Cal. Civ. Code § 101.145

101.145 Smoke detectors.
(1) Definitions. As used in this section:
(a) “Residential building” means any public building which is used for sleeping or lodging purposes and includes any apartment house, rooming house, hotel, children’s home, community-based residential facility or dormitory but does not include a hospital or nursing home.
(b) “Sleeping area” means the area of the unit in which the bedrooms or sleeping rooms are located. Bedrooms or sleeping rooms separated by another use area such as a kitchen or living room are separate sleeping areas but bedrooms or sleeping rooms separated by a bathroom are not separate sleeping areas.
(c) “Smoke detector” means a device which detects particles or products of combustion other than heat.
(d) “Unit” means a residential building or that part of a residential building which is intended to be used as a home, residence or sleeping place by one person or by 2 or more persons maintaining a common household, to the exclusion of all others.
(2) Approval. A smoke detector required under this section shall bear an Underwriters Laboratories, Inc., listing mark or similar mark from an independent product safety certification organization.
(3) Installation and maintenance.
(a) The owner of a residential building shall install any smoke detector required under this section according to the directions and specifications of the manufacturer of the smoke detector.
(b) The owner of a residential building shall maintain any such smoke detector that is located in a common area of that residential building.
(c) The occupant of a unit in a residential building shall maintain any smoke detector in that unit, except that if an occupant who is not an owner, or a state, county, city, village or town officer, agent or employee charged under statute or municipal ordinance with powers or duties involving inspection of real or personal property, gives written notice to the owner that a smoke detector in the unit is not functional the owner shall provide, within 5 days after receipt of that notice, any maintenance necessary to make that smoke detector functional.
(4) Requirement. The owner of a residential building the initial construction of which is commenced before, on or after May 23, 1978, shall install and maintain a functional smoke detector in the basement and at the head of any stairway on each floor level of the building and shall install a functional smoke detector either in each sleeping area of each unit or elsewhere in the unit within 6 feet of each sleeping area and not in a kitchen.
(5) Penalty. Whoever violates this section shall forfeit to the state not more than $50 for each day of violation.
(6) Department inspection and orders. The department may inspect all residential buildings, except the interior of private dwellings, as may be necessary to ensure compliance with this section. The department may inspect the interior of private dwellings at the request of the owner or renter as may be necessary to ensure compliance with this section. The department may issue orders as may be necessary to ensure compliance with this section.