To: Board of Supervisors
From: John Kopchik, Director, Conservation and Development
Report Title: Public Hearing to consider Ordinance No. 2025-19, adopting the 2025 California Building Standard Codes
☒Recommendation of the County Administrator ☐ Recommendation of Board Committee
RECOMMENDATIONS:
1. OPEN the public hearing on Ordinance No. 2025-19, RECEIVE testimony, and CLOSE the public hearing.
2. ADOPT 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.
3. ADOPT the attached findings in support of the County’s changes, additions, and deletions to the statewide codes.
4. DIRECT the publication of the ordinance summary prepared by County Counsel and DIRECT the Clerk of the Board of Supervisors to post a certified copy of the full text of the adopted ordinance in the office of the Clerk of the Board, in accordance with Government Code section 25124(b).
5. DIRECT the Department of Conservation and Development, pursuant to Health and Safety Code section 17958.7, to send a certified copy of Ordinance No. 2025-19, the attached findings, and this Board Order to the California Department of Housing and Community Development and to the California Building Standards Commission.
6. FIND that adoption of the ordinance is exempt from the California Environmental Quality Act pursuant to CEQA Guidelines section 15061(b)(3).
7. DIRECT staff to file a Notice of Exemption with the County Clerk.
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:
o Projects that increase the total combined conditioned and unconditioned building area by 5,000 square feet or more.
o Projects that impact 5,000 square feet or more of the total combined conditioned and unconditioned building area.
o 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 2025 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.