California ADU rules · San Francisco County
Can I Build an ADU in San Francisco?
Yes — you can build an ADU in San Francisco. California's statewide ADU law requires every city, including San Francisco, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
Local rule1 detached ADU + 1 JADU
One detached ADU plus one JADU per single-family lot.
Units on a multifamily lot
Local ruleUp to 2 detached ADUs + interior ADUs (≥1, up to 25% of existing units)
Interior conversion ADUs (at least 1, up to 25% of existing units) plus up to 2 detached ADUs — narrower than the state floor's up-to-8 detached on existing multifamily lots.
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
Local rule1,000 sq ft
850 sq ft for a detached ADU with one bedroom or less; 1,000 sq ft with more than one bedroom.
Max attached ADU size
Local ruleThe greater of 50% of the primary dwelling's gross floor area, 850 sq ft (≤1 bedroom), or 1,000 sq ft (2+ bedrooms)
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
Local rule16 ft
16 ft for a detached ADU on a single-family lot; 18 ft for a detached ADU on an existing/proposed multifamily, multi-story lot. An attached ADU may reach 25 ft (or the primary dwelling's height limit, whichever is lower), max 2 stories.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
CA state lawNo front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
Local ruleNone
San Francisco requires no parking for any ADU regardless of transit proximity, and no replacement parking when a garage or carport is converted.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
CA state lawOnly for a JADU
No owner-occupancy requirement for ADUs (the prior sunset was removed). A JADU may require owner-occupancy, principally where it shares sanitation with the main house.
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
Local ruleBuilding permit, Licensed design professional (most ADUs)
Building permit only — ministerial, with no discretionary planning review and no Section 311 neighborhood notification. A licensed design professional is required for most ADUs except small wood-frame single-family projects.
San Francisco-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Historic districts, landmarks & Article 10/11 properties
ADUs are allowed in historic districts and no Certificate of Appropriateness is required for a qualifying ADU/JADU, but Article 10/11 notification applies and the project must meet objective historic-preservation standards; demolishing a garage can trigger additional notice.
Coastal Zone / Coastal Act
State ADU law applies, but Coastal Act resource protections still govern; a Local Coastal Program amendment or coastal development permit review may be needed beyond the ministerial ADU path.
Very High Fire Hazard Severity Zones
No outright local ban, but the project must satisfy fire-safety and egress requirements; additional fire-alarm or sprinkler work may be required for multifamily ADUs.
San Francisco approves ADUs ministerially under Planning Code § 207.2 with no parking requirement and no neighborhood-notification (Section 311) review. Detached ADUs are capped at 850 sq ft (one bedroom or less) or 1,000 sq ft (larger), the local minimum unit is 220 sq ft, and most projects must be drawn by a licensed design professional — so the binding constraints in the city's dense, often historic fabric tend to be lot size, building separation, and Article 10/11 preservation review rather than entitlement.
Frequently asked questions
Can I build an ADU in San Francisco?
Yes. California's statewide ADU law requires San Francisco to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in San Francisco?
A detached ADU of at least 1,000 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in San Francisco?
Side and rear setbacks are limited to 4 ft. No front setback may block the mandatory 800 sq ft / 16-ft / 4-ft-setback ADU; otherwise per base zone.
Is parking required for an ADU in San Francisco?
None. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in San Francisco?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in San Francisco?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- SF Planning Code §§ 207.1, 207.2 (amended Oct. 2025)
- SF Planning Code § 207.2(d)(1)(B)
- SF Planning Code § 207.2(d)(3), (4)
- SF Planning Code § 207.2(e)(6), § 207.1(d)(15)(B)
- SF Planning Code § 207.2(e)(5)
- SF Planning Code § 207.2(e)(9)(A)-(D)
- SF Planning Code § 207.2(c)(4)
- SF Planning Code § 207.2(f); SF DBI ADU Resource Sheet
- SF Planning Code § 207.2(c)(2)
- Cal. Gov. Code § 66329
- SF DBI ADU Resource Sheet
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66315 (owner-occupancy)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-25. This is an AI-assisted summary of San Francisco's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with San Francisco Planning before relying on it.
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