P 85 Fema P85 Apndx G

User Manual: P-85

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G. Wind Zone Comparisons
(HUD's MHCSS and
FEMA 85)
G.1 Background
HUD’s Manufactured Home Construction and Safety Standards (MHCSS; 24 CFR 3280) and its Model
Manufactured Home Installation Standards (24 CFR 3285) categorize the United States and many
of its territories and protectorates into three wind zones: Zone I, Zone II, and the highest wind
zone, Zone III.
FEMA 85, NFPA 225 Model Manufactured Home Installation Standard, and NFPA 501 Standard on
Manufactured Housing categorize the U.S. into four wind zones: Zone I, Zone II, Zone III, and
the highest wind zone, Zone IV. However, to avoid confusion, in this appendix Zones 1, 2, 3, and
4 will be used to distinguish the NFPA zones from the HUD zones.
This appendix explains the differences between the wind provisions contained in the HUD standards and those contained in FEMA 85 and the NFPA standards.

G.2 Wind Provisions
The HUD standards, FEMA 85, and the NFPA standards all contain wind provisions based on
ASCE 7, Minimum Design Loads for Buildings and Other Structures; however, they are not all based
on the same edition of ASCE 7. HUD documents are based on a modified version of the 1988
edition of ASCE 7. FEMA 85 and the NFPA standards are based on more recent editions. The
wind loads used to design FEMA 85 foundations comply with ASCE 7-02; the NFPA standards
reference ASCE 7-05.
Only minor differences exist between the wind provisions of ASCE 7-05 and ASCE 7-02; however,
the wind provisions of both ASCE 7-05 and ASCE 7-02 differ greatly from the wind provisions
of ASCE 7-88.
Two major differences exist between ASCE 7-88 and ASCE 7-05. The basic wind speed map (Figure 6-1) in ASCE 7-88 was completely redrawn in 1995 and revised in 1998. The newer maps
show high-wind zones extending much farther inland than those shown on the 1988 map. Also,
the basic wind speeds are based on different averaging times. The 1988 edition of ASCE 7 uses

PROTECTING Manufactured Homes FROM FloodS AND OTHER HazardS
A Multi-Hazard Foundation and Installation Guide

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WIND ZONE COMPARISONS (HUD'S MHCSS AND FEMA 85)

fastest mile wind speeds; ASCE 7-02 and 7-05 use 3-second gust wind speeds. The wind speeds in
the older standard are numerically less than those in the contemporary standards. For example,
ASCE 7-88 required buildings in the interior portion of the U.S. to be designed for a 70-mph
(fastest mile) wind speed; ASCE 7-02 and 7-05 place the interior portions of the U.S. in a 90-mph
(3-second gust) wind speed area. While the wind speeds are numerically greater, the design wind
loads are often not greater and, in some areas, the wind loads are less.

G.3 Wind Zones
HUD regulates wind zones as:
HUD Zone II: Areas where the basic wind speed is 100 mph (fastest mile)
HUD Zone III: Areas where the basic wind speed is 110 mph (fastest mile)
HUD Zone I includes all areas not identified as either HUD Zone II or HUD Zone III and is not
associated with a specific wind speed.
FEMA 85 and the NFPA Codes Zones identify wind zones as:
Zone 1: Areas bounded by the 90-mph isotach1 in ASCE 7-02 (ASCE 7-05 for the NFPA codes)
Zone 2: Areas between the 90-mph and the 110-mph isotachs
Zone 3: Areas between the 110-mph and the 130-mph isotachs
Zone 4: Areas between the 130-mph and the 150-mph isotachs
Figure G-1 shows the HUD wind speed map contained in 24 CFR 3280. Figure G-2 shows the
wind speed map used for FEMA 85 and the NFPA standards.
Note that the 2006 IBC Section §1609.3.1 shows the relationship between fastest mile and 3-second gust wind speeds.
Vfm = (V3 sec – 10.5)/1.05
Where: Vfm = Fastest mile wind speed (mph)
		

V3 sec = 3-second gust wind speed (mph)

1 An isotach is a line in a given surface connecting points with equal wind speeds.

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WIND ZONE COMPARISONS (HUD'S MHCSS AND FEMA 85)

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Figure G-1. Basic wind zone map for manufactured housing.
PROTECTING Manufactured Homes FROM FloodS AND OTHER Hazards
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WIND ZONE COMPARISONS (HUD'S MHCSS AND FEMA 85)

Figure G-2. NFPA 501 wind speed map.

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G.4 Wind Speeds and County Lists
Wind speeds for communities are typically determined when building codes are adopted. The
wind speeds should agree with those specified by ASCE 7, but are often decided upon by local
officials particularly in large municipalities where several wind speeds apply.
For manufactured homes, wind zones are specified by the MHCSS and are listed by State and
County. The MHCSS lists Counties contained in Wind Zones II and III. By default, all Counties
not listed as either in Zone II or III are in HUD Zone I.
The following list identifies Counties by State for the various wind zones used in FEMA 85.
Counties that are not listed or that are within the 90-mph isotach are in Zone 1.

Zone 4 (150 mph)
Florida: Broward, Martin, Miami-Dade, Monroe, Palm Beach
Louisiana: Parishes of Cameron, Lafourche, Plaquemines, St. Bernard, St. Mary, Terrebonne,
Vermillion
Mississippi: Jackson
North Carolina: Brunswick, Carteret
Texas: Cameron
The U.S. Territories of Guam, Northern Mariana Islands, Puerto Rico, Trust Territory of the Pacific Islands, and the United States Virgin Islands

Zone 3 (130 mph)
American Samoa
Alabama: Baldwin, Mobile
Alaska: The coastal regions seaward of the 110-mph isotach on the ASCE 7 map
Connecticut: Middlesex, New London
Florida: Bay, Brevard, Calhoun, Charlotte, Citrus, Collier, DeSoto, Dixie, Duval, Escambia, Flagler, Gulf, Hendry, Hernando, Hillsborough, Holmes, Indian River, Jackson, Lee, Levy, Liberty,
Manatee, Nassau, Okaloosa, Okeechobee, Pasco, Pinellas, Santa Rosa, Sarasota, St. Johns, St. Lucie, Taylor, Volusia, Wakulla, Walton, Washington
Georgia: Bryan, Camden, Chatham, Glynn, Liberty, McIntosh

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Louisiana: Parishes of Assumption, Iberia, Lafayette, Orleans, St. Charles, St. James, St. John the
Baptist, St. Martin, St. Tammany
Maryland: Somerset, Worchester
Massachusetts: Barnstable, Bristol, Dukes, Nantucket, Plymouth
Mississippi: George, Greene, Hancock, Harrison, Pearl River, Perry, Stone
New Jersey: Atlantic, Cape May, Ocean
New York: Nassau, Suffolk
North Carolina: Beaufort, Camden, Chowan, Columbus, Craven, Currituck, Dare, Hyde, Jones,
New Hanover, Onslow, Pamlico, Pasquotank, Pender, Perquimans, Tyrrell, Washington
Rhode Island: Bristol, Kent, Newport, Washington
South Carolina: Beaufort, Charleston, Georgetown, Horry
Texas: Brazoria, Calhoun, Chambers, Galveston, Jefferson, Kenedy, Kleberg, Matagorda, Nueces, Refugio, San Patricio, Willacy
Virginia: Accomack, Northampton

Zone 2 (110 mph)
Alabama: Autauga, Barbour, Bibb, Bullock, Butler, Chambers, Chilton, Choctaw, Coffee, Conecuh, Coosa, Covington, Crenshaw, Dale, Dallas, Elmore, Escambia, Macon, Montgomery, Perry,
Pike, Russell, Sumter, Tallapoosa, Washington, Wilcox
Connecticut: Fairfield, Hartford, Litchfield, New Haven, Tolland, Windham
Delaware: Kent, Sussex
Florida: Alachua, Baker, Bradford, Clay, Columbia, De Soto, Gadsden, Gilchrist, Glades, Hamilton, Hardee, Highlands, Jefferson, Lafayette, Lake, Leon, Madison, Marion, Orange, Osceola,
Putnam, Polk, Seminole, Sumter, Suwannee, Union
Georgia: Appling, Atkinson, Bacon, Baker, Baldwin, Ben Hill, Berrien, Bibb, Bleckley, Brantley, Brooks, Bulloch, Burke, Calhoun, Charlton, Chattahoochee, Clay, Clinch, Coffee, Colquitt,
Columbia, Cook, Crawford, Crisp, Decatur, Dodge, Dooly, Dougherty, Early, Echols, Effingham,
Emanuel, Evans, Glascock, Grady, Hancock, Harris, Houston, Irwin, Jeff Davis, Jefferson, Jenkins, Johnson, Jones, Lamar, Lanier, Laurens, Lee, Long, Lowndes, Macon, Marion, McDuffie,
Meriwether, Miller, Mitchell, Monroe, Montgomery, Muscogee, Peach, Pierce, Pike, Pulaski,
Quitman, Randolph, Richmond, Schley, Screven, Seminole, Stewart, Sumter, Talbot, Tattnall,
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Taylor, Telfair, Terrell, Thomas, Tift, Toombs, Treutlen, Troup, Turner, Twiggs, Upson, Ware,
Warren, Washington, Wayne, Webster, Wheeler, Wilcox, Wilkinson, Worth
Hawaii: the entire state
Louisiana: Parishes of Acadia, Allen, Ascension, Avoyelles, Beauregard, Calcasieu, Catahoula,
Concordia, East Baton Rouge, East Feliciana, Evangeline, Iberville, Jefferson Davis, Jefferson,
Livingston, Pointe Coupee, Rapides, St. Helena, St. Landry, St. Martin, Tangipahoa, Vermilion,
Vernon, Washington, West Baton Rouge, West Feliciana
Maine: Androscoggin, Cumberland, Hancock, Kennebec, Knox, Lincoln, Sagadahoc, Waldo,
York
Maryland: Caroline, Dorchester, Queen Annes, Talbot, Wicomico
Massachusetts: Bristol, Essex, Franklin, Hampden, Hampshire, Middlesex, Norfolk, Suffolk,
Worcester
Mississippi: Adams, Amite, Claiborne, Clarke, Copiah, Covington, Forrest, Franklin, Hinds, Jasper, Jefferson, Jefferson Davis, Jones, Kemper, Lamar, Lauderdale, Lawrence, Leake, Lincoln,
Marion, Neshoba, Newton, Noxubee, Pike, Rankin, Scott, Simpson, Smith, Walthall, Wayne,
Wilkinson, Winston
New Hampshire: Cheshire, Hillsborough, Merrimack, Rockingham, Strafford
New Jersey: Bergen, Burlington, Camden, Cumberland, Essex, Gloucester, Hudson, Mercer,
Middlesex, Monmouth, Morris, Passaic, Salem, Somerset, Union
New York: Bronx, Kings, New York, Putnam, Queens, Richmond, Rockland, Westchester
North Carolina: Bertie, Bladen, Cumberland, Duplin, Edgecombe, Gates, Greene, Halifax, Harnett, Hertford, Hoke, Johnston, Lenior, Martin, Nash, Northampton, Pitt, Robeson, Sampson,
Scotland, Wayne, Wilson
Pennsylvania: none
Rhode Island: Providence
South Carolina: Aiken, Allendale, Bamberg, Barnwell, Berkeley, Calhoun, Chesterfield, Clarendon, Colleton, Darlington, Dillon, Dorchester, Fairfield, Florence, Hampton, Jasper, Kershaw,
Lancaster, Lee, Lexington, Marion, Marlboro, Orangeburg, Richland, Sumter, Williamsburg
Texas: Angelina, Atascosa, Austin, Bastrop, Bee, Brooks, Burleson, Caldwell, Colorado, De Witt,
Duval, Fayette, Fort Bend, Goliad, Gonzales, Grimes, Guadalupe, Hardin, Harris, Hidalgo, Jackson, Jasper, Jim Hogg, Jim Wells, Karnes, Lavaca, Lee, Liberty, Live Oak, McMullen, Montgomery,

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Newton, Orange, Polk, San Jacinto, Starr, Trinity, Tyler, Victoria, Walker, Waller, Washington,
Webb, Wharton, Wilson, Zapata
Virginia: Gloucester, Isle of Wight, James City, Lancaster, Mathews, Middlesex, Northumberland,
Southampton, Surry, York. Cities of Chesapeake, Hampton, Newport News, Norfolk, Suffolk,
Virginia Beach

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