Exterior entrance of an Accessory Dwelling Unit
Credit: San Francisco Planning
Citywide

Accessory Dwelling Units

Accessory Dwelling Units (ADUs), also called secondary units, in-law units, or cottages, are units added to existing and new residential buildings. Adding an ADU to your property can provide several benefits, such as providing housing for family members, simplifying your lifestyle, and increased financial flexibility.

Each ADU program offers a variety of benefits. Check out this chart.
Ready to apply for a permit to add an ADU? Start your application online.

In 2016, San Francisco's Accessory Dwelling Unit Program became available Citywide to all zoning districts that permit residential use. As of January 2020, California implemented new laws that govern ADUs statewide, allowing ADUs to be added to Single- and Multi-Family buildings. 

Types of ADUs

There are four ADU types:

  1. Conversion ADUs are new units that convert space in a residential building.
  2. Attached ADUs are new units that expand a residential building. 
  3. Detached ADUs are new free-standing buildings located on a residential property. 
  4. Junior ADUs (JADU) are a new type of ADU that convert up to 500 square feet of space in a single-family structure. JADU requires owner-occupancy in either the remaining portion of the single-family home or the newly created JADU.

The type of ADU which can be added to a property depends on your building type and the ADU Program. See the relevant tab for your type of building to learn more about the ADU Program options. 

Legalization of Unauthorized Unit

In some cases an unauthorized unit already exists on the property without permits. Use this Legalization of Unauthorized Units Checklist to review what items are required. More information is available on the Department of Building Inspection (DBI) website.

Below are further requirements, guidelines, and resources for ADUs (reminder: find your zoning information using the Property Information Map).

Three ADU Programs are available for single-family buildings: Local, State, or Hybrid.

Local Program

This program allows adding ADUs to an existing or proposed single-family building (subject to relevant requirements and Codes).

  • Types of ADUs allowed: Conversion, Attached, and Detached (may be new construction or converted from existing space)

These new, detached ADUs must be located within the buildable area of the property. For detached ADUs allowed outside of the buildable area, please see the State program.

Number of ADUs allowed*

Existing buildings

  • 4 or less legal dwelling units on the lot: 1 ADU allowed
  • 5 or more legal dwelling units on the lot: unlimited ADUs allowed

There is no limit on the number of ADUs allowed for projects undergoing Mandatory or Voluntary Seismic (AB-094) upgrades.

New building construction

  • Where the zoning district allows the construction of 4 or less units: 1 ADU is allowed
  • Where the zoning district allows the construction of 5 or more units: unlimited ADUs allowed
Waivers from the Planning Code

This program offers waiver, or exceptions, to some Planning Code requirements for ADUs added to existing buildings. When these waivers are granted, a Costa-Hawkins Regulatory Agreement may be required, which subjects the ADU(s) to rent control:

Draft Regulatory Agreement: If the subject lot includes Rental Unit(s) (as defined by Section 37.2(r) of the Administrative Code), and Planning Code waivers are granted, the new unit(s) will be subject to rent control. Generally speaking, these existing buildings are already subject to rent-control. A Regulatory Agreement will be created adding the new ADU(s) under rent control. Please see a sample of the agreement here. The Regulatory Agreement will be edited by Planning staff to reflect project specific conditions, and is required to be fully executed prior to permit issuance.

* Find out how many units are currently on your property and how many units are allowed by using our Property Information Map.

State Program

This State-mandated program allows adding one ADU to an existing or proposed single-family building. These ministerial program ADUs are the most flexible in that compliance with some of the Planning Code requirements (e.g. rear yard, exposure, etc.) is not required. They are only permitted on properties where there are no other ADUs.

  • Types of ADUs allowed: Conversion, Attached, and Detached (may be new construction or converted from existing space)
  • Number of ADUs allowed: maximum number of 1

Hybrid Program*

This State-mandated program allows adding one ADU and/or a Junior ADU (JADU) to an existing or proposed single-family building. Hybrid ADUs need to comply with Planning Code requirements (e.g. rear yard, exposure, etc.), except for density. This means that detached ADUs must be located within the buildable area of the lot. For detached ADUs that are allowed outside of the buildable area, please see the State Program.

  • Types of ADUs allowed: Conversion, Detached, and Junior ADUs (may be new construction or converted from existing space)
  • Number of ADUs allowed: maximum number allowed is 1 ADU + 1 JADU

* Due to specific language in the Government Code, San Francisco has two State-mandated ADU options: State and Hybrid programs, which may differ from other jurisdictions. To learn more, please contact us.

Three ADU Programs are available for multiple-family buildings: Local, State, or Hybrid.

Local Program

This program allows adding ADUs to existing or proposed multi-family building (subject to relevant requirements and Codes).

  • Types of ADUs allowed: Conversion, Attached, and Detached (may be new construction or converted from existing space)

These new, detached ADUs must be located within the buildable area of the property. For detached ADUs allowed outside of the buildable area, please see the State program.

Number of ADUs allowed*

Existing buildings

  • If 4 or less legal dwelling units are on the lot = 1 ADU is allowed
  • If 5 or more legal dwelling units are on the lot = unlimited ADUs allowed

There is no limit on the number of ADUs allowed for projects undergoing Mandatory or Voluntary Seismic (AB-094) upgrades.

New building construction

  • Where the zoning district allows the construction of 4 or less units = 1 ADU is allowed
  • Where the zoning district allows the construction of 5 or more units = unlimited ADUs allowed
Waivers from the Planning Code

This program offers waivers, or administrative exceptions, to some Planning Code requirements for ADUs added to existing buildings. When these waivers are granted, a Costa-Hawkins Regulatory Agreement may be required, which subjects the ADU(s) to rent control:

Draft Regulatory Agreement: If the subject lot includes Rental Unit(s) (as defined by Section 37.2(r) of the Administrative Code), and Planning Code waivers are granted, the new unit(s) will be subject to rent control. Generally speaking, these existing buildings are already subject to rent-control. A Regulatory Agreement will be created adding the new ADU(s) under rent control. Please see a sample of the agreement here. The Regulatory Agreement will be edited by Planning staff to reflect project specific conditions, and is required to be fully executed prior to permit issuance.

* Find out how many units are currently on your property and how many units are allowed by using our Property Information Map.

State Program

This State-mandated program allows adding one ADU to an existing or proposed multi-family building. These ministerial ADUs are the most flexible in that compliance with some of the Planning Code requirements (e.g. rear yard, exposure, etc.) is not required. They are only permitted on properties where there are no other ADUs.

  • Types of ADUs allowed: Attached and Detached (may be new construction or converted from existing space)
  • Number of ADUs allowed: maximum number of 1.

Hybrid Program*

This State-mandated program allows adding ADU(s) to an existing multi-family building. This ministerial program does not allow the addition of ADUs to new construction of multi-family properties. Please refer to Local or State Program for this option.

  • Types of ADUs allowed: Conversion and Detached.
Number of ADUs allowed

The maximum number of ADUs allowed is as follows:

  • Conversion ADU: 1 ADU is allowed to convert an existing space or up to 25% of the existing number of units, whichever is greater.
  • Detached ADU: 2 ADUs are allowed

ADUs need to comply with Planning Code requirements (e.g. rear yard, exposure, etc.), except for density. This means that these detached ADUs must be located within the buildable area of the property. For detached ADUs allowed outside of the buildable area, please see the State program.

* Due to specific language in the Government Code, San Francisco has two State-mandated ADU options: State and Hybrid programs, which may differ from other jurisdictions. To learn more, please contact us.

How does an ADU differ from a residential unit?
An ADU is a type of residential unit. ADUs are allowed to exceed the allowable density of a lot, which is defined by the zoning district. Some ADUs benefit from exceptions to certain Code requirements and require deed restrictions while density-conforming residential units do not. Check here to decide if an ADU is right for you.

Where can I put an ADU in my building?
Many ADUs are converted from existing storage or garage space. You may also build an expansion, a stand-alone structure, and add ADUs in conjunction with new construction, depending on the program. Please note that an ADU may not remove housing services, which includes garage, laundry room, storage space, etc., without a “just cause” reason to sever the housing service.

ADUs proposed under the Local Program must provide a Notice of Addition of ADU(s) to unit(s) and a Declaration to the San Francisco Rent Board to ensure housing services are not removed without a “just cause” prior to submittal of a permit. Please see here for more details. 

Can I add rooms on the ground floor without creating an ADU 
Yes, you may create living space in your home without creating an ADU. You may need to sign the Unauthorized Dwelling Unit Affidavit when you are applying for your building permit to make sure this space won’t be used as another residential unit. 

Which ADU program or type of ADU is best for me?
Each ADU program offers a variety of benefits. Typically, you may be eligible to pick the program that best suits you. However, depending on your property type, location of your ADU, or property history, you may only qualify for one ADU program.

You can pick from a variety of ADU types that are outlined here. After you’ve determined a type of ADU that you would like to add, you can check which program offers your desired ADU and if your property qualifies by looking at the single-family or multi-family tabs.

If you’re still unsure, you can also check with a planner by emailing us at CPC.ADU@sfgov.org.

I have an existing rear yard structure, what can I do with it?
Many rear yard structures can be converted into an ADU if they are built with a building permit or is an existing structure that is no longer allowed under current zoning regulations. Expanding an existing rear yard structure is only allowed if it’s located within the buildable area of your property.

Depending on the existing structure, you may be able to demolish and replace it with a new, freestanding, detached ADU that follows the required setbacks. If the existing structure is used as a legal or unauthorized residential unit, you will be required to receive Planning Commission’s approval for a Conditional Use Authorization prior to demolishing the structure.

If you’re still unsure what to do with your existing structure, you can email us at CPC.ADU@sfgov.org.

What if there’s been a recent eviction in the building?
Under the Local Program, ADUs cannot be constructed in residential buildings that have had owner move-in evictions in the last five (5) years, or other no-fault evictions in the last ten (10) years prior to the permit application. In case of temporary tenant evictions for capital improvements, there is no prohibition as long as a declaration from the property owner was submitted notifying the tenant of their right to reoccupy the unit.

Evictions do not preclude adding an ADU(s) through the State or Hybrid programs.

Can I use my ADU for short-term rentals?
No. Accessory Dwelling Units are ineligible for the Short-Term Rental program.

Can I sell my ADU?
Typically no; however, some exceptions may apply. Specifically, ADUs added per the Local Program to buildings undergoing soft-story seismic retrofitting (Mandatory per Chapter 4D of the Building Code or Voluntary per Department of Building Inspection Administrative Bulletin No. 094) maintain eligibility to enter the condo-conversion programs, if such programs are available in the future.

Review Process: What’s involved?
Please review the step-by-step process outlined here.

Does the Planning Department participate in Department of Building Inspection Pre-Application Meetings?  
The Department of Building Inspection (DBI) holds Pre-Application and Pre-Addendum Plan Review Meetings in accordance with DBI Administrative Bulletin AB-028. The Planning Department voluntarily participates in Pre-Application Meetings hosted by DBI for projects that propose Accessory Dwelling Units (ADU).

The Planning Department’s participation in these meetings is not subject to the process or requirements outlined in AB-028 and is provided as a courtesy to the applicant to provide insight into Planning Department requirements in effect at the time of the meeting. These requirements (including the Planning Code, policies, guidelines, etc.) may change over time. As such, the Planning Department’s guidance and responses provided during the meeting, in follow-up communication, and/or reported in the meeting notes are intended to reflect requirements in effect at that time and do not constitute an approval of the project, a final determination regarding Code-compliance, or an official Planning Code Interpretation by the Zoning Administrator.  The feedback provided is based on a preliminary review of information provided by the Applicant and is intended to be advisory only.

If needed, a formal written determination can be requested from the Zoning Administrator through a Letter of Determination. For follow-up questions, please contact us. 

I need to make some changes to my approved ADU. How do I do that? 
Changes to your approved ADU drawings may require a new building permit application. Some changes can be approved at our Planning Counter while others require in-house review. To learn more, please contact us. 

What are the benefits of the Local Program?
ADUs in the Local Program may benefit from the following:

  • Streamlined review
  • Opportunity to build unlimited ADUs on some multi-family lots or when going through some seismic retrofits
  • Receive waivers from certain Planning Code requirements for existing buildings

Depending on your project, some ADUs in the Local Program may be subject to the Planning Department’s review process and the City’s rent control law. These ADUs will not only contribute to the City’s housing stock, but also provides affordable housing units for middle-class households.

What are the benefits of the State and Hybrid Programs?
ADUs in the State and Hybrid Programs benefit from ministerial and streamlined review, which means they are subject to the following:

  • 60-day review timeframe from date of complete application
  • No subjective design review, except for standards that prevent adverse impacts on any real property that is listed in the California Register of Historic Resources
  • Not subject to review under the California Environmental Quality Act (CEQA)
  • Not subject to Planning Code Section 311 neighborhood notification requirements
  • No discretionary review opportunity
  • Shortened appeal window with appeals heard within 10-30 days of filing
  • State law would prevent the City from subjecting some ADUs to the rent stabilization provisions (rent control) of the San Francisco Rent Ordinance.

Contact the City about your ADU

Email the ADU Team at CPC.ADU@sfgov.org

Please note that the information provided in our correspondence is based on Planning Department requirements in effect at the time of that communication and on a preliminary review of information provided by the requestor. Planning’s requirements (including the Planning Code, policies, guidelines, etc.) may change over time.

As such, the Planning Department’s guidance and responses provided are intended to reflect requirements in effect at that time and do not constitute an approval of the project, a final determination regarding Code-compliance, or an official Planning Code Interpretation by the Zoning Administrator. The feedback provided is intended to be advisory only.