San Mateo County, CA Fence Regulations: Height Limits (2026)

San Mateo County Zoning Regulations Chapter 8.332 (Fences, Hedges, Walls, Height & Exceptions), formerly prior code Section 6412, governs fences in the unincorporated county. Section 8.332.010 allows fences, walls, and hedges up to 4 feet high in any front yard, and up to 6 feet in side or rear yards, provided they do not extend into a required front yard. On a corner lot, a 6-foot fence may not extend into the side yard along a side street, nor into the portion of the rear yard abutting that side street equal to the required side-yard width. To preserve visibility, the county caps fences, walls, hedges, and growth within 50 feet of intersecting street lines on a corner lot at 4 feet, and requires trees in that area to be trimmed free of branches to 7.5 feet above the curb. The county's own guidance further explains that the first 20 feet of a side property line (measured from the front yard) is limited to 4 feet, and 10 feet on a corner lot. Larger parcels (100-foot frontage in certain S districts requiring 20,000-square-foot minimum sites) may place a 6-foot fence in more of the yard. Heights are measured from the lowest adjacent natural grade. Coastal Zone parcels are subject to additional Local Coastal Program review.