Setback Rules: San Mateo vs South San Francisco
How do setback rules rules compare between San Mateo, CA and South San Francisco, CA?
San Mateo and South San Francisco have similar restriction levels.
San Mateo, CA
San Mateo County
San Mateo establishes minimum residential setbacks by zone district in Title 27, Chapter 27.22 and the building line/setback standards in Section 27.38.100. Single-family zones require front setbacks of 20-25 feet, side yards of 5-10 feet, and rear yards of 20 feet or 20% of lot depth.
View full San Mateo rules →South San Francisco, CA
San Mateo County
In unincorporated San Mateo County, residential side yards are generally at least 5 feet and rear yards at least 20 feet, while the required front yard is set by the combining 'S' (site) district shown on the Zoning Maps. Setbacks vary significantly by district.
View full South San Francisco rules →Key Facts Comparison
| Fact | San Mateo | South San Francisco |
|---|---|---|
| Front Yard (R-1) | Typically 20 feet | - |
| Interior Side Yard | 5 feet minimum | - |
| Rear Yard | 20 ft or 20% of lot depth | - |
| Daylight Plane | Limits height near property lines | - |
| Code Reference | SMMC Ch. 27.22 and §27.38.100 | - |
| Side yard (typical residential) | - | At least 5 feet |
| Rear yard (typical residential) | - | At least 20 feet |
| Front yard | - | Set by combining 'S' district / Zoning Maps |
| Planned Ag (residential/non-ag) | - | 50 ft front, 20 ft side, 20 ft rear |
| Allowed projections | - | Eaves 2 ft; porches 6 ft (front), 3 ft (side/rear) |
| Code basis | - | Zoning Reg. Sec. 8.68.030 & Ch. 8.340 |
Highlighted rows indicate differences between cities.
San Mateo FAQ
What is the front setback in San Mateo residential zones?
In most R-1 zones, the front setback is typically 20 feet. Specific requirements depend on the zone district.
What is the daylight plane in San Mateo?
The daylight plane limits building height based on distance from property lines. It prevents tall structures from overshadowing neighboring properties.
Can I build an ADU with reduced setbacks?
Yes. Under Chapter 27.19, ADUs may have 4-foot side and rear setbacks. Converted garages in the same footprint require no setback.
South San Francisco FAQ
What are the setbacks for a house in unincorporated San Mateo County?
Typically at least a 5-foot side yard and a 20-foot rear yard, with the front-yard depth set by the combining 'S' district shown on the Zoning Maps. Setbacks vary by district, so check your specific parcel.
Why does my front setback differ from my neighbor's?
Front-yard depth is governed by the combining 'S' (site) district mapped for each area on the Zoning Maps, so it can differ between neighborhoods. The mapped front yard governs over other conflicting provisions.
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