Decoding the San Francisco Planning Department website late at night can be very frustrating for homeowners. When property owners try to figure out what is actually allowed on their land, the process can feel very confusing. San Francisco ADU Solutions has worked with hundreds of property owners over the years, and we frequently sit down at kitchen tables to discuss these exact challenges. We want to clear the confusion and walk through the most common questions San Francisco ADU Solutions receives about the permitting process for an Accessory Dwelling Unit (ADU) in San Francisco, CA.
How long does it actually take to get an ADU permit in San Francisco?
Homeowners often do not like this answer, but an ADU permit in San Francisco typically takes anywhere from six to twelve months on average to secure. Anyone claiming they can push plans through the Department of Building Inspection (DBI) in just a couple of weeks is not being realistic. Between DBI plan check, Planning Department review, and potential public notices if you are touching the exterior envelope in a historic district like Eureka Valley, the bureaucratic review process moves slowly. State laws were intended to speed things up to 60 days, but local backlogs in San Francisco are very real.
Can the city outright deny my ADU application?
Yes, although strict state legislation has removed a significant amount of local control. The city cannot deny a standard ADU simply because of parking minimums or because a neighborhood association objects to the project. However, the city can and will halt your ADU application if your property sits in a designated flood zone, has active uncorrected building code violations, or if your proposed structure violates strict rear-yard setback rules that are not protected by state override laws. Seismic safety and fire separation requirements present additional major hurdles during the ADU review process in San Francisco.
Do I need an architect or can I just use a draftsman?
Technically, a licensed architect is not always required for an ADU project. For straightforward interior garage conversions in the Outer Richmond neighborhood, a qualified local draftsman or specialized designer who understands Title 24 energy calculations can produce a complete set of plans. However, the moment you begin modifying structural load paths, underpinning a foundation on sloping San Francisco clay, or navigating complex property lines on tight Bernal Heights lots, hiring an engineer and a licensed architect is very important for a successful ADU build.
What's the deal with historical restrictions?
If your home is over 50 years old and located within a historic district or listed as an architectural resource, you should expect a much longer review process for your ADU. The Planning Department preservation staff will examine the plans to make sure your exterior additions do not negatively impact the historical integrity of the streetscape. Interior ADUs receive a bit more flexibility, but the moment you add a new exterior door or alter a roofline visible from the public right-of-way, your ADU project enters strict historic review territory in San Francisco.
How much should I budget for permit and city fees?
Property owners should plan on setting aside anywhere from $15,000 to $30,000 exclusively for city fees when building an ADU. This budget includes DBI processing fees, plan check fees, Department of Public Works fees if your project touches the sidewalk or sewer lateral, and school impact fees if your ADU is over 750 square feet. Water and power connection fees from the San Francisco Public Utilities Commission (SFPUC) can also surprise homeowners if the existing service lateral is not adequate for the new ADU.
Will building an ADU trigger a property tax reassessment?
This is a major concern for many homeowners, but the actual tax outcome is much more reassuring. Building an ADU does not trigger a full reassessment of your entire primary property under Proposition 13. Instead, the Assessor Office will only assess the added market value of the new construction itself. Your baseline property tax for the existing house remains locked in, while a separate supplemental tax bill is generated solely for the newly created square footage of your San Francisco ADU.