To: Board of Supervisors
From: John Kopchik, Director, Conservation and Development
Report Title: Introduce Ordinance No. 2025-19, adopting the 2025 California Building Standard Codes
☒Recommendation of the County Administrator ☐ Recommendation of Board Committee

RECOMMENDATIONS:
1. INTRODUCE Ordinance No. 2025-19, adopting the 2025 California Building Code, the 2025 California Residential Code, the 2025 Electrical Code, the 2025 Mechanical Code, the 2025 Plumbing Code, the 2025 Energy Code, the 2025 Historical Building Code, the 2025 Existing Building Code, and the 2025 California Green Building Standards Code with changes, additions, and deletions, WAIVE reading, and FIX November 4, 2025 at 9:30 a.m. for a public hearing to consider adoption of the ordinance and adoption of findings of local conditions to justify construction standards stricter than those imposed by Health and Safety Code section 19180 et seq.
2. DIRECT the Clerk of the Board to publish notice of the hearing pursuant to Government Code section 6066.
3. AUTHORIZE the preparation of an ordinance summary by County Counsel and the publication of the summary in accordance with Government Code section 25124, and DIRECT the Clerk of the Board of Supervisors to post a copy of the full text of the proposed ordinance in the office of the Clerk of the Board.
FISCAL IMPACT:
None
BACKGROUND:
The California Building Standards Commission has adopted the 2025 California Building Standards Code (CBSC), replacing the 2022 CBSC. The CBSC includes the California Building, Residential, Electrical, Mechanical, Plumbing, Energy, Historical Building, and Existing Building and Green Building Standards Codes. These statewide codes will be effective January 1, 2026. The Department of Conservation and Development is responsible for enforcing the CBSC within the unincorporated area of Contra Costa County.
Although these codes apply statewide, Health and Safety Code sections 17958.5 and 18941.5 authorize a local jurisdiction to modify or change these codes and establish more restrictive building standards if the local jurisdiction finds that the changes and modifications are reasonably necessary because of local climatic, geological, topographical, or environmental conditions. The attached proposed ordinance would adopt the statewide codes and amend them to address local conditions.
Recent changes to State law have placed additional restrictions on the authority of local jurisdictions to amend the CBSC as it relates to the construction of new residential housing units. State budget legislation (Assembly Bill 130) adopted at the end of June 2025, includes changes to the Health and Safety Code that limit the authority of local jurisdictions to adopt building code amendments related to the construction of new housing, except through several narrowly defined exceptions. These exceptions include amendments that are the same or substantially equivalent to amendments already adopted by the local jurisdiction and in effect as of September 30, 2025, and amendments that relate to home hardening for protection against fire risks. These changes to local authority will remain in effect from October 1, 2025, until June 1, 2031. Accordingly, the County may continue its current code amendments into the new code cycle, but is restricted in its authority to adopt new code amendments to the 2025 CBSC that would affect residential construction. Local jurisdictions retain broader discretion to adopt code amendments related to non-residential construction, subject to making the required findings.
The proposed Ordinance No. 2025-19 amends the statewide codes due to local climatic, geographical, topographical, and environmental conditions. These conditions are described in the attached Findings. The following are the substantive changes to the 2025 California Building Standards Code:
Modifications to the 2025 California Building Code
• Require the installation of a hard-wired smoke detector in existing flat roof buildings when a pitched roof is added on top of the existing flat roof, and the solid sheathing of the flat roof is not removed.
• Require more reinforcing in some building foundations to better withstand seismic forces found in this region of California.
Modifications to the 2025 California Residential Code
• Prohibit the use of gypsum wallboard as seismic bracing.
• Restrict the use of Portland Cement Plaster as seismic bracing to single-story one- and two-family dwellings and accessory structures.
Modifications to the 2025 California Green Building Standards Code
• Require that at least 10 percent of the total number of parking spaces for new multi-family residential and new non-residential developments be equipped with fully operational electric vehicle charging equipment. This is consistent with the County’s existing code amendments for electric vehicle charging. Although statewide code requirements for electric vehicle charging have increased in the 2025 code cycle, the County’s existing local code amendments are still necessary to ensure that current standards for electric vehicle charging are maintained.
• Apply construction waste management requirements in the statewide code to certain projects for existing residential buildings, including: Projects that increase the total combined conditioned and unconditioned building area by 5,000 square feet or more. Projects that impact 5,000 square feet or more of the total combined conditioned and unconditioned building area. Demolition projects when a demolition permit is required, except demolition projects that are necessary to abate a public nuisance. Delete the exception from construction waste management requirements for projects solely based on their isolated location from diversion facilities. Require measuring and documentation of all generated debris to ensure that at least 65% is diverted from landfills.
Modifications to the 2025 California Existing Building Code
The amendments to the 2022 California Existing Building Code are not substantive in nature and are limited to administrative provisions for the use and enforcement of this Code and to be consistent with the administrative provisions of the other statewide codes as amended.
Local amendments to the 2022 California Energy Code adopted by the Board in 2024 increasing the energy efficiency standards beyond the minimum requirements in the statewide code are not included in this code adoption ordinance because the energy efficiency standards in the new 2025 California Energy Code have significantly increased and now exceed the County’s local amendments. The County’s current local amendments will no longer be necessary after January 1, 2026 because they will be exceeded by the statewide requirements.
CONSEQUENCE OF NEGATIVE ACTION:
If the proposed ordinance is not approved, the County will not adopt the 2025 California Building Standards Code as amended by Ordinance No. 2025-19.