(A) The installation of any manufactured home structure shall require the approval of the Building Inspector during all phases of the installation.
(B) All manufactured homes will be installed in compliance with the following standards.
(1) Foundations system footings.
(a) Footings shall be constructed of either a solid concrete or an approved alternative that is at least three ad one-half inches thick by 16 inches square; or two, four- by eight-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 manufactured 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 manufactured 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 manufactured home that are a ridge beam 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 manufactured 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% of the area under the manufactured home has at least 18 inches of clearance between the bottom of the main chassis members and the ground level. The area beneath furnace cross-over and fireplaces, however, must always have at least 18 inches of clearance. At no point under the manufactured home may clearance be less than 12 inches.
(2) Foundation system piers.
(a) 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.
(b) A pier may be made of a single stack of eight-inch by eight-inch blocks if the blocks are not stacked more than three blocks high. A pier made of single stack of blocks shall be installed at right angles to the main frame longitudinal member and shall be capped with no more than two, two-inch by eight-inch by 16-inch wood blocks or one four-inch by eight-inch by 16-inch concrete block.
(c) A pier may be made of a double stack of eight-inch by eight 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. A wood block must be of hem-fir, Douglas fir or spruce pine fir. The pier shall be capped with two, two-inch by eight-inch by 16-inch wood or concrete blocks. The pier shall be installed so that the joint between the cap blocks is at right angles to the main frame longitudinal member.
(d) A pier may be made with more than five rows of blocks if the stacked blocks are filled with 2,000 psi concrete or mortar. A licensed architect or professional engineer must approve a foundation system that includes a pier that is higher than 72 inches (nine blocks) high, or in which more than 20% of the piers exceed 40 inches (five blocks) high.
(e) All blocks shall be set with the cores placed vertically.
(3) Foundation system plates and shims. An installer may fill a gap between the top of a pier and the main frame with a wood plate that is not more than two inches thick and two opposing wedge-shaped shims that are not more than two inches thick. Wood plates and shims must be of hem-fir, Douglas fir or spruce pine fir. 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 wood plate or pier and the main frame to ensure that the manufactured home is level and properly supported at all load-bearing points. A block that abuts a wedge-shaped shim must be solid.
(4) Foundation fascia.
(a) A manufactured home shall have an approved foundation fascia around its entire perimeter. The wood of the fascia 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.
(b) A manufactured home that is installed on a non-recessed site and that has a metal foundation fascia shall have ventilation openings with a net area of at least one and one-half square inches per linear foot. A manufactured home that has been installed on a recessed site or that has a foundation fascia that is not made of metal shall have ventilation openings in the foundation fascia with a net area of at least one and one-half square feet for each 25 linear feet of fascia. The openings shall be designed to provide cross ventilation on at least two approximately opposite sides of the manufactured home. The installer shall locate the openings as close to the corners of the manufactured home as practical and shall cover the openings with corrosion-resistant wire or louvers.
(c) Dryer vents and hot water tank pressure relief valves shall exhaust on the exterior of the foundation fascia. The fascia for each section of manufactured home shall have an opening of at least 18 by 24 inches, with cover of metal or pressure treated wood, to allow access to the crawl space. The foundation fascia must be installed within 30 days after the manufactured home is occupied.
(5) Assembly.
(a) Sections of multiple section manufactured homes shall be aligned, close and securely fastened at the required points along the ridge beam, end walls and floor line. Heat ducts, electrical connections, and other fixtures and connections required between sections of a manufactured home shall be properly installed. The floor of the manufactured 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) | |
Floor | L/240 inches |
Headers, beams and girders (vertical load) | L/180 inches |
Roof and ceiling | L/180 inches |
Walls and partitions | L/180 inches |
(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 intersections. The installer shall insulate and seal areas of potential air leaks to ensure that the manufactured home is air-tight and shall seal areas of potential water leaks with metal flashing or trim, if required, and with putty, tape or other approved caulking to ensure the manufactured home is watertight.
(c) The water pipe connection to the manufactured home shall have a main shut-off valve approved by the Public Works Department. In all other respects, utility connections to the manufactured home, including water, sewer, electricity and gas, shall comply with the same standards as housing of conventional construction. Accessory structures attached to or located next to a manufactured home, such as awnings, carports, garages, porches or steps, shall be constructed in conformance with the same construction standards as applies to conventional housing.
(Prior Code, § 11.01.060.070) (Ord. 2021-15, passed 12-20-2021)