California Mechanical / HVAC Code: UMC 2025

California follows UMC 2025 as the basis for mechanical / hvac work. Permits and inspections are issued by the local Authority Having Jurisdiction (AHJ), which may publish additional amendments.

The 2025 CPC (effective 2026-01-01) is based on the 2024 UPC with California amendments. Local jurisdictions may amend further. (Mechanical code typically derives from the plumbing-code family.)