is, or with straw added. rainy the and ES Forms . I RON STRAP The most manageable size for the forms is 45cm deep by 2 meters long and 37~.5-45cm wide, depending on the wall thickness planned. III FLAT I RON BAR (TO StjPPORT MOLD) The forms should be closed on 3 sides: the open side is placed against the previous section of wall. There can't be any inside the spreaders or supports comes form, so the form's strength from battens on the outside held in place with iron straps at the top and flat iron bars at the bottom. Two special forms should be built for corner sections with alternate long and short sides. The se "corner" forms are held together with interlocking iron pins in addition to the strapped battens. L LONG SIDE 25ciii A - : RDN P-ii Rammed earth is not very easy to mold or shape once in place, so planning beforehand is essential. First, mount the forwork on the foundation wall, using-iron straps or wire around the battens. Check the form for level and plumb. CORNER FORi4 DETAIL - Place 1Ocm of earth in the form and pack it down solidly with a small rod about 4cm in diameter. Use quick, short strokes. The corners must be especially wellpacked. As much as possible, avoid shaking or vibrating the wall since this tends to loosen the earth. Add more earth and ram it down until there is a firmly packed layer 30cm deep. Scrape lines about $cm deep in the top suzfacs to give the section some additional "grip". 4 171 REVERSE MOLD FOR EACH COURSE Wait at least an hour before removing the form and starting new section above the first. a If the earth on top of an old layer it lightly has become dry, sprinkle to dampen it before putting new earth on top of it. Overlap the corners by alternating This will short and long legs. greatly increase the strength of the walls. Rammed earth walls can be Run a steel band reinforced. around the entire building just Rbove the door and window level. A second band can be run just below the roof if desired. CE To guide the steel band around drive pegs about 20cm corners, long into the rammed earth before removing the form. Framing Windows and IN FORCEMENT Doors Windows and doors are framed according to the same basic procedure followed with adobe brick Use walls (see pages 164-165). wooden sills and lintels about 5cm thick. place the sill r'irst, top of the damp earth. in the proper place Check for level. Wext, place the frame, including the sill, and brace it. Then place up on both forms on either checking sides, Finally, before building temporary brace. and press the combination it into the head-lintel on side of the frame and build the walls the frame frequently for plumb. above the lintel, support iz. with a 172 Roof Preparation To mount a wood wall plate on the top of a rammed earth wall, place steel rods in the wall about 3-l meter below the top of the Then wrap iron straps wall. around the wall plate and fasten both ends of each strap to the steel rods. CONSTRUCTION OF ROOFS It is a good idea to coat all an anti-termite solution-such In areas with very have an experienced Flat strong local wood and bamboo roof materials with as carbonyl, .. Xylophene, or Creosote. winds or storms, it may be advisable contractor check the roof plan. Roofs To build a flat roof, the steps below: l WA1 simply follow Place the beams across the top of the walls every f-l meter and lash them securely to the wallplate with iron straps or staples. Avoid nails through the beams since they may split the wood. to . on the ground, construct the purlins out of sections of 5cm x 1Ocm Purlin sections wood. should be spliced as shown, wtth together, the Zonger piece over the shorter piece. Take care CORRECT: Long piece piece is suppvrted by the short that splices will not be directly over a beam once the purlin is in Each completed place. purlin should be lifted into place and lashed witn iron straps to each beam. 0 Shed the roof Finally, covering should be attached to the purlins. Follow local custom when using materials such as thatch, mud, or tile. Avoid corrugated metal for flat roofs: the metal sheets make buildings very uncomfortable in hot climates and tend to rip off easily in wind. INCORRECT: Nails are not strong enough support the long piece Roofs Simple, beam-supported shed roofs for buildings where one wall is built higher than the other-are constructed according to the same procedure for flat roofs. One Wall is Higher to 174 For truss-supported follow these steps: shed roofs, STEP 1. Place beams across the top of the walls as for flat roofs. However, these beams may be further apart, up to 1.3-i.4 depending on the roof meters, covering to be used (closer for heavier materials, further for The beams lighter materials). must be as long as the distance between the two walls they will rest on + the overhang planned on each side. STEP 2. On the ground, and -mark off the outline truss. measure of the P m---i -=- ---0 ------r,-- ---l4 -;I-0 ------I fiil 1 I STEP 4. Fasten the pieces the truss together, either bolting or nailing them. of by Whether bolts or nails are used the -joints may be as fasteners, made either by overlapping pieces; or, by using single or double plates (separate pieces of wood) to hold the truss members together; err When splicing, use by splicing. iron straps to reinforce the joint fur-ther. b 176 STEP 5. Repeat steps beam in the roof. 3 and 4 until the trusses STEP 6. To position follow the instructions material, Gable a truss has been built and attach purlins for gable roofs for each and roof below. 4 Roofs To construct a gable roof, follow the steps below: STEP 1. With a tape measure, mark off the outline of the truss -- the di-stance from the rafters to the tie beam, from the struts to the tie beam, and so on -- on Loosely organize the the ground. pieces for the first .truss along the lines marked and hammer stakes in the ground to hold each member in place. STEP 2. Check the measurements of the pieces on the ground 'against the plans and make any needed adjustments; then make sure the stakes are firmly in the ground and won't move. 4 STEP 3. Assemble the truss with permanent connections as for shed roof trusses using theconnections indicated on page 175. STEP 4. As each truss is assembled, put it up by pushing over the wallmt, and then raising the point of the truss with a long pole. it TEMPORARY PURLINS first, STEP 5. Put the end trusses Then bracing them from the ground. run a string from apex to apex and align the other trusses with the string. TRUSS /i. J/N ,LS AS TRUSS SUPPORTS in place STEP 6. Hold the trusses with temporary purlins nailed to down each one'. Then tie the rafters to the wall plate with bolts or iron straps. I RON the STEP 7. Next, construct purlins on the ground, rather Stagger the than on the roof. joints in the purlins to avoid sagging in one section of the roof. Be sure that no joints are placed directly over a truss beam: too many nails will split the l-umber of the truss. STEP 8. Attach the purlins to the trusses, starting 20cm from the top of each one. The position of each purlin should be marked in advance by running a string from end-truss to end-truss and placing a nail at the purlin-point on each truss (the nail will keep the purlins -from sliding until they have been attached by bolts or iron straps). For local roof-covering materials such as tile, mud, or thatch, space the purlins according to local practice. For sheet metal, use the following formula: 178 Where x = Space between purlins, = Length of metal sheets, and Y each sheet will overlap 1Ocm = the length STEP 9. material. practice If 200~71 sheeting one beneath it Y - 1Ocm X = %AMPLE: the 2 will be used, the fomlu 2oocm - 1ocm c 2 = 19ocm + 2 = would then yield: each purlin. 95cm betieen Attach the roof-covering Again, follow local for local materials. Corrugated sheets should be attached with specially galvanized large-headed nails through the tops wt in the valleys, of of the curves, each sheet. Nail the sheets through attemate rises wherever the sheets overlap. third Nail them every middle of the sheets. rise y Piq +,~..,. L 7 ,. - 1 nTTAPU;\reav in the The nailing should begin at the bottom of the end of the roof farthest from the prevailing wind to minimize wind and rain that will blow between the sheets. For example, if the winds come mostly from the east, begin at the lowest part of the western end of the building. ‘( Stagger corrugated metal covering so that each row of sheets covers the joints of the row beneath. Take care also to stagger the nails line so they do not form a straight Such a straight along any purlin. line might split the purlin underneath. Patch metal metal any small holes in the with "Masticon" or a gummed tape called "Flashband". NOTE: Metal Sheet Should be Staggered 179 STEP 10. Build a crown to cover the top of the roof by cutting metal sheets lengthwise into 3 parts, pounding each part flat, bending it over the ridge of and nailing it to the the roof, metal sheets and purlins. 24?.801 0 - 77 - I4 Bamboo is an excellent building material for several ratio it has a very high strength-to-weight sturdy for such a light-weight material; l * it is easily to remove; handled, with little waste reasons: -- very and no bark it adapts to a variety of uses; a few bamboo plants in the backyard will provide enough bamboo for a extra rooms, or a house; fence, a pigpen, l 0 after construction, income-generating so on. bamboo can be used for other crafts such as baskets, mats, and About the onlypartsof a building that cannot be made rrom bamboo However, bamboo is rarely used as are fireplaces and chimneys. Usually it the only construction material for a whole building. is combined with other materials: wood, clay, lime, cement, iron, thatch, and so on. palm leaves, They differ in thitKness, strength, There are many bamboo species. Each is useful and resistance to insects and decay. flexibility, a species that For example, in only a few parts of a building. makes good supporting columns cannot be used to make screen matting The general characteristics of different species are for a window. But when in doubt about a specific bamboo supply, discussed below. the best thing to do is check local practice and/or seek advice from a local contractor. To balance construction l l its advantages, material: bamboo has many drawbacks It is usually Uneven Dimensions. necessary to ha-ve a large supply in order to weed out pieces that are too thin, too crooked, broken, or otherwise useless. Uneven surfaces. Variations in the diameter of the shaft (called a culm), in the prominence of the nodes, and in the rate of tapering at the end of the culm all make certain applications On the difficult. FQI as a 183 other hand, long culms can often be cut up and the tips used for one purpose while the shafts are used for another. l 0 Bamboo Brittleness. In almost all cases bamboo cannot be nailed. Most bonds are made with wire or hemp lashings. A few thick-walled species can be bored to insert pegs. Low durability. Bamboo is susceptible to insects (especially beetles and termites) and to rot. Both insect decay and rot can be chemically retarded, and some species are more resistant than others. But even in the best cases, bamboo cannot last much more than 5 years in weight-bearing parts of a building. for Foundations Bamboo is basically with a preservative, an above-ground material. Unless it is treated it will last only 2-3 years underground. However, bamboo will serve as a supporting post: for a house on stilts, for example. Use the largest diameter culms (at least 12-20cm) with closely spaced nodes for stiffness. If only 'smaller shafts are available, they can be bound into columns. Bamboo for Frames In earthquake areas, bamboo's flexibility makes it a good choice for construction of a frame for floors, walls, and roofs; Such a frame may then be finished by weaving bamboo to form the solid parts of the building, or by using other materials such as clay, mud, or thatch. Use only whole culms. Cut off and discard the upper, tapered ends of each culm so that all shafts used will have uniform thickness and strength. 247-80, 0 - 77 - 13 184 The design of a bamboo frame is simple: in the corners set out at Begin with corner posts firmly planted Next, attach joists (horizontal cuPms that will support the site. Then attach studs (vertical culms that will the floor and roof). form the wall frame). (STUD ? Since shafts cun be upper bamboo cannot be cut to make perfectly measured joints, the The only cut that must be lashed with vinesp bark, or wire. made is a notch or cradle-like cut that can be used at the end of posts to support a horizontal piece. 185 Bamboo for Floors The culm of certain species can be split open and flattened out, making a "board". Among other uses, these boards can be laid directly on a hard earth surface to make a floor. Clay is the best soil for this purpose. It should be evenly graded (for proper drainage) before the boards are pounded into place. BAMBOO BOARDS MADE BY SPLITTING LARGE CULM AS SHOWN Another type of bamboo floor is raised 1.5-2 meters so that the space underneath may be used for storage of equipment or anj .mals. Thick culms are used as column supports* thinner culms are flattened for the floor; and woven mats'are used as floor covering, I I Bamboo for Walls Here are two common ways to use bamboo for walls: . Wide bamboo shafts are lashed horizontally to both sides of vertical hardwood posts. Occasionally thick bamboo posts are The used instead of hardwood posts. the bamboo shafts may spaces between be filled with mud, mud and stones, or more bamboo. thatoh, l Sprung around plaster bamboo shazts are woven* _. Vertical Strip Construction. The frame is then covered wltn three horizontal poles. on one or both sides. OF PLASTER DL ,AYER OF PLASTER Partitions may be made exactly as walls are but with .lizE;a;,and Use the lightest species available. portable frames. then weave them into mats that can be suspended. flatten the shafts; Bamboo for Doors and Windows For practical reasons, doors and windows are kept to a minimum in bamboo housing. Doors tend to be made of: e wood: or, . bamboo matting woven on a bamboo frame: or, . bamboo "bars" put up in a gate-like fashion. Windows are usually unscreened and covered with bamboo matting or a palm leaf. They can also be made out of a row of shafts tightly pressed and bound together by pieces of wood: this kind of window, when acts as a shade'. raised, Bamboo for Roofs Bamboo is used for the frame be of several materials: . grass of the roof. thatch; e corrugated metal or asbestos: . tile; b bamboo tiles made from.halved culms. The roof covering can 188 Bamboo Weimforcern~t of Concrete Bamboo can'be used to increase the strength of concrete by 2 to 3 - dried the shafts must be "seasoned" To be effective, times. out and shrunk for a month or more and then split in half. The placement reinforcement page 137). Preservation The following bamboo: of the shafts is the same as the placement of iron rods (see the section on reinforcing concrete, of Bamboo simple steps will lengthen the useful life of . Cut the shafts at the base and store them upright in clumps in a dry, sheltered place. Never store bamboo out in the open or expose it to rain or dampness: It may rot or be eaten by insects. . Dust the ends of each shaft with safer insecticides talc (or other, effective). . Use pegs to keep the ends off the a mixture of 1:20 where available DDT to and 4 ground. trim all twigs and leaves . After 4-8 weeks of-drying, the shafts and dust the newly cut surfaces. off 5 LATRCNES 190 LATRINES Latrines are vital for community They keep local watar used health. for drinking or growing crops free from diseases spread through and they discourage human feces; transmission of diseases by flies that breed in excrement. In many areas, community acceptance of latrines as an integral part of any home, or clinic project may be school, more important than any other construction ideas in this manual. a latrine consists Basically, of: a p&t dug in the ground for the storage of excrement; a base built over the pit with a small hole in it so that a person can stand over the pit; and a shetter to provide privacy, protect against weather, and to keep flies from breeding in the pit. Two principal requirements should govern the choice of a latrine's location: * It should be close enough to the school, clinic, or home to but far enough away to keep the main be reached easily; 30 meters building free of odors and potential contamination. is the distance recommended by many experts. * It should be situated so that it will not contaminate ground or surface water that may enter springs, wellsip or Satisfying fields. this requirement can sometimes be complex. The most important considerations to keep in mind are: l the latrine should be high enough so it will not be flooded during the rainy season; 191 . the latrine should be &x.m~iZLfrom any nearby wells if this is impossible - of if the land is flat latrine must be at least 15 meters away from wells (?.5 meters in sandy soil); l in regions with fissured (which can carry pollution rocks or limestone great distances), or springs; the or springs foundations get expert advice! At the chosen location, begin by digging a pit, either ro;;: or and from l-3 meters deep. square, about 1 meter across, table below shows recommended depths for a latrine for a family in public of 5. The same depths may be used for latrines be 1 provided there will buiidings such as schools or clinics latrine for every 15 people who use the building regularly. RECOMMENDED DEPTHS FOR HOLES WITH 1 SQUARE METER AREA PERSONAL CLEANSING MATERIAL w-s- to pits which penetrate Wwet pit type" refers On the table, "Dry pit warer table in the ground and are constantly wet. refers to pits that are 3 meters or more above the highest underground water level. the type" If the soil is soft and tends to cave in during the digging, line the pit with stone, brick, wood, or bamboo to keep the sides of Even when the soil is firm, it's a good idea to the pit strong. line the upper few feet. The base is essentially a foundation for to prevent hookworm larvae and burrowing pit. It also helps the floor. rodents from entering the The best materials for the base are concrete from a 1:2 :3 mixture, Heavy hewn logs or stabilized earth with S-6% cement content. treated for insect resistance ray also be used as shown. Following construction of the base, a mound of Shard-packed earth or dry fill should be built up until it is level with the top of the base (at least 15cm above ground level), and it covers the floor area planned for the shelter. l&m -I Above this mound must be placed a floor with a built-in hole about Do not 40cm long and 12-18~~1 wide. make the IioZe tier than 18em or children through it! may fall The shape of the hole can vary according to local preference. common shapes are shown. Two 12cm Q 193 The floor may be built of several materials. Reinforced concrete Build a form about 1OOcm x 1OOcm and 6cm deep. is best. Then cut a piece of wood 6cm high and the size and shape of the hole This piece will act as the mold for the hole in the desired. If you slope its sides slightly instead of making concrete slab. them straight up and down, it will be easier to remove from the concrete after the concrete has set. Place the wood piece inside the 1OOcm x 1OOcm form where you want the hole to be. Then place reinforcement rods (bamboo or iron) in a grid across the formwork. Mix, pour and cure the-concrete as you would for any concrete floor (see pages 154-156). After curing,place the concrete slab over the mound and base so that the hole is centered over the pit opening. Other materials appropriate for building latrine floors include reinforced brick mortar, wood, and logs with earth. It may be desirable to add raised foot rests, approximately 30cm long and 1Ocm wide as shown. In addition, a simple wood cover can greatly reduce odors and keep flies away from the pit. Shelter The latrine . protection . shelter serves from wind several purposes: and rain; . privacy; . protection of the pit from direct and other disease-carryivg insects in the pit). In general, the shelter should long, and 1.5 meters high. be about light (darkness keeps flies and rodents from breeding 1 meter wide, It should have a shed roof with a large overhang (about The roof should be lo-15cm above the walls for ventilation diffuse any odors which might build up. 1.5 meters GO-100cm). to If acceptable socially, it is best to cut all vegetation within 2 meters of the shelter, especially if food is grown nearby. This will prevent contamination of the ground surface resulting from any possible misuse of the latrine. The illustrations above show two types actual construction of latrine shelters procedures for any building. of latrine shelter. follows the normal The One final note: The latrine design described in this manual is only one of the many possible designs. See the sources listed in the bibliography (page 227) for information on other designs. STRUCTION EARTHQUAKE AREAS 196 CONSTRUCTiON IN EARTHQUAKE AREAS In areas where earthquakes or tremors are likely, number of ways to reduce the danger of structural increase the safety of those who use a building. should be taken in: . the selection and preparation building position; a the selection of building of the site there are a damage and to Special care and the materials; . the use of special techniques for reinforcing foundations, floors, walls, and roofs. Sdectiore and Preparation of the Siie One of the simplest precautions against earthquake destruction is The to choose a site as far as possible from the fault line. fault line is the line along which two blocks of earth meet and slide against each other. Earthquakes occur when two such blocks of earth move suddenly. In areas where a serious ez r+hu-ke has occumed recently, people near the fault line will know where it is. Fault lines may also be found by looking for places where geological formations such as dry river beds or veins of rock appear to have suddenly split and shifted. The location of such shifts will be on the fault line. 197 Other suggestions for the selection of a site in earthquake areas include the following: - Flat terrain is best; avoid: sharply sloping ground if possible; ground slippage occurs most often on hills. - If the land has some slope to it, level the entire site around the building so that the foundation and walls are the same height throughout. Stepped foundations and walls of un-equal height are less stable. STEPPED FOUNDATION IS INCORRECT (Wall Height Unequa 1) LEVEL FOUNDATION IS CORRECT (Wall Height Equal) - Do not build on "filled-in" earth: it can't be as stable as ground that has settled naturally over time. - Align the building so that its length is parallel to the nearest fault line. This will help the structure go "with" and not "against" a tremor. with -. Choose a site as far from other buildings as possible. The minimum distance between l-story structures should be equal to their height. fault line. 198 - If a new building must be tdilt less than the minimum distance .from another any separation is building, better interconnect buildings. than rwne. Never of two the walls INCORRECT: Walls Connected - Use rectangular or circular shapes for buildings in Avoid earthquake areas. "L-shaped" buildings. CORRECT: Bui 1 dings Selection eb Building Separate Materials the safest materials Generally, lightest and most flexible. concrete In foundat&ms, .bamboo,and concrete or rock foundation walls to bind the rocks are in earthquake areas are the footings reinforced with iron or Avoid block foundation walls are good. because the large amounts of mortar used easily weakened in earthquakes. For waZZs, where climate permits, bamboo and wood are the best because their flexibility keeps them from cracking or collapsing, Walls made and because they are less dangerous if they do fall. from bricks or blocks of any material are fine but should be made F&mmed earth walls and rock as light and as thin as ossible. walls are unstable and %angerous in earthquakes: they should be avoided. Roofs are safest when made of bamboos and grasses (thatch). Wood-beam supported roofs are also fine, provided the material such as shingles or corrugated metal. they support is light, Adobe and tile roofs should be avoided. Reinforcemeht of Buildings There are many ways ofreinforcing buildings to resist earthquakes. The most important and least expe;?sive techniques are listed But if earthquakes.are a major problem in the local area, here. the field worker or community should consult experienced local contractors for advice. 199 All of the techniques listed here can help save a building in an whether they are used alone or in any combination. earthquake, They cannot guarantee that a building will survive a severe earthquake intact. But even in the worst case, they will give people more time to get outside safely, before the building collapses. To strengthen or iron rods. foundations To strengthen walls: . place windows . place .Inside as pass-%le; and floors, and doors doors on opposite as close reinforce them with bamboo walls: to the middle of interior walls . place timbt: posts at the ends of interior walls (see the section on window and door frames, page 96, for details of construction); l mount exterior doors so they open to the outside (this permits faster escape during a quake); . allow at least 1 meter of wall space between openings and corners; . connect all walls with interlocking wooden beame at the tops of the walls, and preferably at the floor and lintel levels too; reinforce wooden frame walls with cross- supports: TS . use a "tight" bond between brick or block courses; too much mortar will weaken the wall. . APPENQICES -e 202 1. CALCULATIONS TO CHECK SUPPORT A IBUILDING WHETHER A PROPOSED SITE WILL If there is doubt whether the soil at a proposed site will it may be necessary to estimate support a building (see page181 both the we{ght of the planned building and the weight-bearCng capacity of This section contains step-by-step directions and tables the soil. for both these estimates. IMPORTANT NOTE: The weight estimated a l its until size the builders and shape of roof be made of and how thick it will CALCULATING A BUILDING'S Several calculations per square meter. Equuttin have they will (page 101-114). must be made to estimate a building's For the purposes of estimation, figure weight that: 1. Weeht per square meter mzt = of longest (kg) To find the weight per square meter, needs to determine each of the three Equath 2. Follow these steps: Enter 1: the planned 1. length Weight per squure meter = wall (ml therefore, the planner first items on the right side of of the of longest wall (kg) weight + weight of roof supported by longest 7xrlZ (kg) of longest length Equation be WEIGHT PER SQUARE METER weight STEP 1. Equation cannot (page 22-43); what'its walls will be (page 92-951; . what kind of a planned building have decided: longest + weight wall in of roof supported by longest w&i?1 (kg) 203 STEP 2. Calculate Equation the weight of the longest wall. 1. Weight per squaxe meter length (a) Use the following equation weight of the longest’wall Equation Use Table thickness determine waZ1 Cm) the : 2 Weight of longest wall (b) to of longest weight = A to find the of the material weight with pf 1 sq. meter wall x of per sq. meter for which the building’s number of sq. meters in longest wall every centimeter of wall walls will be built. Table A wall (c) Multiply the number you find in Table A by the thickness of the building’s walls. The result will be the weight of 1 sq. meter of wall ; enter it in the correct place in Equation 2: Equation 90 concrete block stabilized earth sand-cement block adobe stone/rock 125 75 125 150 2 WeCght ,of longest ml1 (d) kg/sq. meter per centimeter wall thCckness material =cv)x n~~e;;.~er Next, multiply the length of the longest wall in meters The answer will be the number of sq. meters in the wall. figure in the correct place in Equation 2: by its height. Enter this Equation 2 Weight of longest wall = weight of 1 sq. meter of wall x of sq. in longest wall of the longes t wall based 2 in steps 2 (c) and 2(d). the weight in Equation Estimate STEP 3. longest wall. Equution the weight of the roof on the fi gures supported you have by the 1 weight of longest wa:.l (kg) Weight Per sP=e .meter (a) length of longest till (m) Use the following equation to estimate the weight of the roof supporeed by the longest wa9 1: We*t roof of szgported by longest watt (b) = = t&ght of roof per sq. meter Use Table 6 to find the estimated weight of the roo.f per sq. merer. If you are in doubt about the roof-style planned, use the figure on the table for flat Enter the figure you roofs. find in fable B in Equation 3: Equatimr3 Weight of mof supported by = longest 7x111 x nwnberof sq. meter8 in. mop Table Roof Style B Roof load per sq. m pitched 1707cg flat 19okg 205 (c) Next, multiply the length of the roof If the roof has not by its width. been planned yet, assume that it wi 11 be 1 meter longer and I meter wider The answer will than the building. be the number of square meters in the Enter this figure in the roof. correct place in Equation 3: Equation 3 Weight of roof weight of roof = per sq. meter supported by longest waZ.1 (d) Compute figures the weight of roof supported you have entered in Equation by the longest wall 3 in steps 3(b) and using 3(c). the STEP 4. Enter the figures you calculated in steps 1, 2(e), 3(c) in Equation 1, and calculate the weight of the building square meter: Equation and per i lFrom 3(c) From 2(e) : weight STEP 5. Finally, compare the building's weight per square meter with the weight-bearing capacity of the soil at the site indicated in Table C. of longest + : weight of-&of supported by TabZe C Weight-Bearing Type of SoCl Cupacitg (kg/sq. soft, b&z&, &Sned marsh, or t'filllr GraveZ, sand Hard-packed clay Rock 4,9OU-10,000 29,400 58,800 156,800 ml 206 8.7m SZQYPLECALCULATION OF A BUILDING'S WEIGHT PER SQUARE METER Here is a step-by-step sample of how the weight of a building would be estimated, following the procedure outlined on pages 202-205. Assume that the building pictured above is planned to be 7.5 wall; assume meters long and 2.4 meters high along its longest also that the walls will be made of 20cm thick sand-cement blocks, and that the roof will be 8.7 meters long and 3 meters wide, with a pitched design. If the site selected for the building is soft, dark soil that can support 4,900 kg/sq. meter, can the building be constructed as planned? Here are the calculations: -Equation 1 Weight per square meter weight of longest wall (kg) = length STEP 1. Enter Equation the length of longest of the longest weight of longest wu1.l (kg) + = (SE] nail wall 2 Weight per square meter weight of roof supported by longest wall (kg) + in Equation weight of roof supported by longest watt (kg) 1: ‘+ / :,~. I’ 207 STEP 2. (a) Calculate Use Equation Equation the weight Use Table centimeter wall. 2 A, page of wall weight to find thickness. 203, t4;4;Lply the figure . The result this answer in the of 7 sq. meter X of wizzz = the wall’s weight number of sq. meters in longest wall per square will be made of sand-cement blocks meter for every centimeter of wall Yae build&g's walls says weigh 75 kg/sq. (c) longest 2: Weight of longest wall (b) of the meter for which Table A thickness. you find in Table A by the thickness of the will be the weight of 1 square meter ,of wall. correct place in Equation 2. building’s Enter !l%e sand-cement blocks that will be used will be 2Ocm thick. So a wall made of these blocks will weigh 75 kg/sq. meter x 2Ocm thick 1500 kg/square meter. Entering this answer in Equation Weight of longest till (d) 2: x nzunber of sq. meters in longest wall = Multiply the length of the longest wall in meters enter the result in the correct place in Equation by its 2. The longest wall of the building will be 7.5 meters meters high. 7.5 x 2.4 = 18 square meters. Enterixg this answer in Equation Weight of longest wall (e) Compute entered the weight in Equation height and long and 2.4 2: 1500 kg/sq. meter x (,,.) = of the longest wall based 2 in steps 2(c) and 2(d). on the figures every you have 1500 kg/sq. meter x 18 sq. meters = 27,000 kg. Entering this result in EQuation 1: weight of roof + suported by Q5G-G) Weight per Zongest wall (kg) square meter = \7.5 meters = 208 STEP 3. Estimate longest wall. (a) Use Equation the weight of the roof supported by the 3: Equation3 Weight of = POOf supported by longest wall (b) might of roof x nwnber of per sq. meter sq. meters in roof Use Table B, page 204, to Enter this figure meter. The zvof is pZmrned with about 170 kg/%q. mter. Entering this find the estimated weight of the in the correct place in Equation a pitched answer in Equation roof that roof per square 3. Table B says will weigh 3: Weight of nwnberof sq. meters in roof mof supported by Zongest wall (c) Multiply the length of the roof by its height to meters of roof space planned. Enter this figure Equation 3. find the number of square in the correct place in The roof is plunned to be 3 meters with and 8.7 meters 3mx8.7m = 26.1 square meters. &teting this answer in Equation long. 3: Weight of roof = 170 kg/sq. meter x 6.1 square meters supported by longest wall (d) Compute figures the weight of roof supported you have entered in Equation 170 kg/sq. meter x 26.1 sq. meters result in Equation 1: Weight per square meter 27,000 kg = by the longest wall 3 in steps 3(b) and = 4,437 kg. + (TEEiks) 7.5 meters using the 3(c). Entering this 209 STEP 4. Calculate using the figures Equation 1. the weight of the building per square meter, you calculated in steps 1, 2(e), and 3(c) and 27,000 kg + 4,437 kg = 7.5 meters The building 31,437 kg 4,191 kg/sq. meter 7.5 m WiZZ weigh approximatedty STEP 5. Compare the building's with the weight-bearing capacity Table C, page 205. = 4,191 kg/sq. meter. estimated weight/square meter Use of the soil at the site. According to Table C, the weight-beating capacity of the soft, dark Since this building will soil at thCs site is 4,900 kg/sq. meter. can be built safely at weigh only 4;191 kg/sq. meter, the building th$s site. To determine whether the soil at any proposed site will support all the builder needs to do is substitute a planned building, the figures for his/her building and site in the step-by-step equations on pages 202-205, as shown. 2. STEP-BY-STEP QIRECTIONS FOR DRAWING FOUNDATION Two kinds of drawings are important aids to help the field worker and community members visualize their foundation plans and check their progress during construction: l a a cross-section wall: and view of the footing a view from above of the footing measurements, and foundation and foundation wall When a community group is ready to begin construction of the foundation, it's a good idea to help them build a small demonstration section of footing and foundation wall that they can use along with these drawings to check their progress. The demonstration section will help everyone see what they have planned to do; at the same time, it will give them practice in the construction techniques and skills Lney must use on the aktual foundatfm. DRAWING A CROSS-SECTION VIEW OF THE FOUNDATION Drawing a cross-section view of the foundation is simple. Here are examples of a cross-section for a rock foundation and for a block foundation wall. Roth drawings show concrete footings as well: :. a* .*. . ROCK FOUNDATION WALL - -‘. FOOTING * v 0 . J BLOCK FOUNDAT I ON WALL PUANS 211 DRAWING FOOTING AND FOUNDATION MEASUREMENTS (VIEW FROM ABOVE) Drawing the foundation measurements as they would look from above is also simple. Here are step-by-step instructions for drawing the foundation measurements of a sample building: 6 1. Draw a solid line representing the outside dimensions of the This walls of the building. line will also represent the outside dimensions of the foundation wall. 2. Draw a second solid lineimide the first one to represent the inside dimensions of the This line building's walls. will also represent the inside dimensions of the foundation The space betueen the two wall. lines should be exactly the width the plumed &!ZG to scale. of B (OUTS > INStDE WALL b (WIDTH I DE WALL OF WALL 3. Subtract the width of the wall from the planned width of the Divide the foundation footing. remainder in two and convert the answer into the scale dimension being used in the This figure represents drawing. the distance between the inner side of the wal! and the inner side of the fou dation footing. 4. Draw a dotted line inside the This line drawing of the walls. represents the inner dimension The space of the footing. between it and the inside solid line (step C2) should be exactly the distance calculated in step #3, 5. Draw a dotted line outside the This Pine drawing of the walls. represents the outer dimension of the footing=. The space between it and the outside solid line (step #l) should be exactly the distance calculated in step R3. Ii ,. k OUTS I DE EDG.E OF FOOTING 213 0 m r I 6. On either side of the drawing's length, add a solid line exactly as long as the longest wall (that is, the longest outer solid line). 7. On either side of the drawing's width , add a solid line exactly as long as the longest wall (that is, the longest C outer solid line). 0 MARK D I MENS IONS CALCULATED I N THE CIRCLES ON THE DRAWING 7! I I I I I I I I I I I I I -I ---------- a ------a-- t I 1 I 3 I 1 -------- -,J A- J D 8. Place a mark along each line from steps #6-7 wherever the outer wall turns a corner. Indicate the actual length of each straight section of wall. 0 MARK DIMENSIONS CALCULATED IN THE CIRCLES ON THE DRAWING -c I I I I 1 i i I I 1 I I -4 3 ---------------II 1 I !--------------- 1 3 II I I t I I I I I f , 214 9. Outside the lines drawn in steps #6-7, draw two more solid lines exactly as long as the length and width of the outer dotted line. Mark these lines to indicate the actual length of each straight section of foundation footing. 10. Underneath the completed and foundation wall will dimensions. drawing, write down what the footing be made of and their cross-section 11. The completed drawing is an actual scale drawing showing the trenches that must be dug for the footing and the dimensions of the foundation walls. Completed foundation plans: n 215 3. ESTIMATING THE AMOUNTOF CONCRETE To estimate the following the amount of concrete equation and table: needed NEEDED for a floor, FOR A FLOOR use Equation. Cubic meters of concrete needed for floor Table. = thickness of concrete Zuyer (ml floor area (sq. meters) SUGGESTEDTHICKNESS OF CONCRETEFLOORS Purpose of Floor School, STEP 1. used for Equation: x Find your Clinic, Thickness House .lOO Garage (for vehicles) .I25 Farm storage equQmwnt) (heavy .150 the thickness of the concrete building in the table, Enter Cubic meters of needed for concrete floor = STEP 2, Multiply the length of your building by its width to find out what floor space it will have. Enter this figure in the Equation: Cubic meters of concrete needed for floor = concrete (ml layer that this figure should be in the 216 / 2m In cases where the building will not be a simple rectangle, the total floor area can be determined by multiplying the length and width of each separate room and then adding the areas of all rooms together. 2m Sample CaZcuZation: Floor FZoor Floor Tote,' area Room 1 = 2m x 2.Om = 4.0 sq. area Room 2 = lm x l.Sm = 1.5 sq. aTea Room 3 = lm x l.Om = 1.0 sq. _PZoor Area = 6.5 sq, m m m m lm In round buildings, the floor area will be the radius of the building squared times 3.14. The radius is the distance from the outside of a circle to its center. Sampi!e Calculation: Floor Area = Radius (2m) x Radius i2m) x 3.14 = 4 sq. meters x 3.14 = 12.56 sq. meters STEP 3. Enter the answers you found in steps 1 and 2 in the Equation and multiply them. The answer will represent the number of cubic meters of concrete that must be purchased or made for the floor. Swnpte Calculation (u&g Cubic meters of concrete needed. = for floor . figures for round cI.inic thickness of concrete x floor layer (rn) = .lOm = 1.256 cubic meters x shown above) area (sq. meters) 12.56 sq. meters 1 I 217 4. ESTIMATING MATERIALS NEEDED This section gives step-by-step directions for calculating the materials needed to build three poured concrete, types of wall: and brick/block. rammed earth, TO BUiLD WALLS POURED CONCRETE/RAMMED EARTH FORM POURED CONCRETE AND RAMMEDEARTH To deter-mine how much poured concrete or rammed earth he/she must calculate needs, the builder how many cubic meters of material it will take to "fill" the wall space. Use the following equation: Equation. Cubic meters of nnterial needed fi3i one wall = thickess of watZ (meters) x waZZ area Isq. meters) STEP 1. Decide how thick the wall will be (see page 94 for a discussion of what to consider when planning wall thickness). Enter this figure in the correct part of the equation. STEP 2. Calculate the,wall area in square the wall's Length by its width. meters by multiplying STEP 3. Multiply the answers you found in steps 1 and 2. The result will be the cubic meters of crncrete or rammed earth you will need to build that one waZ2. STEP 4. Repeat steps 1 through 3 for each wall of the buitding. STEP 5. Add the cubic meters of concrete or rammed earth needed The result will be the tot& for all the walls of the building. number of cubic meters of concrete or rarrPned earth you will need for the buitdzng. 218 Calculating Baqs of Cement Needed for a Concrete Wall Builders who plan to purchase the cement for their concrete need Once you have to know how many sacks or bags of cement to buy. determined how many cubic meters of concrete you will need, finding the number of bags of cement is easy: just look the To use the table, answer up in Table 3, in Appendix 4 (page 222), In the case of find the concrete mixture you plan to use. first, The table will then tell the mixture would be 1:2 3/4 :4. walls, you how many cubic meters of concrete you will get from one sack Divide the number of cubic meters of concrete you plan of cement. The answer will to use by the amount you would get from one sack. be the number of sacks of cement you need to purchase. Calculating Wheelbarrowsful of Rammed Earth or Concrete Needed Hanybuilderswant to know how many wheelbarrows full of concrete or rammed earth they must bring to the construction site for wall construction: this information gives them an idea of how much work will be involved. The number of wheelbarrowsful these steps: 0 Build a form exactly many wheelbarrowsful to fill the form. needed can be estimated by following 1 cubic meter in size and count how of rammed earth or concrete it takes . Multiply this number by the total cubic meters of material that are needed for construction (from Step 5, page 216). Your answer will tell you how many wheelbarrowsful are needed, BLOCK AND BRICK WALLS To estimate the number of blocks bricks needed to build a wall, follow these steps: or 1, STEP 1. Calculate the wall area in square meters by multiplying the wall's length by its tvidth. STEP 2. Note down the nominal size of the block face. The nominal face of a block is the height and length of the block surface visible in the watt after the block is laid. 219 STEP 3. Use the table below to find how many blocks or bricks 1 square meter of the size you plan to use are needed to build of wall surface. APPROXIMATENUMBEROF BLOCKS OR BRICKS REQUIRED TO BUILD 1 SQUAREMETER WALL SURFACE Number of Blocks or Bricks Needed Nominal Size of _Face (em) 7.5 10.0 13.25 15.0 20.0 15.0 20.0 15.0 x x x x x x x x 20 30 30 30 30 40 40 60 65 32.5 25 22 16.5 16,s 12.5 12 STEP 4. Multiply the number you found in the table by the number of square meters of wall surface you found in step 1. The result will be the approsimate number of blocks or bricks needed to build the wall. Sample Calculation: How many blocks would it take to build a wall with 17 square meters surface area using blocks with a nominal face 15cm x 3&m? The table shows that 22 15cm x 3Ocm blocks are needed to build 1 square meter of wall mea. 17 sq. meters x 22 btocks/sq, meter = 374 blocks STEP 5. Repeat steps 1 through 4 for each wall of the building and add the results. The total will represent the number of blocks or bricks you must buy or make for the walls. Note: Any estimate of the number of blocks/bricks needed for a building's walls arrived at through this method will include extra blocks, since the space taken by window and door openings is treated as though it were filled in with blocks. Generally it is a good idea to buy or make these extra blocks. This will give you a margin of error for wasted or broken blocks. Calculating Mortar Quantities The amount of mortar needed to bond the blocks/bricks for a building depends on the number of blocks/bricks and their size. To calculate the amount of mortar needed for Icm thick mortar joints, follow these steps: Divide l l l the number of blocks needed For example, if the building 1536 + 100 = 15.36. 100. for the building by requires 1,536 blocks, Use the table below to find the cubic meters of mortar needed to lay 100 blocks. For example, if the nominal size of the blocks used will be 1Ocm x 20cm x 40cm, .073 cubic meters of mortar would be needed to lay every 100 blocks. Multiply the answers found in the above steps. For example, if 1,536 blocks of nominal size 1Ocm x 20cm x 40cm are needed for a building's walls, multiply 15.36 x .073. 15.36 x .073 = 1.12 cubic meters of mortar. Table 7 in Appendix 5 (page 224) may be used to determine how much cement, lime, and sand yo;l will need to make the mortar required for any building. (Mortar QUANTITIES OF MORTARREQVImD TO LAY 100 Bs!X'WSfBRIC~ for Joints lcm Thick Includhag 25% Alhxznce Nom-hat Siie of BlOCks/B2+&3 (Cd 10 x 13.25 15 x 13,25 20 10 15 20 10 15 20 10 15 20 25 30 15 x 30 x 30 x 13.25 x 30 x 15 x 30 x 15 x 30 x 15 x 30 x 20 x 30 x 20 x 30 x 20 x 30 x20 x x x x x 20 x 25 x 30 x 20 20 20 20 15 15 15 15 x x x x x x x x 40 40 40 40 40 60 60 60 x.60 cubic Meters of Miwtar .053 "053 ,067 ,065 ,065 ,070 ,061 ,061 ,076 -073 -073 .og2 ,092 l 092 t 092 .r15 ,115 ,115 for Waste) rXI 221 5. REFERENCE TABLES FQR Recommended r CONCRETE TABLE 1 Thickness of CONSTRUCTION Concrete Basement floors for dwellings Porch floors Stock barn floors Poultry house floors Hog house floors Milk house floors Granary floors Implement shed f loot-s Tile floor bases Quantities of Materials (for Mixtures 1:1:1* 1:1:2 1:1:23 1:1:3 1:1$:2 l:lf:3 1:l 3/4:2 1:l 3/4:2t 1:l 3/4:2 1~2~3 1:2:3& 1:2:4 1:2:5 1:2%:23 1:2+:3 1:2&:4 1:2%:5 1:2&:3 : 3. . 1;2&4& 1:2f:5 1:2 3/4;4 1:3:4 1:3:5 1:3:6 3/4 Slabs (cm) 10 10-12.5 12.5-15 10 10 10 12.5 15 6.25 TABLE 2 Required to Build One Cubic Meter of Aggregates 2.5 Centimeters or Less) Barrels of Cement Cubic Meters of Sand 3.56 3.23 2.90 2.64 3.04 2.44 2.75 2.64 2.44 2.24 2.07 1.95 1.73 2.32 2.18 1.31 1.68 2.11 1.98 1.82 1.82 1.62 1.74 1.66 1.49 1.36 .40 -36 .33 .30 .43 .42 .54 .51 .47 .50 .48 .44 .39 .59 055 .48 .42 :Z .51 .48 .46 .54 056 .51 746 Concrete Cub i c Mete rs of Stone .60 2: .83 .68 .84 .62 .67 .80 237 .88 25 .74 .86 .94 l 71 ::2" .87 .91 -79 -75 .84 .92 222 TABLE 3 Volume of Concrete Construction for Aggregates Not Larger than Concrete Mixtures Cubic Meters Per Sack of l:l:l$ 1:1:2 1:1:2f 1:1:3 1:1&:2 l:lf:3 1:l 3/‘+:2 it1 314~2% 1:l 3/4:23/4 1:2:3 1:2:33 1:2:4 1:2:5 of Concrete Cement Concrete Mixtures .07 .08 .03 .lO .08 1:2*:23 1:2&:3 1:2&:4 Cubic Meters Per Sack of 10 :l? 1:2&:3 .12 13 :14 l5 :15 .14 .14 17 :18 .lO 1:2+:4 10 :10 1:2+:5 l:2*:4i 1:23/4:4 1:3:4 1:3:5 1:3:6 for TABLE 4 Various Concrete Construction Concrete Floors . One Course . Heavy Duty, One Course . Farm Buildings Foundation Walls and Footings Basement Wa11,s Tanks Fence Pos t s Retaining Walls Ba rnya rd Pavements Lintels Beam Filling Silo Pits Steps of Concrete Cement 13 :15 l 03 Mixtures Sack of Cement Centimeters) 1:2%:5 1323333 .ll .12 13 :14 Suitable per 2.5 1-:1 3/4:4 1:1:2 1:2%:3 1:23/4:4 1:23:4 1:2:3 l:l:l& 1:2:3f 1:3:5 1:2:4 1:3:4 1:2t:3 1:2t:3 Projects Mixture ,:-,3: “_ >s ” ,
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