Everything homeowners need to know about building an accessory dwelling unit in San Francisco - size limits, setbacks, permits, and how California's state ADU law makes this one of the most ADU-friendly cities in the country, at least on paper.
Last verified: August 2026
8/10 · Very ADU-friendly
1,000 sq ft*
Max ADU size
18 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes San Francisco Planning Code Section 207.2 (State Accessory Dwelling Unit Program) and the city's Local ADU Program, layered on top of California's statewide ADU law (Gov. Code Sec 65852.2), for general reference - it is not legal advice. Regulations change; always confirm current requirements with SF Planning and the Department of Building Inspection (DBI) before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new construction)
850 sq ft for studio/1-bedroom; 1,000 sq ft for 2+ bedrooms
18 ft, plus up to 2 ft to match the primary dwelling's roof pitch
On multi-family lots, detached ADUs generally have no size cap
Attached (addition to primary home)
Same brackets as detached, or 50% of the primary dwelling's floor area on multi-family lots
Up to 25 ft
Reviewed under the state law's subdivision (a) standards
Converted (garage, basement, interior)
No separate size cap - limited to the existing structure, plus up to 150 sq ft for ingress/egress
Same as existing structure
Fastest, least expensive path since walls and roof already exist
Junior ADU (within the primary home)
Up to 500 sq ft
Same as primary structure
May require an owner-occupancy deed restriction if it shares a bathroom or kitchen with the main house
Allowed zoning districts
Allowed in RH, RM, RC, NC, and most other districts that permit residential use, on any lot with an existing or proposed dwelling. San Francisco also runs a Local ADU Program alongside the state-mandated one, with somewhat different eligibility rules - confirm which pathway applies to your project with SF Planning.
Additional standards
Setbacks, parking & other rules
Setbacks
4 ft from side and rear property lines for detached ADUs; no setback is required if the ADU replaces an existing structure in the same footprint, dimensions, and height
Parking
No additional off-street parking required for the ADU itself
Units per lot
Generally 1 ADU (detached, attached, or converted) plus 1 JADU on single-family lots; qualifying multi-family lots can add up to 8 detached ADUs under state law
Owner-occupancy
Not required for a standard ADU. A JADU sharing sanitation facilities with the main home may require a recorded owner-occupancy commitment
Building code
Must meet current California Building, Residential, Energy, Plumbing, Mechanical, and Electrical Code standards
Rent control
An ADU added to a building already covered by the SF Rent Ordinance (generally buildings occupied before June 13, 1979) typically becomes subject to the same rent-increase limits and just-cause eviction rules - confirm your building's status with the SF Rent Board
Impact fees
ADUs under 750 sq ft are exempt from development impact fees; larger units pay a proportional share, and units of 500 sq ft or less are also exempt from school impact fees
Ordinance history
How San Francisco's ADU rules got here
2016Citywide ADU ordinance adopted. San Francisco passed Ordinance No. 162-16, extending ADU eligibility citywide after earlier pilot programs had allowed ADUs in select supervisorial districts.
2017Statewide ADU law takes effect. California's Gov. Code Section 65852.2 begins requiring ministerial, by-right approval of qualifying ADUs in every city, San Francisco included.
2020State law tightens further. The AB 68/881/587/2299/671 package shrinks required setbacks, sets firm review timelines, and legalizes junior ADUs statewide; San Francisco updates its Planning Code to match.
2023Local ADU Program adopted. The city passed Ordinance No. 053-23 in April, creating a city-specific ADU pathway alongside the state-mandated one - though state housing regulators later flagged ambiguity about how the two programs interact.
2024Owner-occupancy eliminated, multi-unit ADUs expanded statewide. AB 976 permanently bars California cities from requiring owner-occupancy for standard ADUs, and SB 1211 allows qualifying multi-family properties to add up to 8 detached ADUs.
2026Standards updated. SF Planning's Director's Bulletin No. 3 on the State ADU Program was refreshed in June to reflect current size, height, and fee rules.
San Francisco's zoning is genuinely generous, but the process has historically been the bottleneck: Chronicle reporting on Department of Building Inspection data has put the median time from ADU permit issuance to completion at well over a year in past years, even though state law targets 60 days for the zoning review itself. Regionally, ADUs made up close to 28% of all Bay Area housing permits in 2024 as multi-family construction slowed, with the Bay Area adding roughly 2,761 new ADUs in 2023 alone.
Permit process
How San Francisco ADU permitting works
1
Pre-application check
Confirm your zoning district and whether the state-mandated program or SF's Local ADU Program better fits your project with SF Planning.
2
Prepare your plan set
You'll need a site plan, floor plans and elevations for the ADU, and (for size-limited units) plans of the existing home to verify the calculation.
3
Submit to SF Planning
ADUs meeting state standards get ministerial review with no discretionary hearing or design review, generally within the state's 60-day review clock.
4
Building permit review at DBI
Once Planning signs off, submit to the Department of Building Inspection for the building permit and plan check.
5
Construction & inspections
Schedule the standard framing, plumbing, electrical, and final inspections as work proceeds.
6
Rent registration (if renting)
If the property is subject to the SF Rent Ordinance, register the new unit with the SF Rent Board before placing tenants.
Fees, review timelines, and program eligibility change fairly often in San Francisco - confirm current figures with SF Planning and DBI before you budget or design.
Budgeting
What it costs to build an ADU in San Francisco
Garage conversion
Roughly $90,000-$200,000, the least expensive path since the shell already exists
Basement conversion
Roughly $120,000-$250,000, depending on ceiling height, egress, and utility access
New detached ADU
Roughly $200,000-$400,000+, reflecting San Francisco's high labor and land costs relative to most of the country
Plan review fee
SF Planning's published fee schedule starts around $1,671 for construction valuations in the $50,000-$200,000 band, with additional per-$1,000 charges above that
School impact fee (if applicable)
Roughly $3.79 per sq ft for ADUs over 500 sq ft under the city's 2026 impact fee schedule; smaller units are exempt
These are general ranges from local contractor estimates and regional reporting, not quotes - actual cost depends heavily on site conditions, finishes, and foundation work. San Francisco and the wider Bay Area consistently run at or above the high end of California's typical ADU cost range.
Before you apply
Tips for a smooth approval
Decide between the State Program and the Local ADU Program early. Eligibility and unit limits differ between them, and switching pathways mid-design can mean starting over.
Right-size your bedroom count. The size cap jumps from 850 to 1,000 sq ft once you add a second bedroom, which can change the math on a new detached unit.
Budget for a long runway. Even with ministerial zoning approval, full permit-to-completion timelines in San Francisco have historically run well over a year - plan financing accordingly.
Check your building's rent-control status before you rent it out. A pre-1979 building can bring the new unit under the city's Rent Ordinance.
Aim for the impact-fee exemption thresholds. Staying at or under 750 sq ft (500 sq ft for school fees) meaningfully lowers your total cost.
FAQ
Common questions
Do I need to live on the property to build an ADU in San Francisco?
No. California's AB 976 permanently bars cities from requiring owner-occupancy for a standard ADU. A junior ADU that shares a bathroom or kitchen with the main house may still require an owner-occupancy deed restriction.
How many ADUs can I build on my lot?
Generally 1 ADU (detached, attached, or converted) plus 1 JADU on a single-family lot. Qualifying multi-family lots can add up to 8 detached ADUs under state law.
Do I need extra parking for an ADU?
No additional off-street parking is required for the ADU itself.
How long does the permit process take?
Planning's zoning review targets the state's 60-day ministerial window. Full permit-to-completion timelines have historically run well over a year according to DBI data, though the city has worked to clear backlogs - confirm current timelines with Planning and DBI.
What's the maximum size for a detached ADU?
850 sq ft for a studio or 1-bedroom, 1,000 sq ft for 2 or more bedrooms, with a height limit of 18 ft plus up to 2 ft to match the main house's roof pitch.
How much does an ADU cost to build in San Francisco?
Garage conversions tend to run roughly $90,000-$200,000, basement conversions $120,000-$250,000, and new detached units $200,000-$400,000 or more, based on local contractor estimates and regional reporting. San Francisco typically runs at the higher end of California's cost range.
What's the difference between San Francisco's Local ADU Program and the state program?
Both allow ministerial, by-right approval, but the Local ADU Program has its own city-specific eligibility rules layered on top of the state minimums. Confirm which pathway applies to your project with SF Planning before you design.
Are ADUs subject to San Francisco's rent control law?
If the property is in a building already covered by the SF Rent Ordinance (generally one occupied before June 13, 1979), a new ADU typically becomes subject to the same rent-increase and just-cause eviction rules. Confirm your building's status with the SF Rent Board.
Can I rent my ADU out on Airbnb or a short-term rental platform?
San Francisco regulates short-term rentals separately and tightly, generally requiring the host's primary residence and capping unhosted rentals. Confirm current short-term rental rules with the city's Office of Short-Term Rentals before you finalize your design.
