San Mateo County, CA Building Setbacks & Zoning: Structure Height Limits (2026)
Key Facts
- Max roof height
- 28 feet
- Front-setback plate height
- 10 feet
- Mechanical equipment allowance
- up to 36 feet
- District
- RH, Residential Hillside
Summary
In the county's RH (Residential Hillside) zoning district, homes are capped at 28 feet measured from natural grade, with a lower 10-foot plate height for any part of a building that extends into the front setback.
In the "RH" District, building height shall be limited in accordance with the following:
(a) Building height at the highest point of the roof shall not exceed 28 feet. Building height shall be measured as
the vertical distance from: (1) any point on the natural grade to the topmost point of the building immediately
above, or (2) any point on the lowest floor, if the lowest floor is below the natural grade, to the topmost point
of the building immediately above.
(b) Plate height for any portion of a building that extends into the front setback shall not exceed 10 feet. Plate height shall be measured as the vertical distance from: (1) any point on the natural grade to the bottom of the lowest ceiling joist where the framing of the roof begins, or (2) any point on the lowest floor, if the lowest floor is below the natural grade, to the bottom of the lowest ceiling joist where the framing of the roof begins. No second story shall be allowed in any portion of a building that extends into the front setback.
(c) Chimneys, pipes, mechanical equipment, antennae and other common facilities may extend beyond building
height limit up to a maximum of 36 feet as required for safety or efficient operation.
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
Section 8.110.060 sets the height rule for the unincorporated RH District: building height at the highest point of the roof cannot exceed 28 feet, measured from natural grade (or from the lowest floor if it sits below grade) to the topmost point of the building. Any portion of a building extending into the front setback is further limited to a 10-foot plate height, and no second story is allowed there. Chimneys, vents and similar equipment may extend up to 36 feet. This is the RH hillside district specifically, not every unincorporated residential parcel.
Violations & Fines
Building above the 28-foot roof height or 10-foot front-setback plate height without an approved exception is a zoning violation; the Building Official can require redesign or removal of the non-conforming portion before occupancy.
Frequently Asked Questions
How tall can a house be in San Mateo County's RH hillside district?
Can I build a second story over my front setback?
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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