8 county-level rules, plus city-specific rules for 4 cities in San Mateo County, California.
Verified from official government sources
In unincorporated San Mateo County, fences, walls, and hedges may not exceed 4 feet in any required front yard and 6 feet in side or rear yards. Corner-lot fences within the sight triangle are capped at 4 feet. Height is measured from the lowest adjacent natural grade.
A wooden or cyclone fence that meets the county zoning height limits generally needs no building permit. A building permit is required for fences built above a retaining wall, for masonry walls, and for taller fences. A separate Fence Height Exception is needed to exceed standard limits.
San Mateo County's zoning code sets fence heights but does not allocate cost between neighbors. Boundary-fence cost sharing is governed by California Civil Code 841, which presumes adjoining owners are equally responsible and requires 30 days' written notice before incurring shared costs.
Cal. Civil Code Sec. 841 (Good Neighbor Fence Act - Shared Boundary Fence Costs)
841. (a) Adjoining landowners shall share equally in the responsibility for maintaining the boundaries and monuments between them. (b) (1) Adjoining landowners are presumed to share an equal benefit from any fence dividing their properties and, unless otherwise agreed to by the parties in a written agreement, shall be presumed to be equally responsible for the reasonable costs of construction, ...
A building permit is required for a fence built on top of a retaining wall in unincorporated San Mateo County. Under the California Building Code, retaining walls over 4 feet high (measured from the bottom of the footing) — or any wall supporting a surcharge — also require a permit.
Unincorporated San Mateo County enforces California Swimming Pool Safety Act (H&S Code §115920-115929) and CBC Chapter 31B. Minimum 60-inch barrier, self-closing/self-latching gates, plus at least TWO additional drowning prevention features for new pools since 2018.
California Health and Safety Code § 115923 (Swimming Pool Safety Act)
115923. An enclosure shall have all of the following characteristics: (a) Any access gates through the enclosure open away from the swimming pool, and are self-closing with a self-latching device placed no lower than 60 inches above the ground. (b) A minimum height of 60 inches. (c) A maximum vertical clearance from the ground to the bottom of the enclosure of two inches. (d) Gaps or voids, if ...
Fences in unincorporated San Mateo County must comply with Chapter 8.332 height limits, corner-lot sight-distance rules, and grade-based measurement. Pool fencing, right-of-way encroachment, and Coastal Zone parcels carry additional requirements.
San Mateo County's countywide fence ordinance (Ch. 8.332) regulates fence height and placement rather than materials, and expressly recognizes wood and cyclone fencing. Some specific districts and design-review overlays restrict materials like chain link, corrugated metal, and masonry near street frontages.
Wood and cyclone (chain-link) fences are the standard, permit-exempt materials in unincorporated San Mateo County when built within height limits. Masonry fences require a building permit, and certain districts restrict materials near street frontages.
4 cities in San Mateo County have their own fence regulations rules. Each link goes to that city's dedicated page with code citations.
6 verified rules • Height Limits, Material Restrictions
7 verified rules • Height Limits, Material Restrictions
3 verified rules • Height Limits, Neighbor Fence Rules
3 verified rules • Height Limits, Neighbor Fence Rules
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