Building an ADU in San Francisco

State program or Local program

San Francisco runs two ADU programs. Single-family homes choose between the Local and State programs. Multifamily buildings choose between the Local and State Hybrid programs. You cannot combine them.

State program. This follows California ADU law. Review is ministerial: a 60-day review from a complete application, no environmental (CEQA) review, no neighborhood notice under Planning Code Section 311, no discretionary review and no appeal. State ADUs are exempt from the local Planning Code except the standards in Planning Code Section 207.2. Work not related to the ADU still has to meet the Planning Code. State law keeps the city from putting some of these ADUs under the local rent control law.

Local program. This can allow more units. On an existing building with 4 or fewer legal units you can add 1 ADU plus 1 detached ADU. With 5 or more legal units you can add unlimited ADUs plus 1 detached ADU. The city can waive some Planning Code rules (density, open space, rear yard and exposure) for ADUs in existing buildings, but not building code rules such as ceiling height, ventilation, fire safety and exits. In exchange, Local program ADUs are subject to the city's rent control law. You also need Planning approval before you file for a building permit, and you must post and deliver a notice to the building's units at least 15 days before you apply.

Under the Local program you cannot add an ADU to a building that had an owner move-in eviction in the last 5 years or another no-fault eviction in the last 10 years. Evictions do not block an ADU under the State or Hybrid programs.

Read SF Planning's ADU page and Director Bulletin No. 3 to compare. Some older text on the Planning ADU page still talks about 2020 state laws as new; Director Bulletin No. 3 (updated June 2026) is the current summary of the State program. [1][2][4][5][6]

How big, how tall and how close to the lot lines

These are the State program limits from SF Planning's Director Bulletin No. 3.

Single-family lot:

• Detached ADU: up to 850 sq ft for a studio or 1 bedroom, up to 1,000 sq ft for 2 or more bedrooms. Height up to 18 feet, plus 2 feet for a roof pitch that matches the main house. 4-foot side and rear setbacks.
• Converted ADU (inside existing or proposed space): no size, height or setback limit beyond the space you convert. If you convert an existing accessory structure, you may expand it up to 150 sq ft only for entry and exit.
• Junior ADU: up to 500 sq ft of interior livable space, with at least an efficiency kitchen.
• Attached ADU: up to 850 sq ft (studio or 1 bedroom) or 1,000 sq ft (2+ bedrooms), or 50% of the existing home if that is larger. Height up to 25 feet. 4-foot side and rear setbacks. An attached ADU cannot be combined with other ADU types.

No setback is required if a detached ADU replaces an existing structure in the same location and at the same size and height.

Multifamily lot: you can build up to 8 detached ADUs on a lot with an existing multifamily building, but not more than the number of existing units, and there is no maximum size. You can also convert non-livable space into 1 ADU or up to 25% of the number of existing units. State ADUs cannot take space from an existing unit in a multifamily building or convert commercial space.

Every ADU needs its own entrance. The city's design rules set a minimum of 220 sq ft and 7.5-foot ceilings in living areas. HCD, the state housing agency, says a city's minimum size can't rule out an efficiency unit, which state law allows as small as 150 sq ft; ask the Planning Counter if you plan a very small unit. See Design an ADU that meets City codes for light, ventilation, exit and fire-safety rules. Confirm what fits your lot with the Planning Counter. [2][3][7]

Parking

San Francisco does not require additional parking for an ADU. [3]

Fees and costs

The city's own estimate is that adding a unit typically costs at least $125,000 in material and labor. Architects and engineers typically add about 10% of construction costs, and city fees range from 6-9% of construction costs. Hiring an architect for the plans costs $10,000 or more.

• Impact fees: the city says ADUs and junior ADUs smaller than 750 sq ft of interior livable space, or on lots with 3 or fewer existing units, are exempt. When impact fees apply, they are scaled to the size of the main home. State law, as HCD describes it, exempts ADUs of 750 sq ft of interior livable space "or less," which would also cover an ADU of exactly 750 sq ft. Confirm with the Planning Counter.
• Permit fees: you pay a filing fee before review starts and an issuance fee later. A site permit has at least four payments.
• School fees: DBI calculates San Francisco Unified School District fees from your permit application. Questions go to SFUSD at 415-241-6090.
• Water and sewer: the SFPUC's capacity charge guidelines say capacity charges do not apply when a single-family home adds an ADU, but do apply when multi-unit buildings add ADUs. That document was written for the 2017 ADU laws, so confirm current charges with the SFPUC at 628-652-6040.
• Fire sprinklers and alarms: Local program ADUs in buildings with 3 or more units may need a ground-floor fire alarm and sprinkler system, which can add a lot of cost.

For more on budgeting, see our ADU cost guide and ADU financing guide. [2][3][5][7][8]

How long it takes

State program ADUs get a 60-day review from the date of a complete application. When you apply you sign a Permit Application Processing Time Tolling Declaration about that 60-day period. Review does not start until you pay the filing fee.

State program ADUs filed as a full permit, with no other construction work, go through the city's Permit Review Roundtable. All city departments review your plans together and go over their comments with your design professional in a virtual meeting, at no extra charge. After you revise the plans, DBI schedules another roundtable. The city says this generally has a shorter review and issuance timeline than the Local program. Site permits are not eligible.

Projects take longer if they include multiple ADUs, seismic work, variances or a Certificate of Appropriateness. Local program projects need Planning approval first, which adds a step. For the general process, see our ADU permit process guide. [2][5][9]

Garage conversions and junior ADUs

Many San Francisco ADUs are built in existing garage or storage space. Under the State program, a converted ADU has no size, height or setback limit beyond the space itself. A junior ADU can be created within existing space, including an attached garage, and can be up to 500 sq ft. Many rear-yard structures can also be converted if they were built with a permit or are legal but no longer meet current zoning.

If the junior ADU shares a bathroom with the main home, you must record a deed restriction that includes an owner-occupancy requirement, either in the junior ADU or the main home.

An ADU may not remove housing services such as a garage, laundry room or storage space without a "just cause" reason. Under the Local program, you can also convert up to 25% of an existing unit's ground floor or basement habitable space, or more with Zoning Administrator approval.

See our guides to garage conversions and junior ADUs. [1][2][3]

Lot splits and duplexes (SB 9)

San Francisco offers streamlined SB 9 approval for a lot split, a duplex, or both. The lot must be in an RH-1, RH-1(D) or RH-1(S) zoning district. If there is an existing home, it must have been owner-occupied or vacant for the past 3 years. Planning reviews a complete application within 60 days. Full eligibility rules are in Director Bulletin No. 8. Start at SF Planning's SB 9 page, and see our SB 9 lot split guide. [10]

Renting it out or selling it

You can rent out an ADU, but not as a short-term rental. Any ADU rental must be for longer than 30 days. Local program ADUs, and ADUs that get Planning Code waivers in buildings that already have rent-controlled units, are subject to the city's rent control law.

In most cases you cannot sell an ADU separately from the main property. Under the State program, one ADU can be condo-converted if the lot has 4 or fewer existing units, the ADU application was submitted on or after May 1, 2025, and it is a detached ADU (or, with a new building, a detached or attached ADU) on a property that is a single-family home or entirely condominiums. Junior ADUs are not eligible. Adding an ADU will likely raise your property value and property tax. [1][2][4][11]

Pre-approved ADU plans

DBI runs a Pre-approved ADU Plans program for detached ADUs. Building designers submit plans designed for 25-foot lots, pay a $2,408 flat review fee per plan, and the approval lasts for the current code cycle. A pre-approved plan can then be used in a site-specific plan set with your building permit application. The city still checks Planning rules, soils, fire access, sewer drainage and other site-specific items. Pre-approved plans cannot be used in slope protection areas, landslide and liquefaction zones, Maher zones or flood zones. [12]

Permit steps in San Francisco

1. Check your property

   Look up your zoning and number of legal units on the Property Information Map, then use the city's eligibility page to see what you can build. [1][5][11]

2. Choose the State or Local program

   Compare the programs on SF Planning's ADU page. The State program gets a 60-day review and the Permit Review Roundtable; the Local program allows more units on some lots but adds rent control. [1][5]

3. Local program only: post notice and get Planning approval

   Post and deliver the ADU notice and send the declaration to the Rent Board at least 15 days before applying. Then file a Project Application (PRJ) and get a Planning Approval Letter, which you need to apply to DBI. [5][6]

4. Finish pre-application requirements

   Depending on the project these include a fire flow study for new floor area, historic resource review, recorded legal notices, Public Works right-of-way permits and a valid address. Your application will not be accepted if a required review is missing. [5]

5. Have plans drawn and prepare forms

   A licensed designer prepares plans to city codes. You complete the permit application form, the owner-signed Permit Applicant and Authorized Agent form, the 60-day tolling declaration, the ADU screening form and energy forms. Most ADU applicants file a full permit; the choice cannot be changed without resubmitting. [3][5]

6. Apply online and pay the filing fee

   Submit electronically through the city's building permit application. DBI checks the application for completeness, and review starts once the filing fee is paid. [5]

7. Plan review and Permit Review Roundtable

   State program full-permit ADUs get a virtual roundtable with all departments, at no extra charge. Your designer must attend, then revises and resubmits; DBI schedules a second roundtable. [5][9]

8. Get the permit and build

   Once approved, DBI issues the permit. Separate electrical, plumbing or mechanical permits may be needed. Track status with the city's permit tracking page. [5]

Pre-approved and sample plans

• Pre-approved Detached ADU Plans program (DBI)

  Designers get detached ADU plans for 25-foot lots pre-approved, and owners can use them in a site-specific permit application, outside slide, liquefaction, Maher and flood zones. [12]

Who to call

• SF Planning Counter (ADU questions)

  Which program fits your lot, zoning, Planning Code questions

  628.652.7300

  [1][2]

• SF Planning ADU team (email)

  ADU program questions: CPC.ADU@sfgov.org or pic@sfgov.org

  [1][3]

• Department of Building Inspection, ADU guidance

  Building code questions: dbi.adu@sfgov.org; application help: SFplanreview@sfgov.org; technical questions: techq@sfgov.org

  [3][5][9]

• San Francisco Permit Center

  In-person permit help (Mon 9-5, Tue-Fri 8-5)

  628-652-4900

  49 South Van Ness Avenue, 2nd floor, San Francisco, CA 94103

  [13]

• San Francisco Rent Board

  Local program ADU declarations; rent control questions (rentboard@sfgov.org)

  25 Van Ness Avenue, Suite #700, San Francisco, CA 94102

  [6]

• SFUSD Real Estate and Permit Office

  School impact fees (schoolimpactfee@sfusd.edu)

  415-241-6090

  135 Van Ness Avenue, Room 116, San Francisco, CA 94102

  [5]

Questions people ask