Cal. Health & Saf. Code § 17912
Rules and regulations promulgated pursuant to the provisions of this part and building standards published in the State Building Standards Code, relating to the erection or construction of buildings or structures, shall not apply to existing buildings or structures or to buildings or structures as to which construction is commenced or approved prior to the effective date of the rules, regulations, or building standards, except by act of the Legislature, but rules, regulations, and building standards relating to use, maintenance, and change of occupancy shall apply to all hotels, motels, lodginghouses, apartment houses, and dwellings, or portions thereof, and buildings and structures accessory thereto, approved for construction or constructed before or after the effective date of such rules, regulations, or building standards.
Ca. Health and Saf. Code § 17912