(a) Foundations for piers shall be installed directly under the main frame or chassis of the mobile home. All grass and organic material shall be removed and the pier foundation placed on stable soil. The piers shall not be farther apart than 10 feet on centers, and the main frame, front or face of the mobile home shall not extend farther than one foot beyond the center line of the end of the piers. Each pier foundation shall consist of two concrete blocks, and each such block shall be eight inches wide, eight inches high and 16 inches long or shall be of such other material and design as approved by the secretary.

(b) Piers shall be constructed of either open cell or solid concrete blocks, each of which shall be eight inches wide, eight inches high and 16 inches long, with open cells vertical or in combination with solid concrete blocks which are two inches thick, eight inches high and 16 inches long placed above the foundation block. A wood plate which is at least one inch in actual thickness, eight inches wide and 16 inches long shall be placed on top of the pier, with weather proof wood shims, when needed, fitted and driven tightly between the wood plate and the main frame. Such shims shall not occupy more than one inch of vertical space. Piers shall be installed perpendicular to the I-beam. All piers over 30 inches in height, measured from the top of the foundation block to the I-beam, shall be double tiered with blocks interlocked and capped with a solid concrete block, which shall be four inches high, 16 inches wide and 16 inches long, and cushioned with wood blocking as required. Piers shall not exceed 48 inches in height, unless designed by a registered professional engineer or architect. Piers also may be constructed of other material and designs approved by the secretary.