CITY OF SAN MATEO
CITY OF SAN MATEO
Agenda Report
City Hall
330 W. 20th Avenue
San Mateo CA 94403
www.cityofsanmateo.org
Agenda Number: 12 Section Name: NEW BUSINESS Account Number: 26-3125 File ID: 25-10284 TO: City Council
FROM: Alex Khojikian, City Manager
PREPARED BY: Community Development Department
MEETING DATE: October 20, 2025
SUBJECT:
2025 Triennial Building Code Update — Ordinance Introduction RECOMMENDATION:
Adopt a Resolution to set forth express findings that amendments to the 2025 Building Standards Codes are reasonably necessary based on local climatic, topographical, or geological conditions; and, introduce an Ordinance to amend San Mateo Municipal Code Chapter 23 “Buildings and Construction” to adopt the 2025 Building Standards Code by reference with local amendments; amend various sections of San Mateo Municipal Code Title 23 “Buildings and Construction”; update procedural language and revise miscellaneous sections; add Chapter 23.29 “Wildland-Urban Interface Code”.
BACKGROUND:
Every three years, the CBSC (California Building Standards Commission) adopts and amends the California Building Standards Code (CBSC or State Code). The State Code includes model Administrative, Building, Residential, Electrical, Mechanical, Plumbing, Energy, Historical, Fire, Existing Building, Green Building, and Reference Standards Codes. For this code cycle, the CBSC created a new Wildland-Urban Interface (WUI) Code, which addresses the growing risk of wildfire in areas where urban development meets or intermingles with wildland vegetation. The 2025 State Code becomes effective statewide on January 1, 2026, as published, unless local jurisdictions adopt more stringent amendments in accordance with State law. Accordingly, the proposed Ordinance would amend Title 23 of the San Mateo Municipal Code, Building and Construction, to incorporate the current version of the State Code by reference with few local amendments. The last local Code Update was in 2022 and took effect on January 1, 2023. This update under consideration does not contain any additional REACH Code amendments to the Model Green or Energy Codes, which will be the subject of a future City Council meeting.
The proposed Ordinance also includes updates to Chapter 23.44 “Electric Vehicle Charging Stations” and Chapter 23.46 “Small Residential Rooftop Solar Energy Systems” to update the San Mateo Municipal Code with current state laws relating to the administration of these permit applications.
In addition, California Assembly Bill 130 (AB 130) restricts cities and counties from adopting local amendments to the California Building Standards Code applicable to residential units until June 1, 2031, with certain exceptions. These proposed local amendments are within the exceptions provided in AB 130 and California Health and Safety Code Sections 17958.5, and 17958.7. Specifically, these proposed local amendments are excepted from AB 130 because they are:
1) Substantially equivalent to changes or modifications previously filed by the City and were in effect prior to September 30, 2025;
2) Necessary as emergency standards that protect health and safety; or 3) Are modifications that relate to home hardening.
CITY OF SAN MATEO
DISCUSSION:
The Triennial Building Code adoption is like most code adoption years, as this Building Code update is essentially an amendment to reflect the most current version of the model codes, continuation of amendments adopted during previous code adoption cycles, and corrections to specific code sections. During the previous update adopted in 2022, more extensive amendments in addition to adopting the latest version of the model codes were proposed. City Council adopted these amendments to accomplish the following:
• Eliminate redundant provisions, i.e. text that essentially tracks the model codes. • Correct improper references to the model codes.
• Incorporate additional model codes that were not included in previous Building Code updates, either due to staff oversight or because those codes had not been formally adopted by the Building Standards Commission. • Incorporate by reference the Fire Code as adopted by the San Mateo Consolidated Fire District.
In addition to the required State Codes and amendments, the State also provides Model Codes that are optional and may or may not be adopted by local jurisdictions in the form of Appendices, which are recommended for adoption. A summary of the proposed local amendments to the 2025 State Code and optional Appendices are as follows:
Residential Code Amendment(s):
California Residential Code (CRC) Chapter 6 (Wall Construction) Section R602 Table R602.10.3(3) and Section R602.10.4.5 are amended to provide greater seismic design requirements by disallowing the use of poorly performing plaster, gypsum, and particle board products as bracing methods. This amendment is a continuation of an amendment adopted during the previous code adoption cycle. This amendment is also consistent with the design limitations for similar shear walls found in Table 2308.6.1 of the 2022 California Building Code.
Residential Code Appendices:
Appendix BF – Patio Covers relaxes certain provisions related to Patio Covers intended for recreational use regarding screening, glazing, light, ventilation, egress, footings, and structural design. This appendix helps streamline and expedite processing of recreational project permits not exceeding 12’ in height.
Appendix BG – Sound Transmissions relates directly to the psychological and long-term physical well-being of building occupants by mitigating the sound transmission from other spaces and between dwelling units. Adopting this appendix aligns the Residential Code with the provisions of the Building Code.
Appendix CI – Swimming Pool Safety Act reflects and aligns the Residential Code with the provisions found in CA Health and Safety Code Sections 115920 through 115929 and Building Code Section 3109. This appendix provides enhanced safety measures for swimming pools and spas in residential settings.
Building Code Amendments:
California Building Code (CBC) Chapter 15 (Roof Assemblies) Section 1505.1 is amended to provide greater fire resistance of roof coverings (minimum Class “B”) and by disallowing the lower “Class C” roof covering in all construction types. This amendment is a continuation of an amendment adopted during the previous code adoption cycles.
CBC Chapter 17 (Special Inspections) Section 1705.3 is amended to enhance regional consistency in the application and enforcement of the Building Code regarding the requirement of special inspections for isolated spread footings. This amendment is a continuation of an amendment adopted during the previous code adoption cycle.
CBC Chapter 23 (Wood) Section 2308 Table 2308.6.1 is amended to provide greater seismic design requirements by disallowing the use of poorly performing plaster, gypsum, and particle board products as bracing methods. This amendment is a continuation of an amendment adopted during the previous code adoption cycle.
CBC Section 3109 (Swimming Pools, Spas, and Hot Tubs) is adopted and includes amendments adopted during the previous code adoption cycle.
CITY OF SAN MATEO
CBC Section 3110 (Automatic Vehicular Gates) is adopted and amended to provide additional safety measures that reduce the risk of death or injury that may result from gates detaching from supporting hardware.
Building Code Appendix:
Appendix G (Flood Resistant Construction) is needed to ensure local compliance with Federal Emergency Management Agency (FEMA) requirements concerning construction in flood plains. The City’s Public Works Department completed the North Shoreview Levee and Pump Station Improvement Project, by raising the City’s levee and thereby removing most properties within the City’s North Shoreview and North Central neighborhoods from the flood plain. The City is required to ensure proper flood protection for the small number of properties that remain within a flood zone.
Appendix G requires construction features such as raised floors and drainage vents that would accomplish this.
Wildland-Urban Interface Code:
The newly created Wildland-Urban Interface (WUI) Code addresses the growing risk of wildfire in areas where urban development meets or intermingles with wildland vegetation. Its purpose is to establish consistent construction and defensible space standards that enhance community resilience and reduce wildfire loss.
The new California WUI Code consolidates provisions that were previously scattered across multiple codes, including:
California Residential Code (CRC): Requirements for ignition-resistant construction, such as roofing, exterior walls, and vents.
California Building Code (CBC): Structural fire safety, materials testing, and performance-based design criteria. California Fire Code (CFC): Operational standards for defensible space, access, water supply, and vegetation management.
By assembling these elements into a single, dedicated Part 7 of Title 24, the State created a streamlined and comprehensive framework. This makes it easier for jurisdictions, builders, and property owners to understand and apply the requirements, while also ensuring alignment with fire science and best practices identified through Cal Fire, the Office of the State Fire Marshal, and national model codes.
The WUI is adopted, and amended from time to time, by the San Mateo Consolidated Fire Department, and is adopted as the rules, regulations, and standards of the City.
To adopt local amendments to the 2025 Building Standards Code, California Health and Safety Code Sections 17922, 17958, 17958.5, 17958.7, and 18941.5, the City is required to make express findings that the local amendments are reasonably necessary based on local climatic, geological, or topographical conditions. These express findings are located in a proposed resolution (Attachment 1) and are required to be adopted concurrently with the proposed ordinance.
BUDGET IMPACT:
The processing of this ordinance and associated staff training are fully funded in the Community Development Department’s annual operating budget, utilizing the Construction Services Fund (Fund 230), and does not impact the City’s General Fund.
ENVIRONMENTAL DETERMINATION:
This introduction of an ordinance adopting by reference the 2025 Building Standard Codes with local amendments is not a project subject to CEQA, because it is an organizational or administrative activity that will not result in direct or indirect physical changes in the environment. (CEQA Guidelines Section 15378(b)(5))
NOTICE PROVIDED
All meeting noticing requirements were met, including the publishing of a public notice in a newspaper of general circulation once per week for two successive weeks in advance of the public meeting in accordance with Government Code Section 6066.
CITY OF SAN MATEO
ATTACHMENTS
Att 1 – Proposed Resolution
Att 2 – Proposed Ordinance
Att 3 – Proposed Ordinance (Track Changes)
STAFF CONTACT
Michael Titsworth, Deputy Director and Building Official [email protected]
(650) 522-7195