Subpart D Body and Frame Construction Requirements · PDF filetural Design...

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24 CFR Ch. XX (5–1–01 Edition)§ 3280.209

the listing, below the ceiling. However,when a detector is mounted on an inte-rior wall below a sloping ceiling, itshall be located 4 inches to 12 inchesbelow the intersection of the con-necting exterior wall and the slopingceiling (cathedral ceiling). The re-quired detector(s) shall be attached toan electrical outlet box and the detec-tor connected by a permanent wiringmethod into a general electrical cir-cuit. There shall be no switches in thecircuit to the detector between theover-current protection device pro-tecting the branch circuit and the de-tector. Smoke detector(s) shall not beplaced on the same branch circuit orany circuit protected by a ground faultcircuit interrupter.

[49 FR 32008, Aug. 9, 1984, as amended at 58FR 55005, Oct. 25, 1993]

§ 3280.209 Fire testing.All fire testing conducted in accord-

ance with this subpart shall be per-formed by nationally recognized test-ing laboratories which have expertisein fire technology. In case of dispute,the Secretary shall determine if a par-ticular agency is qualified to performsuch fire tests.

[49 FR 32011, Aug. 9, 1984]

Subpart D—Body and FrameConstruction Requirements

§ 3280.301 Scope.This subpart covers the minimum re-

quirements for materials, products,equipment and workmanship needed toassure that the manufactured homewill provide:

(a) Structural strength and rigidity,(b) Protection against corrosion,

decay, insects and other similar de-structive forces,

(c) Protection against hazards ofwindstorm,

(d) Resistance to the elements, and(e) Durability and economy of main-

tenance.

§ 3280.302 Definitions.The following definitions are applica-

ble to subpart D only:Anchoring equipment: means straps,

cables, turnbuckles, and chains, includ-ing tensioning devices, which are used

with ties to secure a manufacturedhome to ground anchors.

Anchoring system: means a combina-tion of ties, anchoring equipment, andground anchors that will, when prop-erly designed and installed, resist over-turning and lateral movement of themanufactured home from wind forces.

Diagonal tie: means a tie intended toprimarily resist horizontal forces, butwhich may also be used to resistvertical forces.

Footing: means that portion of thesupport system that transmits loadsdirectly to the soil.

Ground anchor: means any device atthe manufactured home stand designedto transfer manufactured home anchor-ing loads to the ground.

Loads: (1) Dead load: means theweight of all permanent constructionincluding walls, floors, roof, partition,and fixed service equipment.

(2) Live load: means the weight super-imposed by the use and occupancy ofthe manufactured home, includingwind load and snow load, but not in-cluding dead load.

(3) Wind load: means the lateral orvertical pressure or uplift on the manu-factured home due to wind blowing inany direction.

Main frame: means the structuralcomponent on which is mounted thebody of the manufactured home.

Pier: means that portion of the sup-port system between the footing andmanufactured home exclusive of capsand shims.

Sheathing: means material which isapplied on the exterior side of a build-ing frame under the exterior weatherresistant covering.

Stabilizing devices: means all compo-nents of the anchoring and support sys-tem such as piers, footings, ties, an-choring equipment, ground anchors,and any other equipment which sup-ports the manufactured home and se-cures it to the ground.

Support system: means a combinationof footings, piers, caps, and shims thatwill, when properly installed, supportthe manufactured home.

Tie: means straps, cable, or securingdevices used to connect the manufac-tured home to ground anchors.

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Office of Asst. Sec. for Housing, HUD § 3280.304

Vertical tie: means a tie intended toresist the uplifting or overturningforces.

[58 FR 55005, Oct. 25, 1993; 59 FR 15113, Mar.31, 1994]

§ 3280.303 General requirements.

(a) Minimum requirements. The designand construction of a manufacturedhome shall conform with the provisionsof this standard. Requirements for anysize, weight, or quality of materialmodified by the terms of minimum, notless than, at least, and similar expres-sions are minimum standards. Themanufacturer or installer may exceedthese standards provided such devi-ation does not result in any inferior in-stallation or defeat the purpose and in-tent of this standard.

(b) Construction. All constructionmethods shall be in conformance withaccepted engineering practices to in-sure durable, livable, and safe housingand shall demonstrate acceptableworkmanship reflecting journeymanquality of work of the various trades.

(c) Structural analysis. The strengthand rigidity of the component partsand/or the integrated structure shall bedetermined by engineering analysis orby suitable load tests to simulate theactual loads and conditions of applica-tion that occur. (See subparts E and J.)

(d) [Reserved](e) New materials and methods. (1) Any

new material or method of construc-tion not provided for in this standardand any material or method of ques-tioned suitability proposed for use inthe manufacture of the structure shallnevertheless conform in performanceto the requirements of this standard.

(2) Unless based on accepted engi-neering design for the use indicated, allnew manufactured home materials,equipment, systems or methods of con-struction not provided for in thisstandard shall be subjected to the testsspecified in paragraph (g) of this sec-tion.

(f) Allowable design stress. The designstresses of all materials shall conformto accepted engineering practice. Theuse of materials not certified as tostrength or stress grade shall be lim-ited to the minimum allowable stressesunder accepted engineering practice.

(g) Alternative test procedures. In theabsence of recognized testing proce-dures either in these standards or theapplicable provisions of those stand-ards incorporated by reference, themanufacturer electing this option shalldevelop or cause to be developed test-ing procedures to demonstrate thestructural properties and significantcharacteristics of the material, assem-bly, subassembly component or mem-ber. Such testing procedures shall be-come part of the manufacturer’s ap-proved design. (Refer to § 3280.3.)

(1) Testing procedures so developedshall be submitted to the Departmentfor approval.

(2) Upon notification of approval, thealternative test procedure is consid-ered acceptable.

(3) Such tests shall be witnessed byan independent licensed professionalengineer or architect or by a recog-nized testing organization. Copies ofthe test results shall be kept on file bythe manufactured home manufacturer.

[40 FR 58752, Dec. 18, 1975. Redesignated at 44FR 20679, Apr. 6, 1979, as amended at 58 FR55005, Oct. 25, 1993; 59 FR 2469, Jan. 14, 1994]

§ 3280.304 Materials.(a) Dimension and board lumber shall

not exceed 19 percent moisture contentat time of installation.

(b)(1) Standards for some of the gen-erally used materials and methods ofconstruction are listed in the followingtable.

Steel

Specification for Aluminum Struc-tures Construction Manual Series—Section 1, Fifth Edition—1986, The Alu-minum Association.

Specification for Structural SteelBuildings—Allowable Stress Designand Plastic Design—AISC—June 1,1989.

The following parts of this referencestandard are not applicable: 1.3.3, 1.3.4,1.3.5, 1.3.6, 1.4.6, 1.5.1.5, 1.5.5, 1.6, 1.7, 1.8,1.9, 1.10.4 through 1.10.7, 1.10.9, 1.11, 1.13,1.14.5, 1.17.7 through 1.17.9, 1.19.1, 1.19.3,1.20, 1.21, 1.23.7, 1.24, 1.25.1 through1.25.5, 1.26.4, 2.3, 2.4, 2.8 through 2.10.

Specification for the Design of Cold-Formed Steel Structural Members—AISI—1986 Edition With 1989 Adden-dum.


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.304

The following parts of this referencestandard are not applicable: 3.1.2, 4.2.1,4.2.4.

Stainless Steel Cold-Formed Struc-tural Design Manual—AISI–1974.

The following part of this referencestandard is not applicable: 3.1.2.

Standard Specifications Load Tablesand Weight Tables for Steel Joists andJoist Girders, only Sections 1–6 and thetable for ‘‘H series only’’ are applica-ble—Steel Joist Institute 1992.

Manual for Structural Applicationsof Steel Cables for Buildings—AISI–1973.

Standard Specification for Strapping,Flat Steel and Seals—ASTM D3953–91.

Wood and Wood Products

Basic Hardboard—ANSI/AHA A135.4–1982.

Prefinished Hardboard Paneling—ANSI/AHA A135.5–1988.

Hardboard Siding—ANSI/AHA A135.6–1990.

Interim Voluntary Standard forHardwood and Decorative Plywood—HPVA Interim Standard HP–1–1993.

Structural Design Guide for Hard-wood Plywood Wall Panels—HPMA De-sign Guide HP–SG–86.

For wood products—Structural GluedLaminated Timber—ANSI/AITC A190.1–1992.

Voluntary Product Standard, Con-struction and Industrial Plywood—PS–1–83.

APA Design/Construction Guide, Res-idential and Commercial—APA E30M–1993.

Design and Fabrication of All-Ply-wood Beams, Suppl. 5—APA–H 815D–1989.

Plywood Design Specification—APA–Y 510Q–1993.

Design and Fabrication of Glued Ply-wood-Lumber Beams, Suppl. 2—APA–S812P–1992.

Design and Fabrication of PlywoodCurved Panels, Suppl. 1—APA–S 811M–1990.

Design and Fabrication of PlywoodSandwich Panels, Suppl. 4—APA–U814G–1990.

Performance Standards and Policiesfor Structural Use Panels—APA–PRP–E–108P, E445N–1989.

Design and Fabrication of PlywoodStressed-Skin Panels, Suppl. 3—APA–U813K–1990.

National Design Specifications forWood Construction, 1991 Edition, WithSupplement, Design Values for WoodConstruction, AFPA.

Wood Structural Design Data, 1986Edition With 1992 Revisions, AFPA.

Span Tables for Joists and Rafters—PS–20–70, 1993, AFPA.

Design Values for Joists and Rafters,American Softwood Lumber StandardSizes, 1992, AFPA.

Design Specifications for Metal PlateConnected Wood Trusses—TPI–85.

Wood Particleboard—ANSI A208.1–1989,

Wood Flush Doors—ANSI/NWWDAI.S.1–87.

Wood Windows—ANSI/NWWDA I.S.2–87.

Wood Sliding Patio Doors—NWWDA–I.S.3–88.

Water Repellent Preservative NonPressure Treatment for Millwork—NWWDA–I.S.4–81.

Standard Test Methods for Punctureand Stiffness of Paperboard, and Cor-rugated and Solid Fiberboard—ASTMD781–68 (73).

Standard Test Methods for DirectMoisture Content Measurement ofWood and Wood-Base Materials—ASTMD4442.

Standard Test Methods for Use andCalibration of Hand-Held Moisture Me-ters—ASTM D4444–92.

Other

Standard Specification for GypsumWallboard—ASTM C36–93.

Fasteners

Application and Fastening Schedule:Power-Driven, Mechanically Drivenand Manually Driven Fasteners—HUD–FHA Use of Materials Bulletin—UM–25d–73.

Unclassified

American Society of Civil Engineer-ing Minimum Design Loads for Build-ings and Other Structures—ANSI/ASCE7–88.

Performance Standard for Wood-Based Structural Use Panels—PS–2–92,


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APA (also known as NIST StandardPS–2–92).

Safety Performance Specificationsand Methods of Test for Safety GlazingMaterials Used in Building—ANSIZ97.1–1984.

(2) Materials and methods of con-struction utilized in the design andconstruction of manufactured homeswhich are covered by the standards inthe following table, or any applicableportion thereof shall comply with theserequirements.

(3) Engineering analysis and testingmethods contained in these referencesshall be utilized to judge conformancewith accepted engineering practices re-quired in § 3280.303(c).

(4) Materials and methods of installa-tion conforming to these standardsshall be considered acceptable when in-stalled in conformance with the re-quirements of this part.

(5) Materials meeting the standards(or the applicable portion thereof) areconsidered acceptable unless otherwisespecified herein or unless substantialdoubt exists as to conformance.

(c) Wood products shall be identifiedas complying with the appropriatestandards.

[40 FR 58752, Dec. 18, 1975, as amended at 42FR 961, Jan. 4, 1977. Redesignated at 44 FR20679, Apr. 6, 1979, as amended at 58 FR 55006,Oct. 25, 1993; 59 FR 15113, Mar. 31, 1994]

§ 3280.305 Structural design require-ments.

(a) General. Each manufactured homeshall be designed and constructed as acompletely integrated structure capa-ble of sustaining the design load re-quirements of this standard, and shallbe capable of transmitting these loadsto stabilizing devices without exceed-ing the allowable stresses or deflec-tions. Roof framing shall be securelyfastened to wall framing, walls to floorstructure, and floor structure to chas-sis to secure and maintain continuitybetween the floor and chassis, so as toresist wind overturning, uplift, andsliding as imposed by design loads inthis part. Uncompressed finished floor-ing greater than 1/8 inch in thicknessshall not extend beneath load-bearingwalls that are fastened to the floorstructure.

(b) Design loads—(1) Design dead loads.Design dead loads shall be the actualdead load supported by the structuralassembly under consideration.

(2) Design live loads. The design liveloads and wind and snow loads shall beas specified in this section and shall beconsidered to be uniformly distributed.The roof live load or snow load shallnot be considered as acting simulta-neously with the wind load and theroof live or snow load and floor liveloads shall not be considered as resist-ing the overturning moment due towind.

(3) When engineering calculations areperformed, allowable unit stresses maybe increased as provided in the docu-ments referenced in § 3280.304 except asotherwise indicated in §§ 3280.304(b)(1)and 3280.306(a).

(4) Whenever the roof slope does notexceed 20 degrees, the design horizontalwind loads required by § 3280.305(c)(1)may be determined without includingthe vertical roof projection of the man-ufactured home. However, regardless ofthe roof slope of the manufacturedhome, the vertical roof projection shallbe included when determining the windloading 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 amanufactured home is not designed toresist the wind loads for high windareas (Zone II or Zone III) specified inparagraph (c)(1)(ii) of this section, themanufactured home and each of itswind resisting parts and portions shallbe designed for horizontal wind loads ofnot less than 15 psf and net uplift loadof not less than 9 psf.

(ii) Wind loads for high wind areas(Zone II and Zone III). When designedfor high wind areas (Zone II and ZoneIII), the manufactured home, each ofits wind resisting parts (including, butnot limited to, shear walls, dia-phragms, ridge beams, and their fas-tening and anchoring systems), and itscomponents and cladding materials (in-cluding, but not limited to, roof truss-es, wall studs, exterior sheathing, roof-ing and siding materials, exterior glaz-ing, and their connections and fas-teners) shall be designed by a Profes-sional Engineer or Architect to resist:


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.305

(A) The design wind loads for Expo-sure C specified in ANSI/ASCE 7–88,‘‘Minimum Design Loads for Buildingsand Other Structures,’’ for a fifty-yearrecurrence interval, and a design windspeed of 100 mph, as specified for Wind

Zone II, or 110 mph, as specified forWind Zone III (Basic Wind Zone Map);or

(B) The wind pressures specified inthe following table:

TABLE OF DESIGN WIND PRESSURES

Element

Wind zone IIdesign windspeed 100

MPH

Wind zone IIIdesign windspeed 110

MPH

Anchorage for lateral and vertical stability (See § 3280.306(a)):Net Horizontal Drag1,2™ .......................................................................................................... 3 ±39 PSF 3 ±47 PSFUplift 4: .................................................................................................................................... 5 ¥27 PSF ¥32 PSF

Main wind force resisting system:Shearwalls, Diaphragms and their Fastening and Anchorage Systems 1,2 ........................... ±39 PSF ±47 PSFRidge beams and other Main Roof Support Beams (Beams supporting expanding room

sections, etc.) ..................................................................................................................... ¥30 PSF ¥36 PSFComponents and cladding:

Roof trusses 4 in all areas; trusses shall be doubled within 3’–0’’ from each end of theroof ...................................................................................................................................... 5 ¥39 PSF 5 ¥47 PSF

Exterior roof coverings, sheathing and fastenings 4,6,7 in all areas except the following ..... 5 ¥39 PSF 5 ¥47 PSFWithin 3’–0’’ from each gable end (overhang at end wall) of the roof or endwall if no

overhang is provided 4,6,7 ............................................................................................ 5 ¥73 PSF 5 ¥89 PSFWithin 3’–0’’ from the ridge and eave (overhang at sidewall) or sidewall if no eave is

provided 4,6,7 ................................................................................................................ 5 ¥51 PSF 5 ¥62 PSFEaves (Overhangs at Sidewalls) 4,6,7 .................................................................................... 5 ¥51 PSF 5 ¥62 PSFGables (Overhangs at Endwalls) 4,6,7 .................................................................................... 5 ¥73 PSF 5 ¥89 PSF

Wall studs in sidewalls and endwalls, exterior windows and sliding glass doors (glazing andframing), exterior coverings, sheathing and fastenings 8:

Within 3’–0’’ from each corner of the sidewall and endwall ........................................... ±48 PSF ±58 PSFAll other areas ................................................................................................................. ±38 PSF ±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 pro-

jection 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 fram-

ing supports, and secured with fasteners at 4’’ on center within 3’–0’’ of each gable end or endwall if no overhang is providedand 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 at6’’ on center need not be evaluated for these design wind pressures.

(2) Wind loads—zone designations. TheWind Zone and specific wind designload requirements are determined bythe fastest basic wind speed (mph)within each Zone and the intended lo-cation, based on the Basic Wind ZoneMap, as follows:

(i) Wind Zone I. Wind Zone I consistsof those areas on the Basic Wind ZoneMap that are not identified in para-graphs (c)(2)(ii) or (iii) of this sectionas being within Wind Zone II or III, re-spectively.

(ii) Wind Zone II.....100 mph. The fol-lowing areas are deemed to be withinWind Zone II of the Basic Wind ZoneMap:

Local governments: The followinglocal governments listed by State(counties, unless specified otherwise):

Alabama: Baldwin and Mobile.Florida: All counties except those

identified in paragraph (c)(1)(i)(C) ofthis 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, EastFeliciana, Evangeline, Iberia, Iberville,Jefferson Davis, LaFayette, Living-ston, Pointe Coupee, St. Helena, St.James, St. John the Baptist, St.Landry, St. Martin, St. Tammany,


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Tangipahoa, Vermillion, Washington,West Baton Rouge, and West Feliciana.

Maine: Hancock and Washington.Massachusetts: Barnstable, Bristol,

Dukes, Nantucket, and Plymouth.Mississippi: George, Hancock, Har-

rison, 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 Wil-liamsburg.

Texas: Aransas, Brazoria, Calhoun,Cameron, Chambers, Galveston, Jeffer-son, Kenedy, Kleberg, Matagorda,Nueces, Orange, Refugio, San Patricio,and Willacy.

Virginia: Cities of Chesapeake, Nor-folk, Portsmouth, Princess Anne, andVirginia Beach.

(iii) Wind Zone III.....110 mph. The fol-lowing areas are considered to be with-in Wind Zone III of the Basic WindZone Map:

(A) States and Territories: The entireState of Hawaii, the coastal regions ofAlaska (as determined by the 90 mphisotach on the ANSI/ASCE 7–88 map),and all of the U.S. Territories of Amer-ican Samoa, Guam, Northern MarianaIslands, Puerto Rico, Trust Territoryof the Pacific Islands, and the UnitedStates Virgin Islands.

(B) Local governments: The followinglocal 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, LaFourche, Orleans, Plaquemines, St.Bernard, St. Charles, St. Mary, andTerrabonne.

North Carolina: Carteret, Dare, andHyde.

(iv) Consideration of local requirements.For areas where local building code re-quirements exceed the design windspeed requirements of these standards,

the Department will consider the adop-tion through rulemaking of the morestringent requirements of the State orlocal building authority.

(3) Snow and roof loads. (i) Flat,curved and pitched roofs shall be de-signed to resist the following liveloads, applied downward on the hori-zontal projection as appropriate for thedesign zone marked on the manufac-tured home:

Zone (see Map in § 3280.305(c)(4))

Poundsper

squarefoot

North Zone ............................................................... 40Middle Zone ............................................................. 30South Zone .............................................................. 20

(ii) For exposures in areas (moun-tainous or other) where snow or windrecords or experience indicate signifi-cant differences from the loads statedabove, the Department may establishmore stringent requirements for homesknown to be destined for such areas.For snow loads, such requirements areto be based on a roof snow load of 0.6 ofthe ground snow load for areas exposedto wind and a roof snow load of 0.8 ofthe ground snow load for shelteredareas.

(iii) Eaves and cornices shall be de-signed for a net uplift pressure of 2.5times the design uplift wind pressurecited in § 3280.305(c)(1)(i) for Wind ZoneI, and for the design pressures cited in§ 3280.305(c)(1)(ii) for Wind Zones II andIII.

(4) Data plate requirements. The DataPlate posted in the manufactured home(see § 3280.5) shall designate the windand roof load zones or, if designed forhigher loads, the actual design externalsnow and wind loads for which thehome has been designed. The DataPlate shall include reproductions of theLoad Zone Maps shown in this para-graph (c)(4), with any related informa-tion. The Load Zone Maps shall be notless than either 31⁄2 in. by 21⁄4 in., orone-half the size illustrated in the Codeof Federal Regulations.


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.305


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(d) Design load deflection. (1) When astructural assembly is subjected tototal design live loads, the deflectionfor structural framing members shall

not exceed the following (where Lequals the clear span between supportsor two times the length of a canti-lever):


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.305

Floor—L/240Roof and ceiling—L/180Headers, beams, and girders (vertical

load)—L/180Walls and partitions—L/180

(2) The allowable eave or cornice de-flection for uplift is to be measured atthe design uplift load of 9 psf for WindZone I, and at the design uplift pres-sure cited in paragraph (c)(1)(ii) of thissection for Wind Zones II and III. Theallowable deflection shall be (2 x Lc)/180, where Lc is the measured hori-zontal eave projection from the wall.

(e) Fastening of structural systems. (1)Roof framing shall be securely fastenedto wall framing, walls to floor struc-ture, and floor structure to chassis tosecure and maintain continuity be-tween the floor and chassis, so as to re-sist wind overturning, uplift, and slid-ing as specified in this part.

(2) For Wind Zones II and III, rooftrusses shall be secured to exteriorwall framing members (studs), and ex-terior wall framing members (studs)shall be secured to floor framing mem-bers, with 26 gage minimum steelstrapping or brackets or by a combina-tion of 26 gage minimum steel strap-ping or brackets and structural ratedwall sheathing that overlaps the roofand floor. Steel strapping or bracketsshall be installed at a maximum spac-ing of 24″ on center in Wind Zone II andat a maximum of 16″ on center in WindZone III. The number and type of fas-teners used to secure the steel strapsor brackets or structural sheathingshall be capable of transferring all up-lift forces between elements beingjoined.

(f) Walls. The walls shall be of suffi-cient strength to withstand the loadrequirements as defined in § 3280.305(c)of this part, without exceeding the de-flections as specified in § 3280.305(d).The connections between the bearingwalls, floor, and roof framework mem-bers shall be fabricated in such a man-ner as to provide support for the mate-rial used to enclose the manufacturedhome and to provide for transfer of alllateral and vertical loads to the floorand chassis.

(1) Except where substantiated by en-gineering analysis or tests, studs shallnot be notched or drilled in the middleone-third of their length.

(2) Interior walls and partitions shallbe constructed with structural capac-ity adequate for the intended purposeand shall be capable of resisting a hori-zontal load of not less than five poundsper square foot. An allowable stress in-crease of 1.33 times the permitted pub-lished design values may be used in thedesign of wood framed interior parti-tions. Finish of walls and partitionsshall be securely fastened to wall fram-ing.

(g) Floors. (1) Floor assemblies shallbe designed in accordance with accept-ed engineering practice standards tosupport a minimum uniform live loadof 40 lb/ft 2 plus the dead load of thematerials. In addition (but not simul-taneously), floors shall be able to sup-port a 200–pound concentrated load ona one-inch diameter disc at the mostcritical location with a maximum de-flection not to exceed one-eighth inchrelative to floor framing. Perimeterwood joists of more than six inchesdepth shall be stabilized against over-turning from superimposed loads as fol-lows: at ends by solid blocking not lessthan two-inch thickness by full depthof joist, or by connecting to a contin-uous header not less than two-inchthickness and not less than the depthof the joist with connecting devices; ateight-feet maximum intermediatespacing by solid blocking or by woodcross-bridging of not less than one inchby three inches, metal cross-bridging ofequal strength, or by other approvedmethods.

(2) Wood, wood fiber or plywoodfloors or subfloors in kitchens, bath-rooms (including toilet compartments),laundry areas, water heater compart-ments, and any other areas subject toexcessive moisture shall be moistureresistant or shall be made moisture re-sistant by sealing or by an overlay ofnonabsorbent material applied withwater-resistant adhesive. Use of one ofthe following methods would meet thisrequirement:

(i) Sealing the floor with a water-re-sistant sealer; or

(ii) Installing an overlay of a non-ab-sorbent floor covering material appliedwith water-resistant adhesive; or

(iii) Direct application of a water-re-sistant sealer to the exposed wood floor


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area when covered with a non-absorb-ent overlay; or

(iv) The use of a non-absorbent floorcovering which may be installed with-out a continuous application of awater-resistant adhesive or sealantwhen the floor covering meets the fol-lowing criteria:

(A) The covering is a continuousmembrane with any seams or patchesseam bonded or welded to preserve thecontinuity of the floor covering; and

(B) The floor is protected at all pene-trations in these areas by sealing witha compatible water-resistant adhesiveor sealant to prevent moisture frommigrating under the nonabsorbentfloor covering; and

(C) The covering is fastened aroundthe perimeter of the subfloor in accord-ance with the floor covering manufac-turer’s instructions; and,

(D) The covering is designed to be in-stalled to prevent moisture penetrationwithout the use of a water-resistantadhesive or sealer except as required inthis paragraph (g). The vertical edgesof penetrations for plumbing shall becovered with a moisture-resistant ad-hesive or sealant. The vertical penetra-tions located under the bottom platesof perimeter walls of rooms, areas, orcompartments are not required to besealed; this does not include walls orpartitions within the rooms or areas.

(3) Carpet or carpet pads shall not beinstalled under concealed spaces sub-ject to excessive moisture, such asplumbing fixture spaces, floor areasunder installed laundry equipment.Carpet may be installed in laundryspace 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 re-

move carpet when appliances are in-stalled.

(4) Except where substantiated by en-gineering analysis or tests:

(i) Notches on the ends of joists shallnot exceed one-fourth the joist depth.

(ii) Holes bored in joists shall not bewithin 2 inches of the top or bottom ofthe joist, and the diameter of any suchhole shall not exceed one-third thedepth of the joist.

(iii) Notches in the top or bottom ofthe joists shall not exceed one-sixth

the depth and shall not be located inthe middle third of the span.

(5) Bottom board material (with orwithout patches) shall meet or exceedthe level of 48 inch-pounds of punctureresistance as tested by the Beach Punc-ture Test in accordance with StandardTest Methods for Puncture and Stiff-ness of Paperboard, and Corrugated andSolid Fiberboard, ASTM D–781–1968(73). The material shall be suitable forpatches and the patch life shall beequivalent to the material life. Patchinstallation instruction shall be in-cluded in the manufactured home man-ufacturer’s instructions.

(h) Roofs. (1) Roofs shall be of suffi-cient strength to withstand the loadrequirements as defined in § 3280.305 (b)and (c) without exceeding the deflec-tions specified in § 3280.305(d). The con-nections between roof framework mem-bers and bearing walls shall be fab-ricated in such a manner to provide forthe transfer of design vertical and hori-zontal loads to the bearing walls and toresist uplift forces.

(2) Roofing membranes shall be ofsufficient rigidity to prevent deflectionwhich would permit ponding of wateror separation of seams due to wind,snow, ice, erection or transportationforces.

(3) Cutting of roof framework mem-bers for passage of electrical, plumbingor mechanical systems shall not be al-lowed except where substantiated byengineering analysis.

(4) All roof penetrations for elec-trical, plumbing or mechanical sys-tems shall be properly flashed andsealed. In addition, where a metal roofmembrane is penetrated, a wood backershall be installed. The backer plateshall be not less than 5⁄16 inch plywood,with exterior glues, secured to the roofframing system beneath the metalroof, and shall be of a size to assurethat all screws securing the flashingare held by the backer plate.

(i) Frame construction. The frameshall be capable of transmitting all de-sign loads to stabilizing devices with-out exceeding the allowable load anddeflections of this section. The frameshall also be capable of withstandingthe effects of transportation shock andvibration without degradation as re-quired by subpart J.


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.306

(1) Welded connections. (i) All weldsshall be made in accordance with theapplicable provisions of the Specifica-tion for Structural Steel Buildings, Al-lowable Stress Design and Plastic De-sign, AISC, June 1, 1989. The Specifica-tion for the Design of Cold-FormedSteel Structural Members, AISI–1986with 1989 addendum, and the StainlessSteel Cold-Formed Structural DesignManual, AISI–1974.

(ii) Regardless of the provisions ofany reference standard contained inthis subpart, deposits of weld slag orflux shall be required to be removedonly from welded joints at the fol-lowing locations:

(A) Drawbar and coupling mecha-nisms;

(B) Main member splices, and(C) Spring hanger to main member

connections.(2) Protection of metal frames against

corrosion. Metal frames shall be madecorrosion resistant or protectedagainst corrosion. Metal frames may beprotected against corrosion by paint-ing.

[40 FR 58752, Dec. 18, 1975. Redesignated at 44FR 20679, Apr. 6, 1979, as amended at 44 FR66195, 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 FR54547, Oct. 20, 1997]

§ 3280.306 Windstorm protection.(a) Provisions for support and anchor-

ing systems. Each manufactured homeshall have provisions for support/an-choring or foundation systems that,when properly designed and installed,will resist overturning and lateralmovement (sliding) of the manufac-tured home as imposed by the respec-tive design loads. For Wind Zone I, thedesign wind loads to be used for calcu-lating resistance to overturning andlateral movement shall be the simulta-neous application of the wind loads in-dicated in § 3280.305(c)(1)(i), increasedby a factor of 1.5. The 1.5 factor of safe-ty for Wind Zone I is also to be appliedsimultaneously to both the verticalbuilding projection, as horizontal windload, and across the surface of the fullroof structure, as uplift loading. ForWind Zones II and III, the resistanceshall be determined by the simulta-neous application of the horizontal

drag and uplift wind loads, in accord-ance with § 3280.305(c)(1)(ii). The basicallowable stresses of materials re-quired to resist overturning and lateralmovement shall not be increased in thedesign and proportioning of these mem-bers. No additional shape or locationfactors need to be applied in the designof the tiedown system. The dead load ofthe structure may be used to resistthese wind loading effects in all WindZones.

(1) The provisions of this sectionshall be followed and the support andanchoring systems shall be designed bya Registered Professional Engineer orArchitect.

(2) The manufacturer of each manu-factured home is required to make pro-vision for the support and anchoringsystems but is not required to providethe anchoring equipment or stabilizingdevices. When the manufacturer’s in-stallation instructions provide for themain frame structure to be used as thepoints for connection of diagonal ties,no specific connecting devices need beprovided on the main frame structure.

(b) Contents of instructions. (1) Themanufacturer shall provide printed in-structions with each manufacturedhome specifying the location and re-quired capacity of stabilizing deviceson which the design is based. The man-ufacturer shall provide drawings andspecifications certified by a registeredprofessional engineer or architect indi-cating at least one acceptable systemof anchoring, including the details ofrequired straps or cables, their endconnections, and all other devicesneeded to transfer the wind loads fromthe manufactured home to an anchor-ing or foundation system.

(2) For anchoring systems, the in-structions shall indicate:

(i) The minimum anchor capacity re-quired;

(ii) That anchors should be certifiedby a professional engineer, architect,or a nationally recognized testing lab-oratory as to their resistance, based onthe maximum angle of diagonal tieand/or vertical tie loading (see para-graph (c)(3) of this section) and angle ofanchor installation, and type of soil inwhich the anchor is to be installed;

(iii) That ground anchors should beembedded below the frost line and be at


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least 12 inches above the water table;and

(iv) That ground anchors should beinstalled to their full depth, and sta-bilizer plates should be installed toprovide added resistance to over-turning or sliding forces.

(v) That anchoring equipment shouldbe certified by a registered professionalengineer or architect to resist thesespecified forces in accordance withtesting procedures in ASTM StandardSpecification D3953–91, Standard Speci-fication for Strapping, Flat Steel andSeals.

(c) Design criteria. The provisionsmade for anchoring systems shall bebased on the following design criteriafor manufactured homes.

(1) The minimum number of ties pro-vided per side of each home shall resistdesign wind loads required in§ 3280.305(c)(1).

(2) Ties shall be as evenly spaced aspracticable along the length of themanufactured home, with not morethan two (2) feet open-end spacing oneach end.

(3) Vertical ties or straps shall be po-sitioned at studs. Where a vertical tieand a diagonal tie are located at thesame place, both ties may be connectedto a single anchor, provided that theanchor used is capable of carrying bothloadings, simultaneously.

(4) Add-on sections of expandablemanufactured homes shall have provi-sions for vertical ties at the exposedends.

(d) Requirements for ties. Manufac-tured homes in Wind Zone I requireonly diagonal ties. These ties shall beplaced along the main frame and belowthe outer side walls. All manufacturedhomes designed to be located in WindZones II and III shall have a verticaltie installed at each diagonal tie loca-tion.

(e) Protection requirements. Protectionshall be provided at sharp cornerswhere the anchoring system requiresthe use of external straps or cables.Protection shall also be provided tominimize damage to siding by thecable or strap.

(f) Anchoring equipment—load resist-ance. Anchoring equipment shall be ca-pable of resisting an allowable workingload equal to or exceeding 3,150 pounds

and shall be capable of withstanding a50 percent overload (4,725 pounds total)without failure of either the anchoringequipment or the attachment point onthe manufactured home.

(g) Anchoring equipment—weatheriza-tion. Anchoring equipment exposed toweathering shall have a resistance toweather deterioration at least equiva-lent to that provided by a coating ofzinc on steel of not less than 0.30ounces per square foot of surface coat-ed, and in accordance with the fol-lowing:

(1) Slit or cut edges of zinc-coatedsteel strapping do not need to be zinccoated.

(2) Type 1, Finish B, Grade 1 steelstrapping, 1–1/4 inches wide and 0.035inches in thickness, certified by a reg-istered professional engineer or archi-tect as conforming with ASTM Stand-ard Specification D3953–91, StandardSpecification for Strapping, Flat Steel,and Seals.

[40 FR 58752, Dec. 18, 1975. Redesignated at 44FR 20679, Apr. 6, 1979, as amended at 52 FR4583, Feb. 12, 1987; 59 FR 2473, Jan. 14, 1994]

§ 3280.307 Resistance to elements anduse.

(a) Exterior coverings shall be ofmoisture and weather resistive mate-rials attached with corrosion resistantfasteners to resist wind, snow and rain.Metal coverings and exposed metalstructural members shall be of corro-sion resistant materials or shall be pro-tected to resist corrosion. All joints be-tween portions of the exterior coveringshall be designed, and assembled toprotect against the infiltration of airand water, except for any designed ven-tilation of wall or roof cavity.

(b) Joints between dissimilar mate-rials and joints between exterior cov-erings and frames of openings shall beprotected with a compatible sealantsuitable to resist infiltration of air orwater.

(c) Where adjoining materials or as-semblies of materials are of such na-ture that separation can occur due toexpansion, contraction, wind loads orother loads induced by erection ortransportation, sealants shall be of atype that maintains protection againstinfiltration or penetration by air,moisture or vermin.


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.308

(d) Exterior surfaces shall be sealedto resist the entrance of rodents.

§ 3280.308 Formaldehyde emission con-trols for certain wood products.

(a) Formaldehyde emission levels. Allplywood and particleboard materialsbonded with a resin system or coatedwith a surface finish containing form-aldehyde shall not exceed the followingformaldehyde emission levels when in-stalled in manufactured homes:

(1) Plywood materials shall not emitformaldehyde in excess of 0.2 parts permillion (ppm) as measured by the airchamber test method specified in§ 3280.406.

(2) Particleboard materials shall notemit formaldehyde in excess of 0.3 ppmas measured by the air chamber testspecified in § 3280.406.

(b) Product certification and continuingqualification. All plywood andparticleboard materials to be installedin manufactured homes which arebonded with a resin system or coatedwith a surface finish containing form-aldehyde, other than an exclusivelyphenol-formaldehyde resin system orfinish, shall be certified by a nation-ally recognized testing laboratory ascomplying with paragraph (a) of thissection.

(1) Separate certification shall bedone for each plant where theparticleboard is produced or where theplywood or particleboard is surface-fin-ished.

(2) To certify plywood orparticleboard, the testing laboratoryshall witness or conduct the air cham-ber test specified in § 3280.406 on ran-domly selected panels initially and atleast quarterly thereafter.

(3) The testing laboratory must ap-prove a written quality control plan foreach plant where the particleboard isproduced or finished or where the ply-wood is finished. The quality controlplan must be designed to assure thatall panels comply with paragraph (a) ofthis section. The plan must establishongoing procedures to identify in-creases in the formaldehyde emissioncharacteristics of the finished productresulting from the following changes inproduction.

(i) In the case of plywood:

(A) The facility where the unfinishedpanels are produced is changed;

(B) The thickness of the panels ischanged so that the panels are thinner;or

(C) The grooving pattern on the pan-els is changed so that the grooves aredeeper or closer together.

(ii) In the case of particleboard:(A) The resin formulation is changed

so that the formaldehyde-to-urea ratiois increased;

(B) The amount of formaldehyderesin used is increased; or

(C) The press time is decreased.(iii) In the case of plywood or

particleboard:(A) The finishing or top coat is

changed and the new finishing or topcoat has a greater formaldehyde con-tent; or

(B) The amount of finishing or topcoat used on the panels is increased,provided that such finishing or topcoat contains formaldehyde.

(4) The testing laboratory shall peri-odically visit the plant to monitorquality control procedures to assurethat all certified panels meet thestandard.

(5) To maintain its certification, ply-wood or particleboard must be testedby the air chamber test specified in§ 3280.406 whenever one of the followingevents occurs:

(i) In the case of particleboard, theresin formulation is changed so thatthe formaldehyde-to-urea ratio is in-creased; or

(ii) In the case of particleboard orplywood, the finishing or top coat ischanged and the new finishing or topcoat contains formaldehyde; or

(iii) In the case of particleboard orplywood, the testing laboratory deter-mines that an air chamber test is nec-essary to assure that panels complywith paragraph (a) of this section.

(6) In the event that an air chambertest measures levels of formaldehydefrom plywood or particleboard in ex-cess of those permitted under para-graph (a) of this section, then the test-ed product’s certification immediatelylapses as of the date of production ofthe tested panels. No panel produced onthe same date as the tested panels oron any day thereafter may be used or


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certified for use in manufacturedhomes.

(i) Provided, however, that a newproduct certification may be obtainedby testing randomly selected panelswhich were produced on any day fol-lowing the date of production of thetested panels. If such panels pass theair chamber test specified in § 3280.406,then the plywood or particleboard pro-duced on that day and subsequent daysmay be used and certified for use inmanufactured homes.

(ii) Provided further, that plywood orparticleboard produced on the sameday as the tested panels, and panelsproduced on subsequent days, if notcertified pursuant to paragraph (b)(4)(i)of this section, may be used in manu-factured homes only under the fol-lowing circumstances:

(A) Each panel is treated with a scav-enger, sealant, or other means of re-ducing formaldehyde emissions whichdoes not adversely affect the structuralquality of the product; and

(B) Panels randomly selected fromthe treated panels are tested by andpass the air chamber test specified in§ 3280.406.

(c) Panel identification. Each plywoodand particleboard panel to be installedin manufactured homes which is bond-ed or coated with a resin system con-taining formaldehyde, other than anexclusively phenol-formaldehyde resinsystem, shall be stamped or labeled soas to identify the product manufac-turer, date of production and/or lotnumber, and the testing laboratorycertifying compliance with this sec-tion.

(d) Treatment after certification. If cer-tified plywood or particleboard subse-quently is treated with paint, varnish,or any other substance containingformaldehyde, then the certification isno longer valid. In such a case, eachstamp or label placed on the panelspursuant to paragraph (c) of this sec-tion must be obliterated. In addition,the treated panels may be recertifiedand reidentified in accordance withparagraphs (b) and (c) of this section.

[49 FR 32011, Aug. 9, 1984]

§ 3280.309 Health Notice on formalde-hyde emissions.

(a) Each manufactured home shallhave a Health Notice on formaldehydeemissions prominently displayed in atemporary manner in the kitchen (i.e.,countertop or exposed cabinet face).The Notice shall read as follows:

IMPORTANT HEALTH NOTICE

Some of the building materials used in thishome emit formaldehyde. Eye, nose, andthroat irritation, headache, nausea, and avariety of asthma-like symptoms, includingshortness of breath, have been reported as aresult of formaldehyde exposure. Elderly per-sons and young children, as well as anyonewith a history of asthma, allergies, or lungproblems, may be at greater risk. Researchis continuing on the possible long-term ef-fects of exposure to formaldehyde.

Reduced ventilation resulting from energyefficiency standards may allow formaldehydeand other contaminants to accumulate inthe indoor air. Additional ventilation to di-lute the indoor air may be obtained from apassive or mechanical ventilation system of-fered by the manufacturer. Consult yourdealer for information about the ventilationoptions offered with this home.

High indoor temperatures and humidityraise formaldehyde levels. When a home is tobe located in areas subject to extreme sum-mer temperatures, an air-conditioning sys-tem can be used to control indoor tempera-ture levels. Check the comfort cooling cer-tificate to determine if this home has beenequipped or designed for the installation ofan air-conditioning system.

If you have any questions regarding thehealth effects of formaldehyde, consult yourdoctor or local health department.

(b) The Notice shall be legible andtyped using letters at least 1⁄4 inch insize. The title shall be typed using let-ters at least 3⁄4 inch in size.

(c) The Notice shall not be removedby any party until the entire salestransaction has been completed (referto part 3282—Manufactured Home Pro-cedural and Enforcement Regulationsfor provisions regarding a sales trans-action).

(d) A copy of the Notice shall be in-cluded in the Consumer Manual (referto part 3283—Manufactured Home Con-sumer Manual Requirements).

[49 FR 32012, Aug. 9, 1984, as amended at 54FR 46049, Nov. 1, 1989; 58 FR 55007, Oct. 25,1993]


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24 CFR Ch. XX (5–1–01 Edition)§ 3280.401

Subpart E—Testing§ 3280.401 Structural load tests.

Every structural assembly testedshall be capable of meeting the ProofLoad Test or the Ultimate Load Testas follows:

(a) Proof load tests. Every structuralassembly tested shall be capable of sus-taining its dead load plus superimposedlive loads equal to 1.75 times the re-quired live loads for a period of 12hours without failure. Tests shall beconducted with loads applied and de-flections recorded in 1⁄4 design live loadincrements at 10–minute intervalsuntil 1.25 times design live load plusdead load has been reached. Additionalload shall then be applied continuouslyuntil 1.75 times design live load plusdead load has been reached. Assemblyfailure shall be considered as designlive load deflection (or residual deflec-tion measured 12 hours after live loadremoval) which is greater than the lim-its set in § 3280.305(d), rupture, fracture,or excessive yielding. An assembly tobe tested shall be of the minimumquality of materials and workmanshipof the production. Each test assembly,component or subassembly shall beidentified asto typeandqualityorgradeofmaterial.All assemblies, components or sub-assemblies qualifying under this sec-tion shall be subject to a continuingqualification testing program accept-able to the Department.

(b) Ultimate load tests. Ultimate loadtests shall be performed on a minimumof three assemblies or components togenerally evaluate the structural de-sign. Every structural assembly orcomponent tested shall be capable ofsustaining its total dead load plus thedesign live load increased by a factor ofsafety of at least 2.5. A factor of safetygreater than 2.5 shall be used when re-quired by an applicable referencestandard in § 3280.304(b)(1). Tests shallbe conducted with loads applied and de-flections recorded in 1⁄4 design live loadincrements at 10-minute intervals until1.25 times design live load plus deadload has been reached. Additional load-ing shall then be applied continuouslyuntil failure occurs or the total of thefactor of safety times the design liveload plus the dead load is reached. As-

sembly failure shall be considered asdesign live load deflection greater thanthe limits set in § 3208.305(d), rupture,fracture, or excessive yielding. Assem-blies to be tested shall be representa-tive of average quality or materialsand workmanship of the production.Each test assembly, component, or sub-assembly shall be identified as to typeand quality or grade of material. Allassemblies, components, or sub-assem-blies qualifying under this section shallbe subject to a periodic qualificationtesting program acceptable to the De-partment.

[40 FR 58752, Dec. 18, 1975. Redesignated at 44FR 20679, Apr. 6, 1979, as amended at 58 FR55007, Oct. 25, 1993]

§ 3280.402 Test procedure for rooftrusses.

(a) Roof load tests. The following is anacceptable test procedure, consistentwith the provisions of § 3280.401, for rooftrusses that are supported at the endsand support design loads. Where rooftrusses act as support for other mem-bers, act as cantilevers, or support con-centrated loads, they shall be testedaccordingly.

(b) General. Trusses may be tested inpairs or singly in a suitable test facil-ity. When tested singly, simulated lat-eral support of the test assembly maybe provided, but in no case shall thislateral support exceed that which isspecified for the completed manufac-tured home. When tested in pairs, thetrusses shall be spaced at the designspacing and shall be mounted on solidsupport accurately positioned to givethe required clear span distance (L) asspecified in the design. The top andbottom chords shall be braced and cov-ered with the material, with connec-tions or method of attachment, asspecified by the completed manufac-tured home.

(1) As an alternate test procedure,the top chord may be sheathed with 1⁄4inch by 12 inch plywood strips. The ply-wood strips shall be at least longenough to cover the top chords of thetrusses at the designated design trussspacing. Adjacent plywood strips mustbe separated by at least 1⁄8 inch. Theplywood strip shall be nailed with 4dnails or equivalent staples not closerthan 8 inches on center along the top


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