Marin Board adopts 2025 state building code with added local WUI amendments; limits treated‑wood option for new construction

The Marin County Board of Supervisors voted Nov. 4 to adopt the 2025 California Building Standards Code (Title 24) for the county and to add local amendments addressing wildfire risk in the new Wildland Urban Interface (WUI) provisions.

County building officials told the board the state’s 2025 code consolidates WUI requirements into a single code book and that local amendments were proposed to reduce fire risk by tightening allowable exterior materials and clarifying limits on repairs and replacements. Building official Erica Freeman said staff sought consistency with county fire standards and emphasized life‑safety goals.

Staff recommended removing the option to meet WUI requirements using fire‑retardant treated wood, citing maintenance and durability concerns. Several supervisors raised concerns about cost and aesthetic mismatches for existing wood‑sided homes. To address those concerns the board adopted an amendment limiting the stricter prohibition so it would apply to new construction only; remodels and repairs would be subject to the county’s established repair thresholds (triggers for full replacement when more than 50% of a facade or deck is altered).

Erica Freeman explained the county is coordinating amendments with local fire authorities and neighboring jurisdictions; the city of Novato and Southern Marin Fire have already adopted similar measures, officials said. Fire Marshal Scott Alber and staff said the goal is to reduce ember‑ignition risk and to protect both structures and firefighters.

The board adopted the ordinance as amended after staff read revised code sections into the record and a roll‑call vote.