No residential dwelling unit within the city, including single-family residences, condominiums, apartment buildings, mobile homes, motels or hotels shall be sold or released from escrow until a smoke detector or detectors have been installed therein in conformance with the requirements of § 1210(a) of the 1979 Uniform Building Code. It shall be the responsibility of the seller of such residential property to comply, at his or her own expense, with the requirements of this section prior to such sale. (Ord. 81-9 § 1, 1981)