San Francisco has spent years making accessory dwelling units easier to approve. The number of ADUs that actually reached the city's housing stock has nevertheless moved downward for four straight years.
San Francisco added 223 accessory dwelling units in 2025, according to the Planning Department's latest Housing Inventory. That category includes both newly completed ADUs and previously unauthorized units that were legalized.
In 2021, the comparable figure was 330. The city recorded 300 in 2022, 266 in 2023, 235 in 2024 and 223 in 2025.
From 330 to 223 is a decline of about 32%.
The approval rules really have become more streamlined
The declining completion count is notable because the rules for qualifying state-law ADUs have become more ministerial.
San Francisco Planning's current State ADU guidance says a qualifying state-law ADU receives a 60-day review from the date the application is complete. Those applications are generally exempt from California Environmental Quality Act review, neighborhood notification and discretionary review, and the applicable permits are not subject to the same appeal process as many discretionary projects.
But the phrase “60-day review” can be misunderstood. It is a Planning review clock that begins with a complete application. It is not a promise that a homeowner can go from idea to occupied unit in 60 days.
After Planning review, a project can still involve building permits, plan coordination, utility work, contractor scheduling, financing, construction, inspections and final sign-off. A legalized existing unit follows a different physical path from a brand-new backyard or in-building ADU.
Faster review and fewer finished units can both be true
The Housing Inventory and the Planning review rules measure different stages of the pipeline.
The Housing Inventory asks whether units were actually completed or legalized in a given year. The 60-day state-law process describes how Planning handles a qualifying complete application. A city can therefore improve the speed of one approval stage while still seeing fewer units reach completion.
That distinction matters because permit reform is often used as shorthand for housing production. It is necessary to make approval predictable, but it does not by itself pay for construction, find a contractor, resolve site conditions or make a project economically worthwhile.
The decline began from a pandemic-era high
The numbers also need historical context. The 330 ADUs added in 2021 were the high point in the five-year sequence published by Planning. The subsequent decline is steady rather than a one-year collapse: 30 fewer in 2022, 34 fewer in 2023, 31 fewer in 2024 and 12 fewer in 2025.
Across 2021 through 2025, the city added or legalized 1,354 ADUs in total.
That is meaningful housing production. But the year-by-year direction raises a question that cannot be answered by pointing to the statutory review clock alone.
Where does an ADU fall out of the pipeline?
The city's public data makes the next investigation possible. Building-permit records contain filing, issuance and status information; inspection records show later progress; Planning's Housing Inventory captures completed and legalized units.
Linking those stages could distinguish several very different explanations: fewer people applying, projects spending less time in review but more time before construction, permits being issued and never built, or projects being completed on a lag that shifts them into later calendar years.
Until that work is done, the strongest conclusion is also the simplest: San Francisco's streamlined ADU rules and its falling annual count of completed or legalized ADUs coexist. One does not disprove the other.
For policymakers, that means the next useful question is not only “How fast did we approve it?” but “Did the approved unit become a home?”