(a) The provisions of Section 17920.9, and the rules and regulations adopted pursuant thereto, shall be applicable to the sale, offering for sale, or use in the construction of commercial coaches and of manufactured homes and mobilehomes which are not subject to the National Manufactured Housing Construction and Safety Act of 1974 (42 U.S.C., Sec. 5401, et seq.), of any foam building system, and to any such mobilehome or commercial coach in which that system is used as a component.
(b) All manufactured homes, including mobilehomes manufactured on or after June 15, 1976, shall comply with the National Manufactured Housing Construction and Safety Act of 1974 (42 U.S.C., Sec. 5401, et seq.).