Marin County, CA Building Safety: Fire Sprinkler Requirements (2026)

Marin County's Fire Code amendments, adopted by Ordinance No. 3 shall be permitted in Group R-3 occupancies and shall be provided throughout all one- and two-family dwellings regardless of square footage in accordance with the California Residential Code,' and that mobile homes, manufactured homes and multi-family manufactured homes with two or more dwelling units be sprinklered under Title 25 of the California Code of Regulations. 1 requires an automatic sprinkler system in all newly constructed buildings or structures, with narrow exceptions for items like detached pool houses, workshops or private garages under 1,000 square feet built with an existing non-sprinklered single-family home, small Group B/M buildings under 1,000 square feet, and certain agricultural buildings under 2,000 square feet in an agricultural zoned district.

1 separately requires sprinklers for any 'substantial remodel' or any addition of 50% or more floor area within a 36-month period. 3 layers on installation specifics: attached garages must be sprinklered wherever the residence is sprinklered, attics in non-single-family residential occupancies must be sprinklered, and any single-family dwelling over 5,000 square feet must have a system designed to NFPA 13 or 13R. 10.