San Bruno Accessory Dwelling Unit (ADU) Standards

        New laws were recently passed, and updates will be coming soon


Matt Jones, Assistant Planner


ADU Ordinance

Zones allowed

All residential zones
Lot restrictions

Must be single-family dwelling. Must meet lot coverage, setback and FAR requirements.

Minimum lot size
Large enough to meet lot coverage, setback and FAR requirements (likely 2,500 sf required)
Min / Max ADU size

150 sf / 640 sf

ADU building height

28 feet


Setbacks for new living area are the same as in the R-1 District. An attached ADU may continue the setback of the existing dwelling. An existing accessory structure converted to ADU must have setbacks sufficient for fire safety per the state law.

Parking requirements

One space is required unless state exemptions are met (ADU is within 1⁄2 mile of transit, in existing structures, in historic districts, within one block of car share locations, or in an area with residential parking permit rules that do not allow second units to get a permit). Tandem parking and parking in setbacks is allowed.

Owner occupancy

Owner must live in the main dwelling or the ADU

Sample fees from recently built projects*
ADU 1(426 sf, internal conversion): $2,825
ADU 2 (562 sf, detached): $4,456
Other requirements
  • Only one ADU per property is allowed.
  • ADUs can have at most one bedroom.
  • ADUs must comply with all requirements of the underlying zoning district.

A planner reviews the application for completeness, does a site visit and makes a determination. Making an appointment to meet with a planner in the initial stages of the project can help avoid challenges and is highly recommended.



Disclaimer: standards and process may vary. Consultation with the contact is recommended before starting any project.

*Fees are specific to each project and will vary. Fees change regularly. These are provided as examples only.

Download ADU Standards PDF

Updated: 12/11/2017