California Code, Health and Safety Code - HSC § 19958

The building department of every city, county, or city and county shall enforce this part within the territorial area of its city, county, or city and county. The responsibility for enforcing Chapter 7 (commencing with Section 4450) of Division 5 of Title 1 of the Government Code in its application under this part shall be by such building department within the territorial area of its city, county, or city and county.

“Building department” means the department, bureau, or officer charged with the enforcement of laws or ordinances regulating the erection or construction, or both the erection and construction, of buildings.