Title 24—Housing and Urban Development--Volume 1
PART 3280—MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS
§ 3280.904   Specific requirements for designing the transportation system.
(a) General. The transportation system must be designed and constructed as an integrated unit which is safe and suitable for its specified use. In operation, the transportation system must effectively respond to the control of the towing vehicle tracking and braking, while traveling at applicable highway speeds and in normal highway traffic conditions.
(b) Specific requirements —(1) Drawbar. The drawbar must be constructed of sufficient strength, rigidity, and durability to safely withstand those dynamic forces experienced during highway transportation. It must be securely fastened to the manufactured home substructure.
(2) Coupling mechanism. The coupling mechanism (which is usually of the socket type) must be securely fastened to the drawbar in such a manner as to assure safe and effective transfer of the maximum loads, including dynamic loads, between the manufactured home structure and the hitch-assembly of the towing vehicle. The coupling must be equipped with a manually operated mechanism so adapted as to prevent disengagement of the unit while in operation. The coupling must be so designed that it can be disconnected regardless of the angle of the manufactured home to the towing vehicle.
(3) Chassis. The chassis, in conjunction with the manufactured home structure, must be constructed to effectively sustain the design loads. The integrated structure must be capable of ensuring the integrity of the complete manufactured home and ensuring against excessive deformation of structural or finish members.
(4) Running gear assembly —(i) Design criteria. The design load used to size running gear components must be the gross static dead weight minus the static tongue weight supported by the drawbar. Running gear must be designed to accept shock and vibration, both from the highway and the towing vehicle and effectively dampen these forces so as to protect the manufactured home structure from damage and fatigue. Its components must be designed to facilitate routine maintenance, inspection, and replacement.
(ii) Location. Location of the running gear assembly must be determined by documented engineering analysis, taking into account the gross weight (including all contents), total length of the manufactured home, the necessary coupling hitch weight, span distance, and turning radius. Weights shall be checked with the home in a level position ready for transport. The coupling weight must be not less than 12 percent nor more than 25 percent of the gross weight.
(5) Spring assemblies. Spring assemblies (springs, hangers, shackles, bushings, and mounting bolts) must be capable of supporting the running gear design loads, without exceeding maximum allowable stresses for design spring assembly life as recommended by the spring assembly manufacturer. The capacity of the spring system must ensure that under maximum operating load conditions, sufficient clearance is maintained between the tire and manufactured home's frame or structure to permit unimpeded wheel movement and for changing tires.
(6) Axles. Axles, and their connecting hardware, must be capable of supporting the static running gear design loads, without exceeding maximum allowable design axle loads as recommended by the axle manufacturer. The number and load capacity necessary to provide a safe tow must not be less than those required to support the design load.
(i) Recycled axles. Before reuse, all axles, including all component parts, must be reconditioned as required pursuant to a program accepted by a nationally recognized testing agency. The recycling program must be approved, and the axles must be labeled by a nationally recognized testing agency. Recycled axles and their components must utilize compatible components and be of the same size and rating as the original equipment.
(ii) [Reserved].
(7) Hubs and bearings. Hubs and bearings shall meet the requirements of § 3280.904(b)(3) and good engineering practice. Both of these components shall be accessible for inspection, routine maintenance and replacement of parts.
(8) Tires, wheels, and rims. Tires, wheels, and rims must be selected, sized, and fitted to axles so that static dead load supported by the running gear does not exceed the load capacity of the tires. Tires must not be loaded beyond the load rating marked on the sidewall of the tire or, in the absence of such a marking, the load rating specified in any of the publications of any of the organizations listed in Federal Motor Vehicle Safety Standard (FMVSS) No. 119 in 49 CFR 571.119, S5.1(b). Wheels and rims must be sized in accordance with the tire manufacturer's recommendations as suitable for use with the tires selected.
(i) Inflation pressure. The load and cold inflation pressure imposed on the rim or wheel must not exceed the rim and wheel manufacturer's instructions even if the tire has been approved for a higher load or inflation. Tire cold inflation pressure limitations and the inflation pressure measurement correction for heat must be as specified in 49 CFR 393.75(h).
(ii) Used tires. Whenever the tread depth is at least 1/16 inch as determined by a tread wear indicator, used tires are permitted to be sized in accordance with 49 CFR 571.119. The determination as to whether a used tire is acceptable must also include a visual inspection for thermal and structural defects ( e.g., dry rotting, excessive tire sidewall splitting, etc.). Used tires with such structural defects must not be installed on manufactured homes.
(9) Brake assemblies —(i) Braking axles. The number, type, size, and design of brake assemblies required to assist the towing vehicle in providing effective control and stopping of the manufactured home must be determined and documented by engineering analysis. Those alternatives listed in § 3280.903(c) may be accepted in place of such an analysis. Unless substantiated in the design to the satisfaction of the approval agency by either engineering analysis in accordance with § 3280.903(a)(1) or tests in accordance with paragraph (b)(9)(ii) of this section, there must be a minimum of two axles equipped with brake assemblies on each manufactured home transportable section.
(ii) Stopping distance. Brakes on the towing vehicle and the manufactured home (a drive-away/tow-away) must be capable of ensuring that the maximum stopping distance from an initial speed of 20 miles per hour does not exceed 35 feet in accordance with 49 CFR 393.52(d) for 2 or fewer vehicles in drive away or tow away operation.
(iii) Electrical brake wiring. Brake wiring must be provided for each brake. The brake wire must not be less than the value specified in the brake manufacturer's instructions. Aluminum wire, when used, must be provided with suitable termination that is protected against corrosion.
(10) Lamps and associated wiring. Stop lamps, turn signal/lamps, and associated wiring must meet the appropriate sections of FMVSS No. 108 in 49 CFR 571.108, which specify the performance and location of these lamps and their wiring. The manufacturer may meet these requirements by utilizing a temporary light/wiring harness, which has components that meet the FMVSS No. 108. The temporary harness is permitted to be provided by the manufactured home transportation carrier.
§ 3280.1001   Scope.
This subpart covers the requirements for attached manufactured homes and other related construction associated with manufactured homes not addressed elsewhere within this part.
§ 3280.1002   Definitions.
The following definitions are applicable to this subpart only:
Attached manufactured home. Two or more adjacent manufactured homes that are structurally independent from foundation to roof and with open space on at least two sides, but which have the appearance of a physical connection ( i.e., zero lot line).
Fire separation wall. An adjoining wall of a manufactured home that separates attached manufactured homes with a fire separation distance of less than three feet.
§ 3280.1003   Attached manufactured home unit separation.
(a) Separation requirements. (1) Attached manufactured homes shall be separated from each other by a fire separation wall of not less than 1-hour fire-resistive rating with exposure from both sides on each attached manufactured home unit when rated based on tests in accordance with ASTM E119-05 (incorporated by reference, see § 3280.4).
(2) Fire-resistance-rated floor/ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend from the foundation to the underside of the roof sheathing.
(b) Fire separation penetrations. (1) Fire rated fire separation walls must not contain through penetrations or openings.
(2) Membrane penetrations for electrical boxes are permitted on the living side of the wall under the following conditions:
(i) Steel electrical boxes not exceeding 16 square inches may be installed provided that the total area of such boxes does not exceed 100 square inches in any 100 square feet wall area. Steel electrical boxes in adjacent fire separation walls must be separated by a horizontal distance of not less than 24 inches.
(ii) Listed 2-hour fire-resistant nonmetallic electrical boxes are installed in accordance with the listings.
(iii) No other membrane penetrations are allowed.
(c) Continuity of walls. The fire separation walls for single-family attached dwelling units must be continuous from the foundation to the underside of the roof sheathing, deck, or slab and must extend the full length of the fire separation walls.
(d) Parapets. (1) Parapets constructed in accordance with paragraph (d)(2) of this section must be provided for attached manufactured homes as an extension of fire separation walls in accordance with the following:
(i) Where roof surfaces adjacent to the fire separation walls are at the same elevation, the parapet must extend not less than 30 inches above the roof surfaces.
(ii) Where roof surfaces adjacent to the wall or walls are at different elevations and the higher roof is not more than 30 inches above the lower roof surface, the parapet must not extend less than 30 inches above the lower roof surface.
(A) Parapets must be provided unless roofs are of a Class C roof covering and the roof decking or sheathing is of noncombustible materials or approved fire-retardant-treated wood for a distance of four feet on each side of the common fire separation walls; or one layer of 5/8 inch Type X gypsum board or equivalent is installed directly beneath the roof decking or sheathing for a distance of four feet on each side of the fire separation walls.
(B) A parapet must not be required where roof surfaces adjacent to the common walls are at different elevations and the higher roof is more than 30 inches above the lower roof. The fire separation wall construction from the lower roof to the underside of the higher roof deck must not have less than a 1-hour fire-resistive rating. The wall must be rated for exposure from both sides.
(2) Parapets must have the same fire resistance rating as that required for the supporting wall or walls. On any side adjacent to a roof surface, the parapet must have noncombustible faces for the uppermost 18 inches, to include counter flashing and coping materials. Where the roof slopes toward a parapet at slopes greater than 2/12 (16.7 percent slope), the parapet must extend to the same height as any portion of the roof within a distance of three feet, but in no case will the height be less than 30 inches.
§ 3280.1004   Exterior walls.
(a) The requirements of § 3280.504 for condensation control and vapor retarder installation are required to be provided on each fire separation wall of each attached manufactured home.
(b) The requirements of § 3280.506 for heat loss/gain insulation apply to the fire separation wall on each attached manufactured home.
§ 3280.1005   Electrical service.
(a) Each attached manufactured home must be supplied by only one service.
(b) Service conductors supplying one manufactured home must not pass through the interior of another manufactured home.
§ 3280.1006   Water service.
(a) Each manufactured home must have an individual water supply that will service only that unit.
(b) Each manufactured home must have a hot water supply system that will service only that unit.