All ADU Regulations

San Bruno, California

San Bruno has updated its ADU ordinance to comply with new state laws. Below are the up-to-date requirements for permitting an ADU in San Bruno.

October 28, 2020
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All properties zoned for single family or multi-family with the following zoning codes are eligible for ADUs, including:

  • R-1, R-2, R-3, R-4
  • P-D where residential use is allowed
  • Specific Plan areas where residential use is allowed.

Number of units

1 ADU and 1 Jr. ADU (JADU) are allowed on each property.

Building size

The maximum ADU you can build depends on your zoning and ADU type:

  • 500 sq. ft. for a JADU
  • 800 sq. ft. for properties that are already built to the maximum floor area ratio of the lot
  • 850 sq. ft. for a one bedroom ADU
  • 1,000 sq. ft. for a 2+ bedroom ADU
  • Attached ADUs cannot be greater than 50% of the existing home’s floor area.

Building height

Detached ADUs can reach a maximum height of 16 feet. Attached ADUs can reach the same height as the main structure, assuming they comply with municipal code (including daylight plane).


Minimum setbacks of 4 feet from the side and rear lot lines, as well as 6 feet from any existing structures are required for detached ADUs. The ADU must also comply by the required front setback of the zoning district.


No additional parking is required for ADUs if they are within 0.5 miles of public transportation (a bus stop, train station, etc.). When converting a garage or carport, replacement parking is not required.


Owner occupancy is not a requirement for permitting an ADU from January 1, 2020 until January 1, 2025. This is a great opportunity for rental property owners to increase their yields in a cost-effective way.


While long-term rentals are permitted for ADUs, short-term rentals (e.g. Airbnb) are not permitted in San Bruno.


Do you have a utility easement over your property? Are you on a lot with an irregular shaped lot? A custom ADU might be right for you. Reach out to us and we’ll help you build a custom ADU to fit your unique property characteristics and local regulations!

Design and build with confidence.