Oklahoma Administrative Code
Title 765 - Oklahoma Used Motor Vehicle, Dismantler, and Manufactured Housing Commission
Chapter 37 - Manufactured Home Installers
Subchapter 7 - Installation Standards
Section 765:37-7-3 - Support Systems

(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.

(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.

(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.

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

(2) Previously occupied (used) manufactured homes.