California Code, Health and Safety Code - HSC § 129985

(a) Whenever it is necessary to make an inspection to enforce any of the provisions of this chapter or whenever the department or its authorized representatives has reasonable cause to believe that there exists in any building or upon any premises any condition or a violation of any applicable building standards that makes the building or premises unsafe, dangerous, or hazardous, the department or its authorized representatives may enter the building or premises at any reasonable time to make an inspection or to perform any authorized duty. Prior to an entry authorized by this section, the authorized representatives of the department shall first present proper identification and credentials and request entry. In the event that the building or premises are unoccupied, there shall be a reasonable effort made to locate the owner or other person or persons having control or charge of the building or premises in order to request an entry. If a request for entry is refused, the department or its authorized representatives shall have recourse to any remedy prescribed by law to secure entry.

(b) Whenever the owner, occupant, or other person having control or charge of the building or premises is presented with a proper inspection warrant or other authorization prescribed by law to secure entry and a request for entry is made, the owner, occupant, or other person having control or charge of the building or premises shall promptly permit the entry of the authorized representatives of the department for the purpose of inspection and examination authorized by this chapter.