San Mateo County, CA Building Setbacks & Zoning: Lot Coverage Limits (2026)
Key Facts
- Max coverage
- 50% of parcel
- Applies to
- S-50 district, North Fair Oaks
- Counts toward cap
- Patios/decks 18" or higher
- Base zoning
- R-2 / R-3 parcels
Summary
In the unincorporated North Fair Oaks S-50 combining district, buildings, accessory structures and raised patios or decks together cannot cover more than 50% of the lot.
The maximum building site coverage area ratio shall be .50 (50%) and shall include all: (1) buildings, (2) accessory buildings, and (3) structures such as patios, decks, balconies, and other similar uses which are 18 inches or more above the ground.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 47).
Full Breakdown
San Mateo County's S-50 combining district applies to two-family (R-2) and multiple-family (R-3) parcels in unincorporated North Fair Oaks. Zoning Regulations Section 8.158.070 caps building site coverage at .50 (50%) of the parcel, counting all buildings, accessory buildings, and structures such as patios, decks and balconies that sit 18 inches or more above the ground. North Fair Oaks is unincorporated county territory, but the county's jurisdiction here is a small pocket surrounded by Redwood City and Menlo Park, so this cap governs only inside the mapped S-50 overlay, not countywide.
Violations & Fines
Planning and Building can deny or condition a building permit that would push site coverage above 50%; plans must be revised to fit under the cap before a permit issues.
Frequently Asked Questions
Does the 50% lot coverage cap apply countywide?
What counts toward the 50% limit?
Sources & Official References
Other rules in San Mateo County
California rules heatmap·Compare San Mateo County to another location·View the California building setbacks & zoning overview
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