Cal. Health & Safety Code § 18613.4

(a) All manufactured homes or mobilehomes, when initially installed or subsequently reinstalled on a different lot pursuant to Section 18613, shall be installed to resist, in conjunction with vertical loads, either forces from horizontal wind pressures of 15 pounds per square foot or the design wind load of the home, whichever is greater.
(b) For the purposes of complying with subdivision (a), all manufactured homes or mobilehomes with manufacturer’s installation instructions that include requirements for tiedowns shall be installed in accordance with all of the following:
1. (1) The manufacturer’s installation instructions.
2. (2) If not included in the manufacturer’s installation instructions, a minimum of four additional tiedowns per section shall be installed to resist the same wind forces in the longitudinal direction of the manufactured home or mobilehome as the total of those forces required to be resisted in the transverse direction. No portion of the tiedown extending beyond the vertical plane of an exterior wall of the manufactured home or mobilehome shall be above the ground.
3. (3) When used, concrete or steel piers shall have mechanical connections to the home and their footing that resist separation of the supports from the home and the footing. Mechanical connections shall not require modifications to the manufactured home or mobilehome.
(c) For the purposes of complying with subdivision (a), when no manufacturer’s installation instructions are available that include requirements for tiedowns, the manufactured home or mobilehome shall be installed in accordance with both of the following:
1. (1) Department regulations, which shall include requirements for tiedowns meeting the standards in subdivision (a).
2. (2) The requirements specified in paragraphs (2) and (3) of subdivision (b).
(d) For the purposes of complying with subdivision (a), all manufactured homes or mobilehomes may be installed or reinstalled in accordance with plans and specifications signed by a licensed architect or engineer that meet the requirements of this section.
(e) Manufactured homes or mobilehomes installed before the effective date of the act that added this section that do not meet the standards in subdivision (a) and need to be reinstalled due to damage caused by wind or seismic forces shall be reinstalled to meet the requirements of subdivision (a) and paragraphs (2) and (3) of subdivision (b), if federal funds are available for grants or direct payment of the additional installation costs.
(f) Nothing in this section prohibits the use of alternative materials, installation methods, devices, et cetera, as permitted in Section 18305, as long as the forces specified in subdivision (a) and in paragraph (2) of subdivision (b) are resisted.
(g) The department shall adopt emergency regulations in accordance with Chapter 3.5 (commencing with Section 11340) of Part 1 of Division 3 of Title 2 of the Government Code in order to implement the purposes of this section.
(h) The department shall develop standards for mechanical connections for concrete block supports that connect the blocks to the manufactured homes or mobilehomes and their footing and resist the separation of the supports from the home and the footing. By the adoption of the act that adds this subdivision, it is not the intent of the Legislature that the concrete blocks used as vertical supports be required to be mechanically attached to the manufactured homes or mobilehomes and their footings.
(i) This section shall not apply to the installation of any manufactured home or mobilehome for which escrow has been opened in accordance with Section 18035 prior to the operative date of the act that adds this section.
(j) This section shall become operative 60 days after the date that the act that adds this section is chaptered.