Many single- and multi-family homes in San Francisco can now add units. You can use the space for family members or to rent for extra income.
This process may take more than 18 months from when you decide to build.
It typically costs more than $125,000 in materials and labor to add a unit. Professional services for architects and engineers are typically 10% of construction costs. City fees range from 6 to 9% of construction costs. Your total cost can range widely depending on the specifics of your lot and project.
Your property and project plans affect what processes you must follow to get a building permit. Projects may be longer if they include multiple ADUs, seismic work, variances or a Certificate of Appropriateness.
If you do not follow our instructions carefully, it will take us longer to review and approve your application.
Check if you can add new units to your residential property
Decide if an ADU is right for you. Check to see if you can add an ADU at your address. Find out what you can build in your lot.
Decide if you will use the State or Local ADU Program
Learn about the differences between the State and Local ADU programs at SF Planning.
ADUs using the State or Hybrid Program are processed in a Permit Review Roundtable with a building permit.
ADUs using the Local Program require in-house review by the Planning Department before a building permit can be submitted. The planner assigned to review the Project Application will issue a Planning Approval Letter following review. The Planning Approval Letter, including all necessary attachments, will be required for submittal of a building permit application. Once you receive the Planning Approval Letter, please follow these instructions to submit a building permit.
Visit the Updated Planning Approval page to learn more.
Get a Historic Resource Review (HRR)
If you use the Local ADU program, and depending on your property’s historic status, you may need a historic preservation review.
Check your property’s historic status
Most properties in San Francisco are category B, which means potentially significant and not yet evaluated.
If your property is category B and your project involves major alterations visible from the street, you may choose to file a Historic Resource Review before filing your building permit to determine if your property is historic.
Design your ADU
ADU plans must follow City codes for neighborhood development and building safety.
Homeowners usually hire an architect or designer to create the plans.
Check our street tree rules
Your property must have 1 street tree per every 20 feet of frontage that borders the public right of way, or pay a tree in-lieu fee of $2,193.
Check rules for adding an ADU with the Local Program
If you are using the Local ADU program, follow these rules.
Post your notice in a building
If you are using the Local ADU program you must send a written declaration to the Rent Board.
You must post this in your building at least 15 days before you apply for your ADU application.
Decide if your project needs a full or site permit
You must decide whether to apply for a full permit or a site permit.
This is an important decision as it determines the process for reviewing a project.
Getting a full permit is a more condensed process. Most ADU applicants apply for a full permit.
If your project has a more iterative design and engineering, a site permit may help you save money. This way, you can avoid paying your engineer to do calculations that end up changing.
See more details in the Administrative Bulletin 032.
Fill out paper forms
You must fill out these paper forms and upload them with your application:
- Building permit application form
- Planning forms *
- Agent authorization form
- Fixture Count form
- Green energy form
- School Facility Fee form
For the Local Program, you will also fill out and post your written declaration.
* Only for ADUs using the Local Program.
Apply to build an accessory dwelling unit (ADU)
Follow these steps to apply online and complete the other required processes to build your ADU.
Last updated October 2, 2024