Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-150I - Manufactured and mobile home installation › MANUFACTURED HOME INSTALLATION REQUIREMENTS › Section 296-150I-0310 - Instructions for manufactured home installation

Current through Register Vol. 24-14, July 15, 2024
The installation of all manufactured homes shall comply with
				  the requirements of this section.
(1)
				Installation of a new manufactured home.
(a)
				The installation of a new manufactured home must be conducted according to the
				manufacturer's instructions.
(b) If
				the manufacturer's instructions do not address an aspect of the installation,
				you may request:
(i) Specific instructions
				from the manufacturer; or
(ii)
				Specific instructions from a professional engineer or architect licensed in
				Washington state. For example:
* A manufactured home is installed over a basement and the
				  manufacturer's instructions do not address this application;
* A manufactured home is installed on a site where the
				  specific soil bearing capacity is not addressed in the manufacturer's
				  instructions.
(c) All manufactured homes installed in
				Washington state must be permanently anchored except for those installed on
				dealer lots. On dealer lots, temporary sets are permitted without anchoring
				being installed. A manufactured home must be anchored according to the
				manufacturer's installation instructions or according to the design of a
				professional engineer or architect licensed in Washington state. Local
				jurisdictions may not prescribe anchoring methods.
(d) A manufactured home must have a skirting
				around its entire perimeter. Skirting must be installed in accordance with the
				manufacturer's installation instructions or if the manufacturer is not
				specific, to the standards in this section. Do not enclose with skirting, areas
				under recessed entries, porches or decks, (whether constructed as part of the
				home or added on site) unless skirting is of the fully vented type and
				installed so as to allow water to freely flow out from under the home. Porch
				areas open to the crawl space area of the home must have the vapor retarder
				removed and the ground directly below the porch must slope away from the home.
				Skirting must be vented and allow access to the under floor area in accordance
				with the manufacturer's installation instructions or as required below if the
				manufacturer's instructions are not available.
If the manufacturer's skirting and access instructions are
				  not specific, skirting, ventilation and access shall be installed as
				  follows:
(i) Skirting:
* Must be made of materials suitable for ground
				  contact.
* Metal fasteners must be made of galvanized, stainless steel
				  or other corrosion-resistant material.
* Ferrous metal members in contact with the earth, except
				  those made of galvanized or stainless steel, must be coated with an asphaltic
				  emulsion.
* Must not trap water between the skirting and siding or
				  trim.
* Must be recessed behind the siding or trim.
(ii) Ventilation:
For homes sited in a flood plain, contact the local
				  jurisdiction regarding proper skirting ventilation. Except for those
				  manufactured homes sited in a flood plain, all skirting and vent openings
				  must:
* Be covered with corrosion-resistant wire mesh to prevent
				  the entrance of rodents. The size of the mesh opening cannot exceed 1/4
				  inch.
* Have a net area of not less than one square foot for each
				  one hundred fifty square feet of under floor area.
* Be located as close to corners and as high as practical and
				  provide cross ventilation on at least two opposite sides.
(iii) Access:
* The under floor area of a manufactured home must have a
				  finished opening at least eighteen inches by twenty-four inches in size.
* Opening must be located so that all areas under a
				  manufactured home are available for inspection.
* Opening must be covered. The cover must be made of material
				  suitable for skirting or venting as required in this chapter.
(e) A manufactured home site must
				be prepared in accordance with the manufacturer's installation manual or to the
				requirements of the Model Manufactured Home Installation Standards 24 C.F.R.
				Part 3285 , Subpart C.
(f) If the
				home is pit set, a drainage system must be installed to divert groundwater from
				the underside of the home.
(g) Heat
				duct crossovers must be installed in accordance with the manufacturer's
				installation instruction manual or if the manufacturer's instructions are not
				available, to the requirements in the Model Manufactured Home Installation
				Standards 24 C.F.R. Part 3285.606 .
Heat duct crossovers must be installed to avoid standing
				  water and installed to prevent compression, sharp bends, and to minimize stress
				  at the connections. In all cases, the duct must be supported at least one inch
				  off the ground (exception to the Model Manufactured Home Installation Standards
				  24 C.F.R. Part 3285 ).
(h)
				Dryer vents must exhaust to the exterior side of the wall or skirting. Dryer
				ducts outside the manufactured home shall comply with the dryer manufacturer's
				specifications or shall be made of metal with smooth interior
				surfaces.
(i) Water heater pans are
				only required where the installation instructions specifically require a pan
				for warranty or the home was produced after May 31, 2006. The water heater pan
				drain line must drain to the exterior of the home. The water heater pan drain
				line and the PRV drain line must not be interconnected.
(j) Water heater expansion tanks are not
				required by the department; however, you should check with your local
				jurisdiction for their requirements prior to installation.
(k) Water piping must be protected against
				freezing in accordance with the manufacturer's installation instructions or by
				use of a heat tape listed for use with manufactured homes and installed as
				required by the heat tape manufacturer's installation instructions.
(l) The testing of water lines, waste lines,
				gas lines, and electrical systems must comply with the manufacturer's
				installation instructions. If the manufacturer's installation instructions
				require testing of any of these systems, the local jurisdiction is responsible
				for verifying that the tests have been performed and passed. Electrical
				connections and testing are the responsibility of the electrical section of
				labor and industries except where a city has assumed the electrical inspection
				responsibilities for their jurisdiction. In that case, the city's electrical
				inspectors are responsible for the electrical connections and
				testing.
(m) A vapor retarder must
				be installed under all manufactured homes. Joints in vapor retarders must
				overlap a minimum of twelve inches. Voids, cuts, and tears in the vapor
				retarder must be patched or repaired with an approved method.
(n) Clearances underneath manufactured homes
				must be maintained at a minimum of eighteen inches beneath at least
				seventy-five percent of the lowest member of the main frame (I-beam or channel
				beam) and the ground or footing. In no case shall clearance be less than twelve
				inches anywhere under the home and eighteen inches at the heat duct cross over
				locations.
(o) Heat pump and air
				conditioning condensation lines must be extended to the exterior of the
				manufactured home.
(p) Roof ridge
				cap or ridge vent must be installed as required by the manufacturer's
				installation instructions.