Can I Build ADU in San Francisco, CA? (2026)
Find out if you can build a adu in San Francisco, CA. Rules, permit requirements, costs, and next steps.
Yes, ADUs are allowed in San Francisco, CA. California state law ensures by-right approval.
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a residential lot — also called a granny flat, in-law suite, or backyard cottage. In San Francisco, CA, ADUs are permitted by right under state law, making them one of the most accessible ways to add housing on your property. ADUs can be detached, attached to the main home, or created by converting an existing garage or accessory structure.
ADU Rules in San Francisco
ADU Rules in San Francisco: Detached ADU max size: 1200 sq ft. Attached ADU max size: 50% of primary dwelling up to 1200 sqft. Junior ADU (JADU): up to 500 sq ft, within existing structure. Setbacks: 4 ft side, 4 ft rear. Owner-occupancy: Owner-occupancy requirement eliminated statewide effective January 1, 2020 per AB 68 (Gov Code 65852.2(a)(6)). No owner-occupancy required for either the primary dwelling or the ADU.. State preemption applies: CA law requires San Francisco to approve compliant ADUs by right.
Costs & Fees
ADU permits in San Francisco: Total estimated permit cost: $3,000–$10,000 total permit fees depending on size and scope. Contact the San Francisco Department of Building Inspection (DBI) for current fee schedule.
Timeline
Ministerial approval required within 60 days per Gov Code 65852.2(a)(3). SF DBI (Department of Building Inspection) ADU permits typically processed in 2-6 weeks for plan check. SF Planning pre-approval may add time if design review triggered.
Next Steps
Next steps for building an ADU in San Francisco: 1. Review full ADU rules including size limits, setbacks, and parking. 2. Apply for an ADU permit through the San Francisco Department of Building Inspection (DBI) at https://dbidocs.sfgov.org/. 3. Hire a licensed contractor familiar with CA ADU requirements.
San Francisco Department of Building Inspection (DBI)
Frequently Asked Questions
Can I build an ADU (in-law unit) in San Francisco?
Yes. California state law requires San Francisco to permit ADUs by-right on all residential lots. You can build a detached ADU up to 1,200 sqft, an attached ADU, a garage conversion, or a Junior ADU (JADU) up to 500 sqft within your existing home. No owner-occupancy requirement applies. SF DBI processes ADU permits ministerially within 60 days. The SF Planning ADU Program provides pre-approved plans for common configurations.
What are San Francisco's Airbnb rules?
Short-term rentals in SF require a Certificate of Registration from the Office of Short-Term Rentals ($450/year). Your unit must be your primary residence — you must live there at least 275 days per year. Whole-home (unhosted) rentals are capped at 90 nights per year. Hosted rentals (you're present) have no night cap. Penalties for non-compliance are $484 per day. Register at ostr.sfgov.org.
What zoning system does San Francisco use?
San Francisco uses its Planning Code (not Municipal Code) for zoning. Residential zones are RH (House) and RM (Mixed Residential) — ranging from RH-1 (single-family) to RM-4 (high-density apartments). Neighborhood Commercial Transit (NCT) zones allow retail below residential. The Planning Code emphasizes rear yard preservation — the typical requirement is 25% of lot depth or 15 ft minimum for rear yards in most residential zones.
Do I need a permit to run a business from my home in San Francisco?
Yes. A Home Occupation Permit ($148 fee) is required for any business operated from a residence in San Francisco. Restrictions apply: no clients visiting, no non-resident employees, no external signs, and business use must be secondary to residential use. Violations can result in code enforcement action.
What are the front yard setback requirements in San Francisco?
In RH-1 (single-family) zones, the standard front setback is 15 feet from the front property line. However, SF Planning Code requires that new construction match the prevailing setback of the block face — if neighboring homes have deeper setbacks, yours must match. Side yards are typically 0 feet in SF's characteristic attached rowhouse pattern. Rear yards must be at least 25% of lot depth (minimum 15 ft).
Are solar panels required on new homes in San Francisco?
Yes. California's Title 24 Energy Code (effective 2020 for single-family) requires solar PV on all new low-rise residential construction. San Francisco also adopted its own solar mandate for commercial buildings in 2016. Properties in SF historic districts need Planning Department approval for solar panels visible from the street, but this cannot be denied for code-compliant systems.
How do I find the zoning for my San Francisco property?
Use the SF Planning Department's online map at sfplanning.org/zoning-map. Enter your address to find your parcel's zone designation, height/bulk district, and any overlay districts. You can also look up whether your property is in a historic district or on the list of individually designated landmarks.
Source: San Francisco Department of Building Inspection (DBI) — Building Regulations. Last verified April 5, 2026. View source