Bay Area region / California
South San Francisco ADU rules
& permit guide.
Planning an ADU in South San Francisco? Review local size, setback and parking requirements, then confirm the details for your property with the permitting agency.
Local source collected 2026-05-20 · View sources
Local requirements at a glance
Min/max ADU size
Min: 150 square feet Max: 1,000 square feet
Height
Detached: 18 feet; up to 20 feet for units where roof pitch is aligned with the roof pitch of the primary dwelling unit AND the site is located within ½ mile walking distance from transit. Attached: height allowed in underlying zoning district.
Setbacks
Front yard: distance required by underlying zoning. Street, interior, rear: 4 feet. Distance between structures: 4 feet, including eaves.
Parking
JADUs: No parking required ADUs: One spot may be required (tandem allowed). No parking required if: Within ½ mile walking distance from public transit; In a historic district; Converted within existing or proposed primary residence or accessory structure; Submitted with an application to create a new primary single- or multiple-unit dwelling; One block from a car-share vehicle; or On-street parking permits are required but not offered to ADU occupant.
Process
Confirm your parcel and ADU type with the local planning department, prepare the required plans, and follow the city's building permit checklist. Ask which utility, fire and site reviews apply before submitting.
Your next three steps
- Confirm the property's jurisdiction, zoning and site constraints with South San Francisco's planning department.
- Discuss the ADU type, dimensions and utility needs with your designer before finalizing a layout.
- Ask the permitting agency for its current application checklist, fee estimate and review process.
2026 state-law context
ADUs and JADUs have different occupancy rules
California generally prohibits local owner-occupancy requirements for ADUs. A narrow exception applies to certain separately sold affordable ADUs. For JADUs, owner occupancy generally applies when the bathroom is shared with the main home; separate-bathroom JADUs are treated differently under 2026 law. Check the HCD handbook and your project's permit conditions.
Older local summaries may not reflect the latest state changes. Read HCD’s March 2026 handbook, pages 32–33.
Questions for your first planning conversation
- Which approval path applies to my building and ADU type?
- Do easements, trees, slope, access or fire conditions affect placement?
- Which utility upgrades and agency reviews should be included in my budget?
- Are preapproved plans available, and what site work still needs review?