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

Contra Costa County's 2025 California Fire Code amendments, adopted by Ordinance No. 1 requiring an automatic sprinkler system throughout any existing Group R-3 dwelling undergoing a substantial addition or substantial alteration. 1: a substantial addition adds new floor area exceeding fifty percent of the existing structure's gross floor area and brings the combined total to 5,000 square feet or more, while a substantial alteration removes or replaces fifty percent or more of the linear length of an interior or exterior wall, plus fifty percent of the roof, within a single year.

1 for compliance. 27 requires plans to be submitted to the fire code official for any construction, substantial alteration, or addition needing a building permit; the only carve-out is a non-sprinklered Group R-3 home where the work does not itself rise to a substantial addition or alteration. The rule applies wherever the Contra Costa County Fire Protection District or the Crockett-Carquinez Fire Protection District has jurisdiction over unincorporated territory, and plan review and inspection are handled by the fire code official. Homeowners planning a major remodel or room addition should confirm square footage and wall-replacement scope against these thresholds early, since crossing either one converts an ordinary remodel permit into one that also requires a full residential sprinkler retrofit.