Special Notice / Hearing: 10-day Notice_
Vote Required: Majority
To: Honorable Board of Supervisors
From: Steve Monowitz, Director of Planning and Building Department
Subject: Introduction of the 2025 Edition of the California Building Standards Code and New Title 10 (Building Regulations) of the San Mateo County Ordinance Code
RECOMMENDATION:
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Recommendation:
A) Open public hearing
B) Close public hearing
C) Find that adoption of the ordinance is exempt from the California Environmental Quality Act (CEQA) pursuant to CEQA Guidelines sections 15308 and 15061(b)(3); and
D) Introduction of an ordinance: (1) repealing Title 10 (Building Regulations) of the San Mateo County Ordinance Code; and (2) adopting a new Title 10 (Building Regulations), adopting by reference the 2025 edition of the California Building Standards Code (Title 24, Parts 1 through 12) and the 2024 International Property Maintenance Code, including local amendments and waive reading of the ordinance in its entirety.
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BACKGROUND:
Proposal: The Planning and Building Department (Department) proposes the adoption of the 2025 California Building Standards Code pursuant to State law, and corresponding amendments to the San Mateo County Ordinance Code, Title 10 (Building Regulations), in addition to local amendments to the California Building Standards Code to address specific concerns within unincorporated San Mateo County.
State Code Requirements: The California Building Standards Commission has adopted the 2025 California Building Standards Code based on the International Building Code (IBC), International Residential Code (IRC), International Fire Code (IFC), International Existing Building Code (IEBC), Uniform Mechanical Code (UMC), Uniform Plumbing Code (UPC), and National Electrical Code (NEC). The State adopts and publishes construction codes on three-year cycles. The International Code Council (ICC) and the International Association of Plumbing and Mechanical Officials (IAPMO) similarly develop construction and public safety codes on a triennial basis.
Local jurisdictions are generally required to enforce the regulations adopted by the State. However, the County may establish more restrictive building standards deemed reasonably necessary because of local climatic, geological or topographical conditions. The County’s local amendments must be readopted every three years in conjunction with the State’s triennial updates.
Assembly Bill (AB) 130, effective June 30, 2025, imposed a moratorium on local building standards affecting residential units from October 1, 2025 to June 1, 2031. Accordingly, local amendments affecting residential units are only permitted if one of the following conditions is met:
1. The changes or modifications are substantially equivalent to changes or modifications that were previously filed by the County and were in effect as of September 30, 2025.
2. The Building Standards Commission deems the changes or modifications necessary as emergency standards to protect health and safety.
3. The changes or modifications relate to home hardening.
4. The changes or modifications are necessary to implement a local code amendment that is adopted to align with a general plan approved on or before June 10, 2025, and that permits mixed-fuel residential construction consistent with federal law while also incentivizing all-electric construction as part of an adopted greenhouse gas emissions reduction strategy.
5. The changes are related to specified administrative practices.
The Department is proposing local standards that continue amendments adopted in the previous update cycle (2022), as permitted under exception 1, above. In order to take effect, all local amendments to the State codes must be submitted to the California Building Standards Commission.
DISCUSSION:
The proposed ordinance would adopt and incorporate by reference the 2025 California Building Standards Code into the San Mateo County Building Regulations. The California Building Standards Code is codified as Title 24 of the California Code of Regulations, and consists of the following parts, which the County will adopt by reference, as well as the specified appendices:
• Part 1: California Administrative Code
• Part 2: California Building Code & Appendices G through J and M
o Part 2.5: California Residential Code & Appendices BI, BJ, AA, CI, CJ
• Part 3: California Electrical Code & Annexes A through K
• Part 4: California Mechanical Code & Appendices B through D and F, G
• Part 5: California Plumbing Code & Appendices G through J and M
• Part 6: California Energy Code
• Part 7: California Wildland-Urban Interface Code
• Part 8: California Historical Building Code
• Part 9: California Fire Code & Appendices B, C, D, K, L, N
• Part 10: California Existing Building Code & Appendix A
• Part 11: California Green Building Standards Code
• Part 12: California Reference Code Standards
In addition to the California Building Standards Code, the County proposes to adopt by reference the latest (2024) edition of the International Property Maintenance Code.
The County’s local amendments proposed for this triennial cycle continue substantive and administrative changes adopted in prior code cycles. The adopting ordinance is provided as Attachment 1.
A. Proposed Substantive Changes and Local Amendments
A significant change from previous code cycles is the new State-adopted 2025 California Wildland-Urban Interface Code (CWUIC, Part 7 of the Building Standards Code). The CWUIC is based on the International Code version and was created by relocating chapters, sections, and language from several parts of Title 24, including the California Building Code, California Residential Code, and the California Fire Code. The CWUIC contains provisions addressing fire spread, accessibility for emergency responders, defensible space, water supply and more for buildings constructed in Fire Hazard Severity Zones as classified by the State Fire Marshal’s Office. Additionally, the CWUIC incorporates provisions from Title 14 (Natural Resources) and Title 19 (Public Safety) of the California Code of Regulations, as well as provisions from the Government Code, Health and Safety Code, and Public Resources Code.
The ordinance would also repeal the 2018 International Property Maintenance Code and adopt the updated 2024 International Property Maintenance Code. The updated version includes requirements for accessibility of occupiable spaces and storm shelters, maintenance of clothes dryer exhaust systems, and maintenance of smoke alarm and carbon monoxide detectors. The updated maintenance code also incorporates references to the International Plumbing Code to provide clarity on water heater safety and fixture requirements.
The 2025 Green Building Code revised and increased electric vehicle (EV) charging and energy efficiency requirements to a level that aligns with the County’s prior local amendments; accordingly the County will follow the State-adopted standards, and will no longer require a local amendment related to EV charging or energy efficiency.
In addition, staff conducted a careful review of prior local amendments and eliminated those that are no longer necessary because they are now reflected in the State-adopted standards. In all other instances, the ordinance proposes to re-adopt local amendments necessary to address the County’s local climatic, geological or topographical conditions. The ordinance includes findings of fact regarding these local conditions and the related need to continue the local amendments. No new local amendments are proposed as part of this adoption cycle.
B. Proposed Administrative Amendments
The administrative changes include readopting Title 10 (Building Regulations) of the San Mateo County Ordinance Code and updating code section numbers and applicable appendices. They also delete sections of the County’s Building Regulations that are redundant to code provisions.
Unlike substantive amendments to the State building codes, findings of fact are not required for the adoption of administrative amendments. These administrative provisions address matters such as permit requirements, application procedures, permit fees and term limits, and similar procedures.
The County Attorney’s Office has reviewed and approved the ordinance as to form.
Environmental Review:
Adoption of the proposed ordinance is exempt from the California Environmental Quality Act (CEQA) in accordance with CEQA Guidelines section 15308 as an action by the County for the protection of the environment, and under section 15061(b)(3) on the grounds that the proposed standards are more stringent than the State standards, there are no reasonably foreseeable adverse environmental impacts and there is no possibility that the activity in question may have a significant adverse effect on the environment.
COMMUNITY IMPACT:
Adoption of buildings codes will support the enforcement of minimum levels of health and safety within and around structures on private property.
FISCAL IMPACT:
There is no Net County Cost.