California Building Permit Guides

California builds on a single statewide code — the California Building Standards Code, known as Title 24 — adopted on a three-year cycle by the California Building Standards Commission. The 2025 edition took effect on 1 January 2026, and it includes a new California Wildland-Urban Interface Code (Part 7), which replaces the former wildfire chapters of the building and residential codes. The editions that apply to a project are those in effect when the permit application is submitted (Health and Safety Code 18938.5).

Cities and counties enforce Title 24 and may adopt local amendments, but an amendment must be equal to or more restrictive than the state code, justified by express findings of local climatic, geological or topographical conditions, and filed with the Commission (Health and Safety Code 17958.5, 17958.7, 18941.5). From 1 October 2025 to 1 June 2031, cities and counties may not adopt new amendments that apply to residential units, apart from limited exceptions such as amendments already in effect on 30 September 2025 and wildfire home-hardening rules (Health and Safety Code 17958.5(c)). So the first question on any California project is which authority has jurisdiction — the city on incorporated parcels, the county in unincorporated territory — and what local amendments it has on file.

California licenses contractors statewide through the Contractors State License Board (CSLB). Its classifications are Class A (general engineering), Class B (general building), Class B-2 (residential remodeling) and the Class C specialties for individual trades, and a contractor must hold the classification that matches the work. A licence is required for work of $1,000 or more in combined labour and materials, and for any smaller job that needs a building permit (Business and Professions Code 7048). Owner-builders may pull permits for their own property under Business and Professions Code 7044.

Trade permits are separate from the building permit. Each trade follows its own part of Title 24 — the California Electrical, Plumbing and Mechanical Codes — and the work is done by a contractor with the matching licence (for example C-10 electrical, C-36 plumbing or C-20 HVAC), by a Class B general contractor where allowed, or by an owner-builder.