Chapter 15.08


15.08.010    Mobile home defined.

15.08.020    General installation requirements.

15.08.030    Installation permits.

15.08.040    Inspections.

15.08.050    Disputes.

15.08.060    Building site preparation.

15.08.070    Foundation system footings.

15.08.080    Foundation system piers.

15.08.090    Foundation system plates and shims.

15.08.100    Foundation facia.

15.08.110    Assembly.

15.08.120    Fees.

15.08.130    Administration and enforcement.

15.08.010 Mobile home defined.

A “mobile home” means a structure, transportable in one or more sections, which is eight body feet or more in width or 32 body feet or more in length, built on a permanent chassis and designed for human occupancy with or without a permanent foundation when connected to the required utilities, and includes the plumbing, heating, air conditioning, and electrical systems contained therein. (Ord. 645 § 1, 1983)

15.08.020 General installation requirements.

A. A HUD-labeled mobile home shall be installed in compliance with the manufacturer’s installation recommendations. The recommendations must be approved by HUD. The manufacturer shall send two copies of its approved installation recommendations to the purchaser of the mobile home. The copies shall be in the home and available at the time of inspection. A mobile home not labeled by HUD may be installed in accordance with installation recommendations provided by a professional engineer or architect licensed in Washington.

B. To the extent that the installation of a mobile home is not covered by a manufacturer’s, engineer’s, or architect’s recommendations, the mobile home shall comply with the installation requirements set out in this chapter.

C. No person, firm, partnership, corporation, or other entity may install a mobile home unless he, she, or it owns the mobile home, is a licensed mobile home dealer, or is a contractor registered under Chapter 18.27 RCW. (Ord. 645 § 2, 1983)

15.08.030 Installation permits.

The owner or installer of a mobile home must obtain an installation permit from the city before it installs a mobile home on a building site. The applicant shall include with the application for the permit the permit fee set by NMC 15.08.120. A dealer may not deliver a mobile home until it has verified that the owner or the installer has obtained an installation permit for the mobile home. (Ord. 645 § 3, 1983)

15.08.040 Inspections.

A. The installer shall request an inspection after all aspects of the installation, other than installation of the foundation facia, have been completed. The city will inspect the installation within three business days after it receives the request. If the inspection is not completed within three business days, the tenant or owner may occupy the mobile home at his or her own risk. Occupancy before inspection does not imply approval.

B. The city shall approve the installation of a mobile home, and allow the mobile home to be occupied, if the installation complies with the installation requirements of this chapter and the conditions of the installation permit.

C. If the installation does not comply with the installation requirements of this chapter and the conditions of the installation permit, the city shall provide the installer with a list of corrections that the installer must make. The list of corrections shall state a date by which the corrections must be completed. The city shall reinspect the installation after the corrections are completed. If the items that require correction do not endanger the health or safety of the occupants, or substantially affect the habitability of the mobile home, the city may permit the owner of the mobile home to occupy it. (Ord. 645 § 4, 1983)

15.08.050 Disputes.

If a dispute concerning an installation requirement of this chapter arises between any person or business and the city, the dispute may be submitted to the mobile home, commercial coach, and recreational vehicle advisory board for its opinion as to the proper interpretation of the requirement. (Ord. 645 § 5, 1983)

15.08.060 Building site preparation.

A mobile home may not be installed at a building site unless the ground at the site has adequate compaction and load-bearing ability to meet the requirements of NMC 15.08.070. The installer or, if the building site is in a mobile home park, the park owner must ensure that the ground on which a mobile home is to be installed has been improved as necessary to provide a proper base for the mobile home and that the area beneath the mobile home has adequate drainage. (Ord. 645 § 6, 1983)

15.08.070 Foundation system footings.

A. Footings shall be constructed of:

1. Solid concrete or an approved alternate that is at least three and one-half inches thick by 16 inches square; or

2. Two eight-inch by 16-inch by four-inch solid concrete blocks that are laid with their joint parallel to the main frame longitudinal member.

B. Footings shall be:

1. Evenly bedded and leveled;

2. Placed on firm, undisturbed, or compacted soil that is free of organic material;

3. Centered in a line directly under the main frame longitudinal members on both sides of a mobile home; and

4. Spaced not more than eight feet apart, and not more than two feet from the ends of the main frame. A closer spacing may be required, depending on the load-bearing capacity of the soil.

C. A mobile home with more than one section must have centerline blocking at end walls and at any other point of connection of the sections of the mobile home that are a ridgebeam bearing support. Blocking is also required at both ends of a door opening that is six feet or more wide in an exterior wall.

D. If a mobile home requires footings on its exterior perimeter, the footings shall be installed below the frost line. Footings for the main frame longitudinal members must be recessed only if frost heave is likely to occur.

E. Footings shall be constructed so that 75 percent of the area under the mobile home has at least 18 inches clearance between the bottom of the main chassis members and the ground level. The area beneath furnace cross-overs and fireplaces, however, must always have at least 18 inches clearance. At no point under the mobile home may the clearance be less than 12 inches. (Ord. 645 § 7, 1983)

15.08.080 Foundation system piers.

An installer must build and position piers and load-bearing supports or devices to distribute the required loads evenly. An installer may use manufactured piers or load-bearing supports or devices that are listed or approved for the intended use, or may build piers that comply with the following requirements. All blocks must be concrete blocks set with the cores placed vertically. A wood plate must be of hem-fir or douglas fir-larch.

A. A pier may be made of a single stack of eight-inch by eight-inch by 16-inch blocks if the blocks are not stacked more than three blocks high. A pier made of a single stack of blocks shall be installed at a right angle to the main frame longitudinal member and shall be capped with no more than two two-inch by eight-inch by 16-inch wood plates or one four-inch concrete plate.

B. A pier may be made of a double stack of eight-inch by eight-inch by 16-inch blocks if the blocks are not stacked more than five blocks high. Each row of blocks in such a pier shall be stacked at right angles to the abutting rows of blocks. The pier shall be capped with two two-inch by eight-inch by 16-inch wood or concrete plates. The pier shall be installed so that the joint between the cap plates is at right angles to the main frame longitudinal member.

C. A pier may be made with more than five rows of blocks if the stacked blocks are filled with 20,000 pounds per square inch concrete or mortar. A licensed architect or professional engineer must approve a foundation system that includes a pier that is 72 inches (nine blocks) high or higher, or in which more than 20 percent of the piers exceed 40 inches (five blocks) high. (Ord. 645 § 8, 1983)

15.08.090 Foundation system plates and shims.

An installer may fill a gap between the top of a pier and the main frame with a wood or concrete plate that is not more than two inches thick and two opposing wedge-shaped shims that are not more than two inches thick. A shim shall be at least four inches wide and six inches long. The installer shall fit the shim properly and drive it tight between the plate and the main frame to ensure that the mobile home is level and properly supported at all load-bearing points. A block or plate that abuts a wedge-shaped shim shall be solid wood plate and shims shall be of hem-fir or douglas fir-larch. (Ord. 645 § 9, 1983)

15.08.100 Foundation facia.

A mobile home shall have an approved foundation facia around its entire perimeter. The wood of the facia shall be at least three inches from the ground unless it is pressure-treated wood. Metal fasteners shall be galvanized, stainless steel, or other corrosion-resistant material. Ferrous metal members in contact with the earth, other than those that are galvanized or stainless steel, shall be coated with an asphaltic emulsion.

Under-floor areas shall be ventilated by openings in the foundation facia with a net area of not less than one square foot for each 150 square feet of under-floor area. Openings shall be located as close to corners as practical and shall provide cross ventilation. The required area of such openings shall be approximately equally distributed along the length of at least two opposite sides. They shall be covered with corrosion-resistant wire mesh with mesh openings of one-fourth inch in dimension.

Dryer vents and hot water pressure relief valves shall exhaust on the exterior of the foundation facia. The facia for each section of a mobile home shall have an opening of at least 18 inches by 24 inches, with a cover of metal or pressure-treated wood, to allow access to the crawl space. The foundation facia must be installed within 30 days after the mobile home is occupied. (Ord. 645 § 10, 1983)

15.08.110 Assembly.

A. Sections of a multiple section mobile home shall be aligned, closed, and securely fastened at the required points along the ridge beam, endwalls, and floor line. Heat ducts, electrical connections, and other fixtures and connections required between sections of a mobile home shall be properly installed. The floor of the mobile home shall be level within the tolerances given in the following table.

Tolerances may not exceed the following amounts (L equals the clear span between supports, twice the length of a cantilever):

Floor:     L/240

Roof and ceiling:     L/180

Headers, beams, girders

(vertical load):     L/180

Walls and partitions:     L/180

B. The installer shall provide adequate clearance to ensure that the cross-over heat duct does not touch the ground and is not compressed. The installer shall insulate the cross-over duct at the intersection. The installer shall insulate and seal areas of potential air leaks to ensure that the mobile home is airtight, and shall seal areas of potential water leaks with metal flashing or trim, if required, and with putty tape or with other approved caulking to ensure the mobile home is watertight.

C. The water pipe connection to the mobile home shall have a main shut-off valve. All utility connections to the mobile home shall comply with applicable city codes and ordinances. Accessory structures attached to or located next to a mobile home, such as awnings, carports, garages, porches, or steps, shall be constructed in conformance with the city building code. (Ord. 645 § 11, 1983)

15.08.120 Fees.

The permit fee for each application permit required by this chapter shall be as set forth in the current city fee schedule. (Ord. 2007 § 2, 2014)

15.08.130 Administration and enforcement.

The building inspector shall be responsible for the administration and enforcement of this chapter. (Ord. 645 § 13, 1983)