San Mateo County, CA Swimming Pools & Spas: Fencing Requirements (2026)

San Mateo County's published pool and fence materials do not set local pool-barrier dimensions; instead the County adopts the California Building Standards Codes (Title 10) and barrier safety is governed by the state Swimming Pool Safety Act, California Health & Safety Code sections 115920-115929. Under HSC 115923, when an enclosure is used as a drowning-prevention feature it must be a minimum of 60 inches in height; the maximum vertical clearance between the ground and the bottom of the enclosure must not exceed 2 inches; gaps or voids may not allow passage of a sphere four inches or greater in diameter; and the barrier must have no protrusions, cavities or other features that would serve as handholds or footholds allowing a child five years old or younger to climb over it. Access gates must open away from the swimming pool and be self-closing with a self-latching device, with the release mechanism placed no lower than 60 inches above the ground. Note this is separate from the County's general residential fence rule (front yards limited to 4 feet, side and rear yards to 6 feet), so a code-compliant pool barrier of 60 inches may require checking with Planning and Building, and tall barriers can trigger a Fence Height Exception. Removable mesh fencing meeting ASTM F2286 with a self-closing, self-latching, key-lockable gate is also recognized by state law.