(a) Where the space beneath an MH-unit is enclosed, there shall be provided a removable access panel opening a minimum of eighteen (18) inches by twenty-four (24) inches unobstructed by pipes, ducts, or other equipment that may impede access. The access panel shall not be fastened by any means requiring the use of a special tool or device to remove the panel.

(b) Cross ventilation shall be provided by openings having a net area of not less than one and one-half (1 ½ ) square feet for each twenty-five (25) linear feet of the MH-unit and including all skirted structures such as porches. The openings shall be provided on at least the two (2) opposite sides along the greatest length of the unit and shall be installed as close to all the corners as practicable.

(c) When wood siding or equivalent home siding products are used as skirting material, the installation shall comply with the siding manufacturer installation instructions. Where siding manufacturer installation instructions are not available, the installation shall conform to the provisions of the California Residential Code. All wood products used in skirting construction located closer than six (6) inches to earth shall be treated wood or wood of natural resistance to decay. Where located on concrete slabs placed on earth, wood shall be treated wood or wood of natural resistance to decay.

(d) Where manufacturer installation instructions require the use of a ground vapor barrier under the MH-unit, skirting shall be provided in accordance with this section.

(e) When skirting is installed on an MH-unit or accessory structure in a floodplain, as designated by the local floodplain management agency, the skirting shall be either: