SECTION 765:37-7-3. Support Systems

(a)   Footing.

(1)   The manufacturer's installation manual shall be used to determine acceptable footing materials, sizes and placement.

(2)   For previously occupied (used) manufactured homes footing pads, when used , shall consist of three 4 X 8 X 16 solid concrete blocks or a solid 4 X 16 X 16 concrete block, ABS at least a minimum of 384 square inches in size, tested to a load-bearing capacity of not less than 6,000 pounds. Footing should be installed on a soil with an allowable soil bearing pressure of at least 1,500 P.S.F. unless the site specific information requires the use of lower values based on soil classification and type. If these conditions are encountered, a professional engineer, registered architect or licensed geologist shall be consulted to determine the soil bearing pressure and footing sizes required. All organic material (i.e., grass, loose top soil, etc.) must be removed from under each foundation support. The foundation for each manufactured home shall be installed on firm undisturbed soil or fill with at least 90 percent soil compaction. Supporting information, i.e., proper soil testing, such as by a penetrometer, may be used to change the assumed P.S.F.

(b)   Piers.

(1)   Frame piers less than 36 inches high (measured from the top of the footing to the top of the cap), are permitted to be constructed of single, open, or closed cell concrete blocks 8" X 8" by 16" when the design capacity of the block is not exceeded. The frame piers must be installed so that the long sides are at right angles to the supported I-beam. The concrete blocks must be stacked with their hollow cells aligned vertically and must be positioned at right angles to the footings. Alternatively, piers up to 36 inches in height may be manufactured steel piers, provided they meet HUD standards set forth in CFR 3285.308(b), are rated, listed and labeled for the required load capacity and are installed according to the pier manufacturer's installation instructions.

(2)   All frame piers between 36 inches and 67 inches high (measured from the top of the footing to the top of the cap) and all corner piers over three blocks high must be constructed out of double, interlocked concrete blocks, when the design capacity is not exceeded.

(3)   Piers 54 inches high or less (measured from the top of the footing to the top of the cap) which are required at mate-line supports, perimeter piers, exterior door piers on sidewalls, and piers at exterior wall openings are permitted to be constructed of single open-cell or closed-cell concrete blocks, with nominal dimensions of 8" X 8" X 16", when the design capacity of the block is not exceeded. Piers in excess of 54 inches high up to 67 inches high (measured from the top of the footing to the top of the cap) which are required at mate-line supports, perimeter piers, exterior door piers on sidewalls, and piers at exterior wall openings must be constructed out of double, interlocked concrete blocks, when the design capacity of the block is not exceeded. Piers used for perimeter support must be installed with the long dimension parallel to the perimeter rail. Perimeter piers, marriage line supports, or other supports must be located on both sides of side wall exterior doors (such as entry, patio and sliding glass doors) and any other side wall or mating line opening of 48 inches or greater in width and under load-bearing porch posts, factory installed fireplaces, and fireplace stoves. In areas where the open span is greater than 10 feet, intermediate piers and footings must be placed at a maximum of 10 feet on center.

(4)   A minimum clearance of 12 inches must be maintained between the lowest member of the main frame (I-beam or channel beam) and the grade under all areas of the home.

(c)   Pier caps.

(1)   Structural loads must be evenly distributed across capped-hollow block piers.

(2)   Caps must be solid concrete or masonry and least 4 inches in nominal thickness, and hardwood lumber at least 2 inches in nominal thickness, or be corrosion protected of a minimum one half inch thick steel. All caps must be of the same length and width as the piers on which they rest. When split caps are used on double-stacked blocks, the caps must be installed with the long dimension across the joint in the blocks below. When split caps are used, double filler and double shim sets must be used.

(d)   Gaps. Any gaps that occur during installation between the bottom of the main chassis beam and foundation support system must be filled by hardwood plates not thicker than 2 inches nominal thickness. 2 inch or 4 inch nominal thickness concrete block must be used to fill in any remaining vertical gaps.

(e)   Shims. Nominal 4" X 6" X 1" shims may be used to level the home and fill any gaps between the base of the main chassis beam and the top of the pier cap. Shims must be used in pairs, and must be driven in tightly so that they do not occupy more than on inch of vertical height.

(f)   Manufactured pier heights. Manufactured pier heights must be selected so that the adjustable risers do not extend more than 2 inches when finally positioned.

(g)   Spacing.

(1)   New manufactured homes shall follow the manufacturer's installation instructions for spacing.

(2)   Previously occupied (used) manufactured homes.

(A)   Pier spacing shall be measured from center to center of piers.

(B)   For single section homes the center of end piers shall not exceed 2 feet from the frame-ends. Piers are to be placed under each longitudinal mainframe member, not to exceed 6 feet on-center. The frame piers must be installed so that the long sides are at right angles or perpendicular to the main frame member. Side wall openings 48 inches or wider, porch transition, sliding glass doors, all exterior side doors on side walls must have perimeter piers, installed with the long dimension parallel to the perimeter rail or be supported by additional outriggers or floor joists, or by a 4 X 4 wood timber supporting a minimum of two joists under both sides of the opening.

(C)   For multi-section homes the center of end piers shall not exceed 2 feet from the frame-ends. Piers are to be placed under each longitudinal mainframe member at a spacing, not to exceed 6 feet on-center. The frame piers must be installed so that the long sides are at right angles or perpendicular to the main frame member. Side wall openings 48 inches or wider, porch transition, sliding glass doors, all exterior side doors on side walls must have perimeter piers, installed with the long dimension parallel to the perimeter rail or be supported by additional outriggers or floor joists, or by a 4 X 4 wood timber supporting a minimum of two joists, under both sides of the opening.

[Source: Added at 18 Ok Reg 2904, eff 6-25-01; Amended at 30 Ok Reg 1875, eff 7-11-13; Amended at 32 Ok Reg 1429, eff 8-27-15; Amended at 36 Ok Reg 1068, eff 7-25-19]