(1) All body and frame design and construction and all plumbing, heating, and electrical systems installed in manufactured homes or recreational vehicles manufactured, sold, offered for sale, or leased in this state more than four months after May 27, 1975, and before May 1, 1998, shall comply with the standards of the state agency responsible for regulation of manufactured homes or recreational vehicles as such standards existed on the date of manufacture.

(2) All body and frame design and construction and all plumbing, heating, and electrical systems installed in manufactured homes or recreational vehicles manufactured, sold, offered for sale, or leased in this state on or after May 1, 1998, shall be at least equal to the standards adopted and approved by the commission pursuant to its rules and regulations as such standards existed on the date of manufacture. The standards pertaining to manufactured homes shall conform to the Manufactured Home Construction and Safety Standards, 24 C.F.R. § 3280, and the Manufactured Home Procedural and Enforcement Regulations, 24 C.F.R. § 3282, adopted by the United States Department of Housing and Urban Development pursuant to the National Manufactured Housing Construction and Safety Standards Act of 1974, as amended, 42 U.S.C. § 5401 et seq. Manufactured homes and recreational vehicles destined for sale outside the United States shall be exempt from such regulations if sufficient proof of such delivery is submitted to the commission for review. The standards pertaining to recreational vehicles shall (a) protect the health and safety of persons living in recreational vehicles, (b) assure reciprocity with other states that have adopted standards which protect the health and safety of persons living in recreational vehicles the purpose of which is to make uniform the law of those states which adopt them, and (c) allow variations from such uniform standards as will reduce unnecessary costs of construction or increase safety, durability, or efficiency, including energy efficiency, of the recreational vehicle without jeopardizing such reciprocity.