San Mateo County, CA Fence Regulations: Fence Requirements (2026)

Beyond raw height, San Mateo County imposes several placement and safety requirements on fences. Section 8.332.010 of the Zoning Regulations limits fences within 50 feet of intersecting street lines on a corner lot to 4 feet to maintain driver and pedestrian sight distance; the county may require a sight-distance study by a civil engineer for over-height front-yard fences on corner lots. Trees within 50 feet of intersecting street lines must be trimmed free of branches to 7.5 feet above the curb. Fences are measured from the lowest adjacent natural grade. Where a fence abuts or sits in the public right-of-way, an encroachment permit from Public Works is required, and locating the true property line may require a boundary survey. Coastal Zone parcels are not eligible for the standard Fence Height Exception and are subject to the Local Coastal Program, which may add design and resource-protection conditions. Swimming-pool enclosure fencing is separately governed by state pool-safety requirements adopted through the building code. The county also reviews fences for compatibility with neighborhood design under General Plan Policy 4.14 when an exception is sought. Because the combining 'S' (site) district and Design Review or Coastal overlays can add requirements, applicants should confirm parcel-specific rules with the Planning and Building Department before building.