[Code of Federal Regulations]
[Title 24, Volume 5]
[Revised as of April 1, 2008]
From the U.S. Government Printing Office via GPO Access
[CITE: 24CFR3280.305]

[Page 124-133]
 
                 TITLE 24--HOUSING AND URBAN DEVELOPMENT
 
 CHAPTER XX--OFFICE OF ASSISTANT SECRETARY FOR HOUSING--FEDERAL HOUSING 
        COMMISSIONER, DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT
 
PART 3280_MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS--Table of Contents
 
           Subpart D_Body and Frame Construction Requirements
 
Sec. 3280.305  Structural design requirements.

    (a) General. Each manufactured home shall be designed and 
constructed as a completely integrated structure capable of sustaining 
the design load requirements of this standard, and shall be capable of 
transmitting these loads to stabilizing devices without exceeding the 
allowable stresses or deflections. Roof framing shall be securely 
fastened to wall framing, walls to floor

[[Page 125]]

structure, and floor structure to chassis to secure and maintain 
continuity between the floor and chassis, so as to resist wind 
overturning, uplift, and sliding as imposed by design loads in this 
part. Uncompressed finished flooring greater than 1/8 inch in thickness 
shall not extend beneath load-bearing walls that are fastened to the 
floor structure.
    (b) Design loads--(1) Design dead loads. Design dead loads shall be 
the actual dead load supported by the structural assembly under 
consideration.
    (2) Design live loads. The design live loads and wind and snow loads 
shall be as specified in this section and shall be considered to be 
uniformly distributed. The roof live load or snow load shall not be 
considered as acting simultaneously with the wind load and the roof live 
or snow load and floor live loads shall not be considered as resisting 
the overturning moment due to wind.
    (3) When engineering calculations are performed, allowable unit 
stresses may be increased as provided in the documents referenced in 
Sec. 3280.304 except as otherwise indicated in Sec. Sec. 
3280.304(b)(1) and 3280.306(a).
    (4) Whenever the roof slope does not exceed 20 degrees, the design 
horizontal wind loads required by Sec. 3280.305(c)(1) may be determined 
without including the vertical roof projection of the manufactured home. 
However, regardless of the roof slope of the manufactured home, the 
vertical roof projection shall be included when determining the wind 
loading for split level or clerestory-type roof systems.
    (c) Wind, snow, and roof loads--(1) Wind loads--design requirements. 
(i) Standard wind loads (Zone I). When a manufactured home is not 
designed to resist the wind loads for high wind areas (Zone II or Zone 
III) specified in paragraph (c)(1)(ii) of this section, the manufactured 
home and each of its wind resisting parts and portions shall be designed 
for horizontal wind loads of not less than 15 psf and net uplift load of 
not less than 9 psf.
    (ii) Wind loads for high wind areas (Zone II and Zone III). When 
designed for high wind areas (Zone II and Zone III), the manufactured 
home, each of its wind resisting parts (including, but not limited to, 
shear walls, diaphragms, ridge beams, and their fastening and anchoring 
systems), and its components and cladding materials (including, but not 
limited to, roof trusses, wall studs, exterior sheathing, roofing and 
siding materials, exterior glazing, and their connections and fasteners) 
shall be designed by a Professional Engineer or Architect to resist:
    (A) The design wind loads for Exposure C specified in ANSI/ASCE 7-
88, ``Minimum Design Loads for Buildings and Other Structures,'' for a 
fifty-year recurrence interval, and a design wind speed of 100 mph, as 
specified for Wind Zone II, or 110 mph, as specified for Wind Zone III 
(Basic Wind Zone Map); or
    (B) The wind pressures specified in the following table:

                     Table of Design Wind Pressures
------------------------------------------------------------------------
                                           Wind zone II    Wind zone III
                 Element                    design wind     design wind
                                           speed 100 MPH   speed 110 MPH
------------------------------------------------------------------------
Anchorage for lateral and vertical
 stability (See Sec.  3280.306(a)):
    Net Horizontal Drag \1,2\:..........      \3\ 39 PSF   thn-eq>47 PSF
     \1,2\..............................
    Ridge beams and other Main Roof              -30 PSF         -36 PSF
     Support Beams (Beams supporting
     expanding room sections, etc.).....
Components and cladding:
    Roof trusses \4\ in all areas;           \5\ -39 PSF     \5\ -47 PSF
     trusses shall be doubled within
     3[foot]-0[foot] from each end of
     the roof...........................
    Exterior roof coverings, sheathing       \5\ -39 PSF     \5\ -47 PSF
     and fastenings \4\,\6\,\7\ in all
     areas except the following.........
        Within 3[foot]-0[foot] from each     \5\ -73 PSF     \5\ -89 PSF
         gable end (overhang at end
         wall) of the roof or endwall if
         no overhang is provided
         \4\,\6\,\7\....................
        Within 3[foot]-0[foot] from the      \5\ -51 PSF     \5\ -62 PSF
         ridge and eave (overhang at
         sidewall) or sidewall if no
         eave is provided \4\,\6\,\7\...
    Eaves (Overhangs at Sidewalls)           \5\ -51 PSF     \5\ -62 PSF
     \4\,\6\,\7\........................

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    Gables (Overhangs at Endwalls)           \5\ -73 PSF     \5\ -89 PSF
     \4\,\6\,\7\........................
Wall studs in sidewalls and endwalls,
 exterior windows and sliding glass
 doors (glazing and framing), exterior
 coverings, sheathing and fastenings
 \8\:
        Within 3[foot]-0[foot] from each  48 PSF   thn-eq>58 PSF
         endwall........................
        All other areas.................  38 PSF  thn-eq>46 PSF
------------------------------------------------------------------------
NOTES:

\1\ The net horizontal drag of 39 PSF to be used
  in calculating Anchorage for Lateral and Vertical Stability and for
  the design of Main Wind Force Resisting Systems is based on a
  distribution of wind pressures of +0.8 or +24 PSF to the windward wall
  and -0.5 or -15 PSF to the leeward wall.
\2\ Horizontal drag pressures need not be applied to roof projections
  when the roof slope does not exceed 20 degrees.
\3\ + sign would mean pressures are acting towards or on the structure;
   sign means pressures are acting away from the structure; sign means forces can act in either direction, towards
  or away from the structure.
\4\ Design values in this ``Table'' are only applicable to roof slopes
  between 10 degrees (nominal 2/12 slope) and 30 degrees.
\5\ The design uplift pressures are the same whether they are applied
  normal to the surface of the roof or to the horizontal projection of
  the roof.
\6\ Shingle roof coverings that are secured with 6 fasteners per shingle
  through an underlayment which is cemented to a 3/8'' structural rated
  roof sheathing need not be evaluated for these design wind pressures.
\7\ Structural rated roof sheathing that is at least 3/8'' in thickness,
  installed with the long dimension perpendicular to roof framing
  supports, and secured with fasteners at 4'' on center within 3[foot]-
  0[foot] of each gable end or endwall if no overhang is provided and
  6'' on center in all other areas, need not be evaluated for these
  design wind pressures.
\8\ Exterior coverings that are secured at 6 o.c. to a 3/8 structural rated sheathing that is fastened to wall framing
  members at 6 on center need not be evaluated for these
  design wind pressures.

    (iii) One-piece metal roofing capable of resisting the design wind 
pressures for ``Components and Cladding: (Exterior roof coverings)'' in 
the Table for Design Wind Pressures in this section is allowed to be 
used without structural sheathing, provided the metal roofing is tested 
using procedures that have been approved by HUD and that meet all 
requirements of Sec. Sec. 3280.303(c) and (g) and 3280.401.
    (2) Wind loads--zone designations. The Wind Zone and specific wind 
design load requirements are determined by the fastest basic wind speed 
(mph) within each Zone and the intended location, based on the Basic 
Wind Zone Map, as follows:
    (i) Wind Zone I. Wind Zone I consists of those areas on the Basic 
Wind Zone Map that are not identified in paragraphs (c)(2)(ii) or (iii) 
of this section as being within Wind Zone II or III, respectively.
    (ii) Wind Zone II.....100 mph. The following areas are deemed to be 
within Wind Zone II of the Basic Wind Zone Map:

    Local governments: The following local governments listed by State 
(counties, unless specified otherwise):
    Alabama: Baldwin and Mobile.
    Florida: All counties except those identified in paragraph 
(c)(1)(i)(C) of this section as within Wind Zone III.
    Georgia: Bryan, Camden, Chatham, Glynn, Liberty, McIntosh.
    Louisiana: Parishes of Acadia, Allen, Ascension, Assumption, 
Calcasieu, Cameron, East Baton Rouge, East Feliciana, Evangeline, 
Iberia, Iberville, Jefferson Davis, LaFayette, Livingston, Pointe 
Coupee, St. Helena, St. James, St. John the Baptist, St. Landry, St. 
Martin, St. Tammany, Tangipahoa, Vermillion, Washington, West Baton 
Rouge, and West Feliciana.
    Maine: Hancock and Washington.
    Massachusetts: Barnstable, Bristol, Dukes, Nantucket, and Plymouth.
    Mississippi: George, Hancock, Harrison, Jackson, Pearl River, and 
Stone.
    North Carolina: Beaufort, Brunswick, Camden, Chowan, Columbus, 
Craven, Currituck, Jones, New Hanover, Onslow, Pamlico, Pasquotank, 
Pender, Perquimans, Tyrrell, and Washington.
    South Carolina: Beaufort, Berkeley, Charleston, Colleton, 
Dorchester, Georgetown, Horry, Jasper, and Williamsburg.
    Texas: Aransas, Brazoria, Calhoun, Cameron, Chambers, Galveston, 
Jefferson, Kenedy, Kleberg, Matagorda, Nueces, Orange, Refugio, San 
Patricio, and Willacy.
    Virginia: Cities of Chesapeake, Norfolk, Portsmouth, Princess Anne, 
and Virginia Beach.

    (iii) Wind Zone III.....110 mph. The following areas are considered 
to be within Wind Zone III of the Basic Wind Zone Map:
    (A) States and Territories: The entire State of Hawaii, the coastal 
regions of Alaska (as determined by the 90 mph isotach on the ANSI/ASCE 
7-88 map),

[[Page 127]]

and all of the U.S. Territories of American Samoa, Guam, Northern 
Mariana Islands, Puerto Rico, Trust Territory of the Pacific Islands, 
and the United States Virgin Islands.
    (B) Local governments: The following local governments listed by 
State (counties, unless specified otherwise):

    Florida: Broward, Charlotte, Collier, Dade, Franklin, Gulf, Hendry, 
Lee, Martin, Manatee, Monroe, Palm Beach, Pinellas, and Sarasota.
    Louisiana: Parishes of Jefferson, La Fourche, Orleans, Plaquemines, 
St. Bernard, St. Charles, St. Mary, and Terrabonne.
    North Carolina: Carteret, Dare, and Hyde.

    (iv) Consideration of local requirements. For areas where local 
building code requirements exceed the design wind speed requirements of 
these standards, the Department will consider the adoption through 
rulemaking of the more stringent requirements of the State or local 
building authority.
    (3) Snow and roof loads. (i) Flat, curved and pitched roofs shall be 
designed to resist the following live loads, applied downward on the 
horizontal projection as appropriate for the design zone marked on the 
manufactured home:

------------------------------------------------------------------------
                                                                 Pounds
                                                                   per
            Zone (see Map in Sec.  3280.305(c)(4))              square
                                                                  foot
------------------------------------------------------------------------
North Zone....................................................        40
Middle Zone...................................................        30
South Zone....................................................        20
------------------------------------------------------------------------

    (A) North Roof Load Zone. The following counties in each of the 
following states are deemed to be within the North Roof Load Zone:

    Maine--Aroostook, Piscataquis, Somerset, Penobscot, Waldo, Knox, 
Hancock, and Washington.
    Alaska--All Counties

    (B) Middle Roof Load Zone. The following counties in each of the 
following states are deemed to be within the Middle Roof Load Zone:

----------------------------------------------------------------------------------------------------------------
             States                    Counties
----------------------------------------------------------------------------------------------------------------
South Dakota                     Grant                Brookings           Hanson              Lincoln
                                 Codington            Miner               Minnehaha           Yankton
                                 Deuel                Lake                Hutchinson          Union
                                 Hamlin               Moody               Turner              Clay
                                 Kingsbury            McCook
----------------------------------------------------------------------------------------------------------------
Minnesota                        Koochiching          Stearns             Renville            Sibley
                                 Itasca               Swift               McLeod              Nicollet
                                 Hubbard              Kandiyohi           Carver              Blue Earth
                                 Cass                 Meeker              Dakota              Martin
                                 Crow Wing            Wright              Goodhue             Watonwan
                                 Aitkin               Lac qui Parle       Wabasha             Brown
                                 St. Louis            Chippewa            Winona              Redwood
                                 Lake                 Yellow Medicine     Fillmore            Lyon
                                 Cook                 Mille Lacs          Mower               Lincoln
                                 Carlton              Kanabec             Olmsted             Pipestone
                                 Pine                 Benton              Dodge               Murray
                                 Wadena               Isanti              Rice                Cottonwood
                                 Todd                 Sherburne           Steele              Jackson
                                 Morrison             Anoka               Freeborn            Nobles
                                 Douglas              Chisapo             Faribault           Rock
                                 Grant                Washington          Waseca
                                 Stevens              Hennepin            Le Sueur
                                 Pope                 Ramsey              Scott
----------------------------------------------------------------------------------------------------------------
Iowa                             Hancock              Mitchell            Hamilton            Buena Vista
                                 Lyon                 Howard              Webster             Cherokee
                                 Osceola              Chickasaw           Calhoun             Plymouth
                                 Dickinson            Butler              Sac                 Sioux
                                 Emmet                Floyd               Ida                 O'Brien
                                 Kossuth              Cerro Gordo         Humboldt            Clay
                                 Winnebago            Franklin            Pocahontas          Wright
                                 Worth                Hardin              Palo Alto
----------------------------------------------------------------------------------------------------------------
Wisconsin                        Douglas              Oconto              Pepin               Lincoln
                                 Bayfield             Menominee           Pierce              Oneida
                                 Ashland              Langlade            Dunn                Polk
                                 Iron                 Marathon            Eau Claire          Burnett
                                 Vilas                Clark               Chippewa            Washburn
                                 Forest               Jackson             Rusk                Sawyer

[[Page 128]]


                                 Florence             Trempealeau         Barron              Price
                                 Marinette            Buffalo             Taylor              Door
                                 St. Croix
----------------------------------------------------------------------------------------------------------------
Michigan                         Houghton             Iron                Presque Isle        Wexford
                                 Baraga               Dickinson           Charlevoix          Benzie
                                 Marquette            Menominee           Montmorency         Grand Traverse
                                 Alger                Delta               Alpena              Kalkaska
                                 Luce                 Schoolcraft         Alcona              Oscoda
                                 Chippewa             Mackinac            Ogemaw              Otsego
                                 Keweenaw             Cheyboygan          Roscommon           Leelanau
                                 Ontonagon            Emmet               Missaukee           Antrim
                                 Gogebic              Crawford
----------------------------------------------------------------------------------------------------------------
New York                         St. Lawrence         Herkimer            Onondaga            Genesee
                                 Franklin             Lewis               Madison             Orleans
                                 Clinton              Oswego              Cayuga              Niagara
                                 Essex                Jefferson           Seneca              Erie
                                 Hamilton             Oneida              Wayne               Wyoming
                                 Warren               Fulton              Ontario             Monroe
                                 Saratoga             Montgomery          Yates
                                 Washington           Schenectady         Livingston
----------------------------------------------------------------------------------------------------------------
Massachusetts                    Essex
----------------------------------------------------------------------------------------------------------------
Maine                            Franklin             Kennebec            Lincoln             Cumberland
                                 Oxford               Androscoggin        Sagadahoc           York
----------------------------------------------------------------------------------------------------------------
Montana                          All Counties
----------------------------------------------------------------------------------------------------------------
Idaho                            All Counties
----------------------------------------------------------------------------------------------------------------
Colorado                         All Counties
----------------------------------------------------------------------------------------------------------------
Wyoming                          All Counties
----------------------------------------------------------------------------------------------------------------
Utah                             All Counties
----------------------------------------------------------------------------------------------------------------
Vermont                          Franklin             Orleans             Caledonia           Addison
                                 Grand Isle           Essex               Washington          Rutland
                                 Lamoille             Chittenden          Orange              Windsor
----------------------------------------------------------------------------------------------------------------
New Hampshire                    All Counties
----------------------------------------------------------------------------------------------------------------

    (C) South Roof Load Zone. The states and counties that are not 
listed for the North Roof Load Zone in paragraph (c)(3)(i)(A) of this 
section, or the Middle Roof Load Zone in paragraph (c)(3)(i)(B) of this 
section, are deemed to be within the South Roof Load Zone.
    (ii) For exposures in areas (mountainous or other) where snow or 
wind records or experience indicate significant differences from the 
loads stated above, the Department may establish more stringent 
requirements for homes known to be destined for such areas. For snow 
loads, such requirements are to be based on a roof snow load of 0.6 of 
the ground snow load for areas exposed to wind and a roof snow load of 
0.8 of the ground snow load for sheltered areas.
    (iii) Eaves and cornices shall be designed for a net uplift pressure 
of 2.5 times the design uplift wind pressure cited in Sec. 
3280.305(c)(1)(i) for Wind Zone I, and for the design pressures cited in 
Sec. 3280.305(c)(1)(ii) for Wind Zones II and III.
    (iv) Skylights must be capable of withstanding roof loads as 
specified in paragraphs (c)(3)(i) or (c)(3)(ii) of this section. 
Skylights must be listed and tested in accordance with AAMA 1600/I.S.7-
00, 2003, Voluntary Specification for Skylights.
    (4) Data plate requirements. The Data Plate posted in the 
manufactured home (see Sec. 3280.5) shall designate the wind and roof 
load zones or, if designed for higher loads, the actual design external 
snow and wind loads for which the home has been designed. The Data Plate 
shall include reproductions of the

[[Page 129]]

Load Zone Maps shown in this paragraph (c)(4), with any related 
information. The Load Zone Maps shall be not less than either 3\1/2\ in. 
by 2\1/4\ in., or one-half the size illustrated in the Code of Federal 
Regulations.
[GRAPHIC] [TIFF OMITTED] TR14JA94.000


[[Page 130]]


[GRAPHIC] [TIFF OMITTED] TR20OC97.004

    (d) Design load deflection. (1) When a structural assembly is 
subjected to total design live loads, the deflection for structural 
framing members shall not exceed the following (where L equals the clear 
span between supports or two times the length of a cantilever):


[[Page 131]]


Floor--L/240
Roof and ceiling--L/180
Headers, beams, and girders (vertical load)--L/180
Walls and partitions--L/180

    (2) The allowable eave or cornice deflection for uplift is to be 
measured at the design uplift load of 9 psf for Wind Zone I, and at the 
design uplift pressure cited in paragraph (c)(1)(ii) of this section for 
Wind Zones II and III. The allowable deflection shall be (2xLc)/180, 
where Lc is the measured horizontal eave projection from the wall.
    (e) Fastening of structural systems. (1) Roof framing must be 
securely fastened to wall framing, walls to floor structure, and floor 
structure to chassis, to secure and maintain continuity between the 
floor and chassis in order to resist wind overturning, uplift, and 
sliding, and to provide continuous load paths for these forces to the 
foundation or anchorage system. The number and type of fasteners used 
must be capable of transferring all forces between elements being 
joined.
    (2) For Wind Zone II and Wind Zone III, roof framing members must be 
securely fastened at the vertical bearing points to resist design 
overturning, uplift, and sliding forces. When engineered connectors are 
not installed, roof framing members must be secured at the vertical 
bearing points to wall framing members (studs), and wall framing members 
(studs) must be secured to floor framing members, with 0.016 inch base 
metal, minimum steel strapping or engineered connectors, or by a 
combination of 0.016 inch base metal, minimum steel strapping or 
engineered connectors, and structural-rated wall sheathing that overlaps 
the roof and floor system if substantiated by structural analysis or by 
suitable load tests. Steel strapping or engineered connectors are to be 
installed at a maximum spacing of 24 inches on center in Wind Zone II, 
and 16 inches on center in Wind Zone III. Exception: Where substantiated 
by structural analysis or suitable load tests, the 0.016 inch base metal 
minimum steel strapping or engineered connectors may be omitted at the 
roof to wall and/or wall to floor connections, when structural rated 
sheathing that overlaps the roof and wall and/or wall and floor is 
capable of resisting the applicable design wind loads.
    (f) Walls. The walls shall be of sufficient strength to withstand 
the load requirements as defined in Sec. 3280.305(c) of this part, 
without exceeding the deflections as specified in Sec. 3280.305(d). The 
connections between the bearing walls, floor, and roof framework members 
shall be fabricated in such a manner as to provide support for the 
material used to enclose the manufactured home and to provide for 
transfer of all lateral and vertical loads to the floor and chassis.
    (1) Except where substantiated by engineering analysis or tests, 
studs shall not be notched or drilled in the middle one-third of their 
length.
    (2) Interior walls and partitions shall be constructed with 
structural capacity adequate for the intended purpose and shall be 
capable of resisting a horizontal load of not less than five pounds per 
square foot. An allowable stress increase of 1.33 times the permitted 
published design values may be used in the design of wood framed 
interior partitions. Finish of walls and partitions shall be securely 
fastened to wall framing.
    (g) Floors. (1) Floor assemblies shall be designed in accordance 
with accepted engineering practice standards to support a minimum 
uniform live load of 40 lb/ft \2\ plus the dead load of the materials. 
In addition (but not simultaneously), floors shall be able to support a 
200-pound concentrated load on a one-inch diameter disc at the most 
critical location with a maximum deflection not to exceed one-eighth 
inch relative to floor framing. Perimeter wood joists of more than six 
inches depth shall be stabilized against overturning from superimposed 
loads as follows: at ends by solid blocking not less than two-inch 
thickness by full depth of joist, or by connecting to a continuous 
header not less than two-inch thickness and not less than the depth of 
the joist with connecting devices; at eight-feet maximum intermediate 
spacing by solid blocking or by wood cross-bridging of not less than one 
inch by three inches, metal cross-bridging of equal strength, or by 
other approved methods.

[[Page 132]]

    (2) Wood, wood fiber or plywood floors or subfloors in kitchens, 
bathrooms (including toilet compartments), laundry areas, water heater 
compartments, and any other areas subject to excessive moisture shall be 
moisture resistant or shall be made moisture resistant by sealing or by 
an overlay of nonabsorbent material applied with water-resistant 
adhesive. Use of one of the following methods would meet this 
requirement:
    (i) Sealing the floor with a water-resistant sealer; or
    (ii) Installing an overlay of a non-absorbent floor covering 
material applied with water-resistant adhesive; or
    (iii) Direct application of a water-resistant sealer to the exposed 
wood floor area when covered with a non-absorbent overlay; or
    (iv) The use of a non-absorbent floor covering which may be 
installed without a continuous application of a water-resistant adhesive 
or sealant when the floor covering meets the following criteria:
    (A) The covering is a continuous membrane with any seams or patches 
seam bonded or welded to preserve the continuity of the floor covering; 
and
    (B) The floor is protected at all penetrations in these areas by 
sealing with a compatible water-resistant adhesive or sealant to prevent 
moisture from migrating under the nonabsorbent floor covering; and
    (C) The covering is fastened around the perimeter of the subfloor in 
accordance with the floor covering manufacturer's instructions; and,
    (D) The covering is designed to be installed to prevent moisture 
penetration without the use of a water-resistant adhesive or sealer 
except as required in this paragraph (g). The vertical edges of 
penetrations for plumbing shall be covered with a moisture-resistant 
adhesive or sealant. The vertical penetrations located under the bottom 
plates of perimeter walls of rooms, areas, or compartments are not 
required to be sealed; this does not include walls or partitions within 
the rooms or areas.
    (3) Wood panel products used as floor or subfloor materials on the 
exterior of the home, such as in recessed entryways, must be rated for 
exterior exposure and protected from moisture by sealing or applying 
nonabsorbent overlay with water resistant adhesive.
    (4) Carpet or carpet pads shall not be installed under concealed 
spaces subject to excessive moisture, such as plumbing fixture spaces, 
floor areas under installed laundry equipment. Carpet may be installed 
in laundry space provided:
    (i) The appliances are not provided;
    (ii) The conditions of paragraph (g)(2) of this section are 
followed; and
    (iii) Instructions are provided to remove carpet when appliances are 
installed.
    (5) Except where substantiated by engineering analysis or tests:
    (i) Notches on the ends of joists shall not exceed one-fourth the 
joist depth.
    (ii) Holes bored in joists shall not be within 2 inches of the top 
or bottom of the joist, and the diameter of any such hole shall not 
exceed one-third the depth of the joist.
    (iii) Notches in the top or bottom of the joists shall not exceed 
one-sixth the depth and shall not be located in the middle third of the 
span.
    (6) Bottom board material (with or without patches) shall meet or 
exceed the level of 48 inch-pounds of puncture resistance as tested by 
the Beach Puncture Test in accordance with Standard Test Methods for 
Puncture and Stiffness of Paperboard, and Corrugated and Solid 
Fiberboard, ASTM D-781-1968 (73). The material shall be suitable for 
patches and the patch life shall be equivalent to the material life. 
Patch installation instruction shall be included in the manufactured 
home manufacturer's instructions.
    (h) Roofs. (1) Roofs shall be of sufficient strength to withstand 
the load requirements as defined in Sec. 3280.305 (b) and (c) without 
exceeding the deflections specified in Sec. 3280.305(d). The 
connections between roof framework members and bearing walls shall be 
fabricated in such a manner to provide for the transfer of design 
vertical and horizontal loads to the bearing walls and to resist uplift 
forces.
    (2) Roofing membranes shall be of sufficient rigidity to prevent 
deflection which would permit ponding of water or separation of seams 
due to wind, snow, ice, erection or transportation forces.

[[Page 133]]

    (3) Cutting of roof framework members for passage of electrical, 
plumbing or mechanical systems shall not be allowed except where 
substantiated by engineering analysis.
    (4) All roof penetrations for electrical, plumbing or mechanical 
systems shall be properly flashed and sealed. In addition, where a metal 
roof membrane is penetrated, a wood backer shall be installed. The 
backer plate shall be not less than \5/16\ inch plywood, with exterior 
glues, secured to the roof framing system beneath the metal roof, and 
shall be of a size to assure that all screws securing the flashing are 
held by the backer plate.
    (i) Frame construction. The frame shall be capable of transmitting 
all design loads to stabilizing devices without exceeding the allowable 
load and deflections of this section. The frame shall also be capable of 
withstanding the effects of transportation shock and vibration without 
degradation as required by subpart J.
    (1) [Reserved]
    (2) Protection of metal frames against corrosion. Metal frames shall 
be made corrosion resistant or protected against corrosion. Metal frames 
may be protected against corrosion by painting.
    (j) Welded connections. (1) All welds must be made in accordance 
with the applicable provisions of the Specification for Structural Steel 
Buildings, Allowable Stress Design and Plastic Design, AISC-S335, 1989; 
the Specification for the Design of Cold-Formed Steel Structural 
Members, AISI, 1996; and the Specification for the Design of Cold-Formed 
Stainless Steel Structural Members, SEI/ASCE 8-02, 2002.
    (2) Regardless of the provisions of any reference standard contained 
in this subpart, deposits of weld slag or flux shall be required to be 
removed only from welded joints at the following locations:
    (i) Drawbar and coupling mechanisms;
    (ii) Main member splices, and
    (iii) Spring hanger to main member connections.

[40 FR 58752, Dec. 18, 1975. Redesignated at 44 FR 20679, Apr. 6, 1979, 
as amended at 44 FR 66195, Nov. 19, 1979; 52 FR 4582, Feb. 12, 1987; 58 
FR 55006, Oct. 25, 1993; 59 FR 2469, Jan. 14, 1994; 59 FR 15113, 15114, 
Mar. 31, 1994; 62 FR 54547, Oct. 20, 1997; 70 FR 72043, Nov. 30, 2005; 
71 FR 19638, Apr. 17, 2006]