San Francisco Zoning and ADU Guide for Homeowners and Sellers

Last updated November 13, 2026. Reviewed by the Cash Home Buyers CA team. Information comes from SF Planning and SF.gov; sources are listed at the end.

San Francisco has a local ADU program, follows the state ADU program, and runs a Dwelling Unit Legalization Program for units that were built without permits. If your house has an in-law unit or converted space that was never permitted, there are official routes to legalize it, and those routes shape what a buyer will ask for.

San Francisco ADU and legalization rules at a glance

Who administers it	San Francisco Planning, with permits through the Department of Building Inspection
ADU programs	Local ADU program and State ADU program
Legalizing an unauthorized unit	Many unauthorized units can be legalized through the Local or State ADU program if all requirements are met, or through the Dwelling Unit Legalization Program or the zoning district where density allows
Legalization Program limit	One unwarranted dwelling unit per lot, under Planning Code Section 207.3
Building code	All life safety requirements of the San Francisco Building Code must be met when legalizing
State pathway	California Government Code Section 66332 provides a path to legalize unpermitted ADUs and JADUs built before January 1, 2020
Affidavit	You may need to sign an Unauthorized Dwelling Unit Affidavit when applying for a building permit so a space is not used as another unit

Can I legalize an unpermitted unit in San Francisco?

Often, yes. San Francisco Planning says many unauthorized units are legalized through the Local or State ADU program as long as all requirements are met. The Dwelling Unit Legalization Program allows one unwarranted unit per lot.

Under the state pathway, local agencies must approve permits for eligible units built before January 1, 2020, even if they do not meet current zoning or development standards, provided the unit is not a substandard building under Health and Safety Code Section 17920.3. Life safety requirements of the Building Code still apply.

The city also notes that if an existing structure is used as a legal or unauthorized residential unit, you need Planning Commission approval through a Conditional Use Authorization before demolishing it.

How units and zoning affect selling a house in San Francisco

The number of legal units on record matters to buyers and lenders, and a 3R report shows what the city has on file. An unauthorized unit may cap the price or complicate financing. In California, sellers generally have to disclose known unpermitted work. Your choices are to pursue legalization, remove the unit, discount the price, or sell as-is to a cash buyer who accounts for the risk.

How to sell a house in San Francisco with an unpermitted unit

1. Check what the city has on record. Review the permit history and consider a 3R report.
2. Look at legalization routes. The Local ADU, State ADU and Legalization programs each have requirements.
3. Weigh the options. Legalize, remove, sell with a credit, or sell as-is.
4. Disclose honestly. A cash offer does not change what you must disclose, but it removes repairs and inspections from the timeline.

We buy San Francisco houses as they are, including houses with converted garages and in-law units. Read how selling a house as-is in San Francisco works, or see our San Francisco cash-offer process. For records see our San Francisco building permits guide, and if the house has been cited read our San Francisco code enforcement guide.

Not sure whether your unit is legal? Call (424) 435-2326 or request a cash offer. There is no cost and no obligation.

Three legalization routes for an unauthorized San Francisco unit

San Francisco Planning describes more than one way to bring an unauthorized unit into the record. The Local or State ADU program can legalize many units if all requirements are met. The Dwelling Unit Legalization Program allows one unwarranted dwelling unit per lot under Planning Code Section 207.3.

And where the zoning district allows the density, a unit may be legalized as an ordinary dwelling unit. Which route fits depends on where the unit sits, how it was built and what the lot allows, so a seller should ask Planning for a pre-application view before assuming the answer.

Every route has a common requirement: all life safety requirements of the San Francisco Building Code must be met when legalizing. That is the cost a buyer has in mind when they see a converted garage or an in-law unit, and it is the number a cash buyer prices when an owner prefers not to start a permit.

The state pathway for units built before 2020

The city also points to California Government Code Section 66332, which provides a path to legalize unpermitted ADUs and junior ADUs built before January 1, 2020.

Under that pathway, local agencies must approve permits for eligible units even if they do not meet current zoning or development standards, provided the unit does not create a health and safety hazard.

For a seller with an older in-law unit, the date matters: documents that show when the unit was built are worth locating before you speak to a buyer or a contractor.

The Unauthorized Dwelling Unit Affidavit

Some San Francisco permit applications require you to sign an Unauthorized Dwelling Unit Affidavit so that a space is not used as a separate unit.

If you have signed one on a past permit, the commitment travels with the property, and the buyer should know that the space is not meant to be rented as its own unit. Review your permit documents so that your disclosure and your listing describe the space accurately.

Steps for a seller with an unpermitted unit

• Gather evidence of when the unit was created, such as receipts, utility records and photographs.
• Check DBI’s permit tracking system for permits, complaints and any recorded affidavit.
• Ask Planning which legalization route could apply to the lot.
• Get a contractor estimate for the life safety work legalization would require.
• Decide whether to legalize, sell with a credit or sell as-is.
• Disclose the unit’s status on the Transfer Disclosure Statement.

More San Francisco ADU questions

Does the Dwelling Unit Legalization Program apply to every house?

It allows one unwarranted dwelling unit per lot, so a lot with more than one unauthorized unit will need another route. Ask Planning how your lot is treated.

Do I have to legalize a unit before I sell?

No. You do have to disclose what you know. A cash buyer can purchase the house with the unit as built and take on the legalization decision.

San Francisco zoning and ADU FAQ

Can I legalize an unauthorized unit in San Francisco?

In many cases yes, through the Local or State ADU program, the Dwelling Unit Legalization Program or the zoning district, as long as requirements are met.

How many unauthorized units can be legalized per lot?

The Dwelling Unit Legalization Program permits one unwarranted dwelling unit per lot under Planning Code Section 207.3.

Can I sell a San Francisco house with an unpermitted unit?

Yes. The sale is not legally blocked, but you should disclose the unit. A cash buyer can purchase the house as-is with the unit unpermitted.

What does the state pathway for unpermitted ADUs cover?

Government Code Section 66332 covers unpermitted ADUs and JADUs built before January 1, 2020, as long as the unit is not a substandard building.

Sources

• SF Planning: Accessory Dwelling Units
• SF Planning: Dwelling Unit Legalization Program FAQ
• SF Planning: Planning Director Bulletin No. 3, State ADU Program

This guide is general information, not legal advice. ADU and legalization rules change often; confirm requirements with San Francisco Planning.