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RULE §80.25Generic Standards for Multi-Section Connections Standards

(a) Air infiltration and water vapor migration at mating surfaces: Before positioning additional sections, the mating line surfaces along the floor, endwall and ceiling, require material or procedures to limit air infiltration and water vapor migration.

  (1) Expanding Foam: Foam may be used along surfaces that are accessible after the units have been joined. Where mating line walls line up between sections, non-porous materials must be installed prior to joining the units.

  (2) Caulking: Caulking may be used along surfaces that are accessible after the units have been joined. Where mating line walls line up between sections, non-porous materials must be installed prior to joining the units.

  (3) Non-porous gasket installed along the perimeter of all mating lines.

  (4) Insulation, carpet, carpet pad or other porous materials are not acceptable.

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(b) Floor Connections:

  (1) Gaps between floors up to 1-1/2 inches maximum which do not extend the full length of the floor may be filled with lumber, plywood or other suitable shimming materials. Fastener lengths in shimmed areas may need to be increased to provide minimum 1-1/4 inches penetration into opposite floor rim joist.

  (2) Gaps less than 1/2 inch width need not be shimmed.

  (3) The floor assemblies of multi-section units must be fastened together. Fastener options and maximum spacings are listed in the floor connections figure in paragraph (4) of this subsection.

  (4) Any tears or damages to the bottom board due to fastener installation must be repaired.

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(c) Endwall Connections:

  (1) Endwalls must be fastened together at the mating line with minimum #8x4 inch wood screws or 16d nails at maximum 8 inches on-center or 12 inches on-center maximum for 5/16 lags; toed or driven straight; and

  (2) Fastener length may need to be adjusted for gaps and/or toeing, to provide minimum 1-1/2 inch penetration into opposite endwall stud.

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(d) Roof Connection: (Note: Fasteners must not be used to pull the sections together.)

  (1) Roof shall be connected with the fasteners and spacings specified in the figure in paragraph (2) of this subsection.

  (2) Gaps between the roof sections (at ridge beam and/or open beam ledgers) of up to 1-1/2 inches wide maximum which do not extend the full length of the roof must be filled with lumber and/or plywood shims. Gaps up to 1/2 inch need not be shimmed. The fastener length used in the shimmed area may need to be increased to provide a minimum 1-1/4 inch penetration into the adjacent roof structural member.

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(e) Exterior Roof Close Up:

  (1) Ensure that shingles are installed to edge of roof decking at peak. Follow nailing instructions on the shingle wrapper. Note: Wind Zone II (high wind) installations require additional fasteners.

  (2) Before installing ridge cap shingles, a minimum 6 inch wide piece of 30 gauge galvanized flashing must be installed the length of the roof.

  (3) When flashing is not continuous, lap individual pieces a minimum of 6 inches.

  (4) Fasten flashing into roof sheathing with minimum 16 gauge staples with 1 inch crown or roofing nails of sufficient length to penetrate roof decking. Maximum fastener spacing is 6 inches on-center each roof section. Place fasteners a minimum of 3/4 inches along edge of flashing.

  (5) Install ridge shingles directly on top of flashing.

  (6) Check and repair as necessary the remainder of roof for any damaged or loose shingles, remove any shipping plastic or netting, wind deflectors, etc. Make sure to seal any fastener holes with roofing cement.

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(f) Exterior Endwall Close Up: Cut closure material to the shape and size required and secure in place, starting from the bottom up, i.e.: bottom starter, vertical or horizontal siding, then roof overhang, soffit and fascia. All closure material should be fitted and sealed as required to protect the structure or interior from the elements.

(g) HVAC (heat/cooling) Duct Crossover:

  (1) Crossover duct must be listed for EXTERIOR use.

  (2) Duct R-value shall be a minimum of R-4.

  (3) The duct must be supported 48 inches on-center (maximum) and must not be allowed to touch the ground. Either strapping (minimum 1 inch wide), to hang the duct from the floor, or non-continuous pads to support it off the ground are acceptable.

  (4) The duct to the collar or plenum connections must be secured with bands or straps designed for such use. Keep duct as straight as possible to avoid kinks or bends that may restrict the airflow. Extra length must be cut off.

  (5) The installer should refer to the manufacturer's instruction for assembling the overhead duct.

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(h) Multi-Section Water Crossover:

  (1) If there is water service to other sections, connect the water supply crossover lines as shown in the applicable detail.

  (2) If the water crossover connection is not within the insulated floor envelopes, wrap the exposed water lines in insulation and secure with a good pressure sensitive tape or nonabrasive strap, or enclose the exposed portion with an insulated box.

  (3) If water piping at the inlet is exposed, a heat tape should be installed to prevent freezing. A heat tape receptacle has been provided near the water inlet. When purchasing a heat tape, it must be listed for manufactured home use, and it must be installed per manufacturer's instructions.

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(i) Drain, Waste and Vent System (DWV):

  (1) Portions of the DWV system which are below the floor may not have been installed, to prevent damage to the piping during transport. Typically, the DWV layout is designed to terminate at a single connection point to connect to the on-site sewer system. For a used home where on-site DWV connections are not assembled per the manufacturer's instructions, the DWV system must be assembled in accordance with Part 3280 of the FMHCSS.

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  (2) The following guidelines apply:

    (A) All portions of the DWV system shall be installed to provide a minimum of 1/8 inch slope per foot for a 3 inch diameter pipe or larger, in the direction of the flow. For all other pipe, a minimum of 1/4 inch is required.

    (B) Changes in direction from vertical to horizontal, and horizontal to horizontal, shall be made using long sweep elbows and/or tees.

    (C) All drain piping shall be supported at intervals not to exceed 4 feet on-center. The support may be either blocking or strapping. When strapping is used, it should be nonabrasive.

    (D) Piping must be assembled with the appropriate cleaners, primers and solvents (note: both ABS and PVC systems are common, but will require adhesives). Be sure to follow the instructions of the product used.

    (E) A cleanout must be installed at the upper (most remote) end of the floor piping system.

  (3) Water testing: At the time of installation the water system must be inspected and tested for leaks after completion at the site (the water heater must be disconnected when using an air-only test).

  (4) Drainage system testing: At the time of installation the drainage system must be inspected and tested for leaks after completion at the site.

(j) Electrical Connections: Depending on the model and/or manufacturer of the home, electrical crossovers may be located in either the front end and/or rear end of the home. Check along mating line for other labeled access panels.

  (1) Crossover connections may be one of the following:

    (A) snap or plug-in type;

    (B) junction boxes inside floor cavity (note: crossover wiring routed outside the floor cavity must be enclosed in conduit). If the boxes and/or covers are metal, they must be grounded by the use of the ground wire; or

    (C) pigtail between receptacles/switches between sections (one circuit only and enclosed in a j-box according to the National Electrical Code (NEC).

  (2) Chassis Bonding: Each chassis shall be bonded to the adjacent chassis with a solid or stranded, green insulated or bare, number 8 copper conductor. The conductor is connected to the steel chassis with a solderless lug. Alternate bonding: A 4 inch wide by 30 gauge continuous metal strap may be used as an alternate, when attached to the chassis members with two #8x3/4 inch self tapping metal screws each end of the strap.

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  (3) Electrical Crossover.

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  (4) Shipped loose equipment:

    (A) Electrical equipment such as ceiling fans, chandeliers, exterior lights, etc., which may have been shipped loose, must be installed in accordance with the adopted (NEC). Connect all corresponding color coded or otherwise marked conductors per the applicable sections of the NEC.

    (B) Bonding strap removal: 240 volt appliances (range, dryer, etc.) shall have the bonding strap removed between the ground and the neutral conductors. Cords used to connect those appliances shall be four conductor, four prong.

  (5) Main panel box feeder connection: The main panel box is wired with the grounding system separated from the neutral system (4-wire feeder). The grounding bus in the panel must be connected through a properly sized green colored insulated conductor to the service entrance equipment (meter base) located on or adjacent to the home. A licensed electrician is required to run the feeder from the pole to the main panel box in the home.

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(k) Fuel Gas Piping Systems:

  (1) Crossover Connections: All underfloor fuel gas pipe crossover connections shall be accessible and be made with the connectors supplied by the home manufacturer, or, if not available, with flexible connectors listed for exterior use and a listed quick disconnect (Method A), or a shut-off valve (Method B). When shut-off valve is used, it must be installed on the supply side of the gas piping system. The crossover connector must have a capacity rating (BTUH) of at least the total BTUHs of all appliances it serves.

  (2) Testing: The fuel gas piping system shall be subjected to an air pressure test of no less than 6 ounces and no more than 8 ounces. While the gas piping system is pressurized with air, the appliance and crossover connections shall be tested for leakage with soapy water or bubble solution. This test is required of the person connecting the gas supply to the home, but may also be performed by the gas utility or supply company.

  (3) The gas system must be inspected and tested for leaks after completion at the site.

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Source Note: The provisions of this §80.25 adopted to be effective January 29, 2008, 32 TexReg 8790; amended to be effective July 21, 2009, 34 TexReg 3254; amended to be effective January 19, 2010, 34 TexReg 8312; amended to be effective December 25, 2012, 37 TexReg 8507

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