California mechanical, plumbing, fuel gas & energy codes
California adopts one statewide code, Title 24 (the California Building Standards Code), every three years. The 2025 edition took effect January 1, 2026. Local jurisdictions may adopt stricter amendments if they make climatic, geographic or topographic findings.
Quick answer: California currently uses the 2024 UMC for mechanical work and the 2024 UPC for plumbing (see sources and dates below). A2L status: Allowed: model-code A2L provisions adopted
Adopted codes
Mechanical
2024
UMC
- Adopted as
- 2025 California Mechanical Code (Title 24, Part 4)
- Effective
- 2026-01-01
- Source
- CBSC – 2025 Title 24 California Code Changes
- Last checked
- 2026-10-27 verified
- Notes
- 2025 Title 24 published July 1, 2025, effective Jan 1, 2026.
Plumbing
2024
UPC
- Adopted as
- 2025 California Plumbing Code (Title 24, Part 5)
- Effective
- 2026-01-01
- Source
- IAPMO – 2025 California Plumbing Code
- Last checked
- 2026-10-27 verified
Fuel Gas
unverified
Fuel gas piping is covered in the California Plumbing Code
- Adopted as
- No separate state fuel gas code
- Effective
- unverified
- Source
- CBSC – Title 24 parts list
- Last checked
- 2026-10-29 unverified
- Notes
- Title 24 has no separate fuel gas part. The 2025 California Plumbing Code (Part 5, effective Jan 1, 2026) contains a Fuel Gas Piping chapter according to publisher and code-library listings, but we have not confirmed this on an official CBSC page yet.
Energy
2025
State-specific (DOE equivalent: 2024 IECC / 90.1-2022)
- Adopted as
- 2025 Building Energy Efficiency Standards (Title 24, Part 6)
- Effective
- 2026-01-01
- Source
- U.S. DOE Building Energy Codes Program – California
- Last checked
- 2026-10-27 verified
A2L refrigerants in California
The 2025 CMC repeals the A2L amendments California adopted early in the 2022 Supplements and adopts the model-code Chapter 11, including Table 1102.3 and the A2L/B2L provisions.
Source: https://www.dgs.ca.gov/BSC/Resources/2025-Title-24-California-Code-Changes · Last checked 2026-10-27 verified
Local amendments & things to watch
- Local jurisdictions may amend Title 24 to be more stringent, based on findings of climatic, geographic, topographical or environmental conditions. verified source