Section 1334 - MH-Unit Support Piers and Footings(a) Load bearing piers shall be constructed of rust resistant materials or treated to resist rust. The required load bearing capacity of individual support piers and their footings shall be calculated at not less than a combined live and dead load of seventy-five (75) psf based on roof live and dead load of twenty-five (25) psf and floor live and dead load of fifty (50) psf of the MH-unit.(b) Load bearing piers, other than concrete block piers, shall be tested to determine the safe operating load. The tests shall be conducted by testing agencies approved by the department. Testing agencies shall provide a pier testing report to the department upon completion, regardless of the testing results. A unique number provided by the testing agency shall identify each test report. The following testing procedures shall be used:(1) A compression test shall be performed on three (3) piers of the same height and construction, selected randomly at the pier manufacturing facility by a representative of the testing agency.(A) The compression test shall be performed on piers with all required design assemblies installed, such as adjustable tops, clamps, securement devices or similar assemblies.(B) The selected piers shall be subjected to the compression test with each pier, fully assembled as will be installed, placed squarely on a firm base, and tested to its failure point. The compression test shall be measured in psf. Support pier failure will be established when the support bends, cracks, buckles or deflects to an unsafe level as determined by the approved testing agency.(C) The safe operating load of a support pier is one-third ( 1/3) the average of the three (3) failure tests.(2) When piers differ in height or construction, design tests and evaluations must be performed on each type of pier.(c) Tested load bearing piers other than concrete block piers shall be listed and labeled as follows: (1) Listing of piers shall be conducted by listing agencies approved by the department. (A) The listing agency shall conduct manufacturer facility audits and prepare finding reports not less than once per year. The audit report will include, at a minimum: (i) the review of pier construction for compliance with manufactured designs as approved by the testing agency,(ii) the materials used in its construction including type, size, and weight,(iii) the manufacturers quality control program, if applicable, and(iv) the label application and label control process.(B) The listing agency shall provide an annual report to the department of its approval and audit findings.(2) Pier supports shall display a legible permanent label of approval, visible when the pier support is installed. The label shall contain the following information: (C) Listing number issued by the listing agency,(D) Testing agency's approved operating load, and(E) Testing agency's test report number.(d) Individual load bearing footings may be placed on the surface of the ground, and shall be placed level on cleared, firm, undisturbed soil or compacted fill. Where unusual soil conditions exist, as determined by the enforcement agency, footings shall be designed to compensate for such conditions. The allowable loading on the soil shall not exceed one thousand five-hundred (1,500) psf unless data to substantiate the use of higher values is approved by the enforcement agency.(e) Footings shall be adequate in size to withstand the tributary live and dead loads of the MH-unit and any concentrated loads. The length to width ratio of the footing shall not exceed two and one-half (2.5) to one (1). Individual footings for load bearing supports or devices shall consist of one of the following:
(1) Pressure treated lumber which meets the following requirements:(A) Not less than two (2) -inch nominal thickness with a minimum of twenty-five (25) percent of the individual footings identified by an approved listing agency, as being pressure treated for ground contact.(B) Knots. Well spaced knots of any quality are permitted in sizes not to exceed the following or equivalent displacement: Nom. Width | Any Location | Holes (Any Cause) | |
| 6" | 2 3/8" | 1 1/2" | |
| 8" | 3" | 2" | One Hole or |
| 10" | 3 3/4" | 2 1/2" | Equivalent |
| 12" | 4 1/4" | 3" | Per Piece |
| 14" | 4 5/8" | 3 1/2" | |
(C) Splits. In no case exceed one-sixth ( 1/6) the length of the piece.(D) Honeycomb or Peck. Limited to small spots or streaks of firm honeycomb or peck equivalent in size to holes listed in (B) above.(2) Precast or poured in place concrete footings not less than three and one-half (3 1/2) inches in thickness. The concrete shall have a minimum twenty-eight (28)-day compressive strength of not less than two thousand five hundred (2500) psi.(3) Other material, approved by the department, providing equivalent load bearing capacity and resistance to decay.(f) Individual load bearing piers or devices and footings shall be designed and constructed with sufficient rigidity and bearing area to evenly distribute the loads carried over one-third ( 1/3) the area of the footings as measured from the center of the footing. When two (2) or more two (2)-inch nominal wood pads placed side-by-side on the ground are used as a pier footing, a single wood cross pad must be installed on top of the ground contact pads at a ninety (90)-degree angle so as to place the directional wood grains opposing to each other. The cross pad must be of a length to cover each ground contact pad and be of two (2) inch nominal thickness. Footings shall be constructed of sufficient rigidity to evenly distribute the loads carried to the ground without bowing or splitting.(g) When multiple wood footings are stacked, they shall be secured together with corrosion resistant fasteners at all four (4) corners of the pad which will penetrate at least eighty (80) percent of the base pad to prevent shifting.(h) Individual load bearing piers, which do not include the footing as defined in section 1002 of this chapter, located under the MH-unit's chassis shall not exceed thirty-six (36) inches in height.(i) When more than one-quarter ( 1/4) of the area of the MH-unit is supported at a height of three (3) feet or more as measured between each unit's chassis and the ground, the MH-unit shall be installed on a foundation system in accordance with sections 18551 (a) or (b) of the Health and Safety Code.(j) No portion of the support system above the ground shall extend beyond the vertical plane of the side or end wall of the MH-unit that would restrict or inhibit installation of skirting.Cal. Code Regs. Tit. 25, § 1334
1. Amendment of subsection (a) filed 8-22-85; effective upon filing pursuant to Government Code Section 11346.2(d) (Register 85, No. 36).
2. Amendment of section heading and section filed 7-6-2004; operative 7-6-2004 pursuant to Government Code section 11343.4 (Register 2004, No. 28).
3. Amendment of subsections (a), (d) and (i) filed 2-18-2011; operative 2-18-2011 pursuant to Government Code section 11343.4 (Register 2011, No. 7). Note: Authority cited: Sections 18300 and 18613, Health and Safety Code. Reference: Sections 18300 and 18613, Health and Safety Code.
1. Amendment of subsection (a) filed 8-22-85; effective upon filing pursuant to Government Code Section 11346.2(d) (Register 85, No. 36).
2. Amendment of section heading and section filed 7-6-2004; operative 7-6-2004 pursuant to Government Code section 11343.4 (Register 2004, No. 28).
3. Amendment of subsections (a), (d) and (i) filed 2-18-2011; operative 2-18-2011 pursuant to Government Code section 11343.4 (Register 2011, No. 7).