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Schedule ADU Consultation (415) 843-2387 ext: 986

San Francisco ADUs

Everything about building Accessory Dwelling Units in San Francisco, CA

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San Francisco ADU Guidelines Last Updated 01/26/21

The city government of San Francisco has updated its local zoning codes to comply with the State ADU mandate.
The California Building Code (CBC) 2019 is adopted.


City Hint: The city permitted a total of 509 ADU projects in the past year of 2019, which makes it above average for ADU production compared to other cities statewide.

Number of ADUs allowed:

Under state law, each single-family home may now build at least one Accessory Dwelling Unit (ADU). Owner occupied single-family parcels may build one Accessory Dwelling Unit (ADU) and one JADU. Multi-family parcels, per every four existing residential units, may build one Accessory Dwelling Unit (ADU), so long as the existing units were legally established.

Types of ADUs allowed:

Detached ADU, Attached ADU, Junior ADU are allowed. ADUs may be new construction or converted from existing space. JADUs must be converted from existing space.

Lot size:

Single family and multi-family residential properties will not be subject to the minimum lot size of the underlying zoning district or by ordinance for Accessory Dwelling Unit projects. ~ AB68

ADU size:

Residential lots will be allowed to add up to 850 square ft. for a one bed ADU or up to 1,000 square ft. for a two bed ADU, regardless of the underlying zoning standards of the property. A Junior Accessory Dwelling Unit is allowed up to 500 square ft.. According to California Residential Code, the minimum size of any living unit is 150 square ft. (including ADUs and Junior Accessory Dwelling Units). ~ AB-68


The maximum required setback for a detached new construction ADU shall be no more than 4 ft from the rear and side property lines. Setbacks will not be required for ADUs and Junior ADUs converted from existing space that was legally eastablished. Attached ADUs and conversions from existing space to be expanded will be required to comply with the setbacks of the underlying zone. ~ Updated: State Law AB-68


Properties which convert an existing garage to an Accessory Dwelling Unit or JADU will not be subject to replacement parking requirements. ~ AB68 & AB881 Update

Fire Safety:

Fire sprinklers are an example of active fire protection, and are now required in all new single family residential construction in California. In the case of adding an ADU to an existing single-family home, you will most likely only be required to add sprinklers to the new unit, adjacent spaces on the same floor, and along the exit path - unless directed otherwise at your pre-application meeting.

Smoke and CO Detectors Smoke alarms are required to be installed in all new dwelling units. These items must be hard-wired into the building’s electrical system.

Fire separation will be required between the ADU and any adjacent garage or property line and between any living space above.

Shape, materials and style:

Exterior modifications will be required to resemble those of the primary structure. Interior conversions of existing space are not subject to this requirement.


The main living space and the bedroom must have 7’-6” minimum ceiling heights. The other rooms in the unit - kitchen, bathroom, hallways, laundry rooms - can have ceilings as low as 7’-0”. Headroom is typically quite low when dealing with adding ground floor units to hillside properties, or in existing garages - and there are a number of exceptions for beams and sloped or furred ceilings - so clearances should be should be reviewed during the pre-application meeting. Reference 2013 SFBC/CBC Section 1208. Ceiling heights within the dwelling unit are governed by the California Building Code.

Design review:

It was a discretionary review process, but is now updated in 2018 to comply with State Law. California now requires that ADUs be approved through a ministerial process or "by right".

Minimum Room and Unit Sizes

The main living space and the bedroom must each be at least 7’ wide. There is no minimum room size for kitchens, but you must provide at least 36” of clear floor space in front of cabinets and appliances. Reference 2013
SFBC/CBC Section 1208.
Every dwelling unit must have at least one room that provides at least 120 square feet
of net habitable floor area. Other habitable rooms - bedrooms and living rooms, but not
kitchens, bathrooms, or storage rooms - must have at least 70 square feet of net floor area.
Reference 2013 SFBC/CBC Section 1208

Efficiency Dwelling Units: The Building Code has a specific category for an exceptionally small studio unit that has one room used for sleeping, cooking, eating, and living. The total area of the unit (including bathroom, closets, kitchen, and all living and sleeping space) must be at least 220 square feet. The unit is limited to two occupants. An additional 100 square feet of unit area must be provided for each occupant over this two-person limit. The primary living space (the area of the unit excluding the closet and bathroom) must at least 150 square feet. In addition to the size requirements, Efficiency Units must contain the following:
• a separate closet
• a kitchen with a sink, refrigerator, and cooking appliance; with at least 30” clear floor space in front of the counter and appliances
• a bathroom with a toilet and sink, and a bathtub or shower
• the same light and ventilation as required for other dwelling types
Reference 2013 SFBC/CBC Section 1208.


Between between 2020 and 2025, owner occupancy requirements will not apply to new Accessory Dwelling Unit (ADU)s. (applicable to new construction and conversion units) ~ Updated: State Law SB-13

Utility connections:

One of the advantages to constructing an ADU within an existing building rather than as a detached, free-standing structure is that the water and drain lines are usually (relatively) easy to tap into so that the services can be extended to the new unit’s bathroom and kitchen.

ADUs do require their own electrical service, with a dedicated electrical meter, circuit panel, and shut-off.

Historic Resource Determination

Most buildings in San Francisco that are 50 years and older that have not had an historic survey completed are classified as Category B resources, meaning that they are of potential importance. If your project involves alteration to a structure that has been identified (through a Historic Resource Determination Survey or other means) as a historic resource, or if the structure is 50 years old or greater, then there will most likely be additional materials and process involved in order to determine if the proposed work is appropriate. However, if your project is entirely within the existing structure and doesn’t involve changes to the front of the building, you will most likely not be affected by historic preservation guidelines.

Allowed Zones:

*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***

ADUs are permitted citywide in San Francisco. As of 2019, if the zoning district permits residential uses and includes existing residential building, then the lot is eligible for ADUs.

Street Curb Cuts

If you are removing a garage as part of adding an ADU, the Department of Public Works (DPW) will require that you also remove the curb cut that used to provide driveway access to that garage.

Street Trees & Front Yard Improvements

The Planning Department requires one street tree along the sidewalk of a typical 25’ wide residential lot. Adding a unit or legalizing a unit may trigger this requirement. If the property does not already have a street tree in place, one may need to be provided as part of the permit requirements. Reference SF Planning Code Section 138. Similarly, the Planning Code has requirements for landscaping and permeability in the front yard set back of most residential zoning districts. These are likely to be required as part of the Planning Department’s review of the project. Reference San Francisco Green Landscaping Ordinance, and the SF Planning Code Section 132

State Standards:

Note that many of San Francisco's requirements for ADUs are out of compliance with the State of California's mandate legislation. The city expects to update its ADU ordinance to comply in 2018. Particular areas to note are parking requirements and review process which will need to be updated to comply.

Rescue Window

Rescue openings must be provided from every sleeping room in a dwelling - this means each bedroom needs to have its own rescue opening. In the case of a studio apartment, the main living space needs a window or door that complies with the rescue opening requirement. If it is a window, it must be at least 5.7 square feet in size (5’ at the ground floor). The net opening can’t be less than 24 inches high or 20 inches wide, and the bottom can’t be more than 44 inches above the floor. It also needs to open freely to allow a person to climb out, meaning it can’t require any keys or tools to open. A door that leads to a public way or to a court that opens to a public way also meets the requirement. Reference 2013 SFBC/CBC Section 1029.

Neighborhood Notification

San Francisco has a neighbor notification process for building projects that meet certain criteria in Planning Code Section 311 and 312. This means everyone who lives within a certain radius of your property needs to be notified of the project and has an opportunity to file for a Discretionary Review, which is an opportunity for neighbors to express their concerns and provide input early in the project. There is also a pre application neighborhood meeting required. Adding an ADU does not automaticaly trigger Neighborhood Notification. If your project is built entirely within the existing footprint of the building, you will not have to go through this process.

Pre-Application Meetings

Prior to doing detailed design of your ADU project, it is possible to schedule an Pre-Application meeting with the Department of Building Inspection, and if necessary, the San Francisco Fire Department (for buildings with three or more units). The Pre-Application meeting is a chance to obtain feedback that can clarify many critical code issues. There is a fee to set up this meeting, but it can save a lot of time and money later in the construction process. Questions are submitted in advance of the meeting, and notes taken during the meeting of agreed-upon interpretations are sent back to the officials for review and their signatures. The written record becomes part of your building permit application.

Garbage Cans

DPW also enforces a San Francisco municipal code that requires garbage, recycling, and compost receptacles to be stored so that they are not visible from the street. In planning for an ADU that may take up a substantial amount of the garage space, care should be taken to maintain adequate space for the receptacles, or to provide a screened outdoor area where they may be stored. Information on acceptable screening enclosures can be found by searching for ‘Garbage and Recycling Receptacles’ at the Department of Public Works’ website:

Residential Building Code:

The California Building Code (CBC) 2019 is adopted.

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Detached ADU - Completed in 2020
1,003 sq. ft., 3 bed, 2 bath

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Costs / ROI



* upon completion of ADU


* based on local average price per sqft


* estimated by location


* 30 years / 5% interest rate / 20% down payment


Size: 500 sqft


Appreciation Estimate = (Base Value: $) / (Home's Living Space: sqft) * (ADU's Living Space: sqft)

Rental Estimate = (Rent Per Sqft: $5.41) * (ADU's Living Space: sqft)

Check your property's zoning, browse designs & get contractor estimates for your ADU project:

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Housable is providing information about specific properties that is furnished to users as a good-faith estimate of the development potential of a property. You should not in any way base your development, investments, or other financial decisions on this information. We strongly advise you to consult with an industry professional, such as a lender, realtor, contractor, or architect, who is sufficiently licensed and insured in their field, and who can work with you individually to confirm all requirements before moving forward with any real estate development or investment.