ADU regulations in San Francisco
San Francisco allows ADUs in all residential zones, including buildings with four or more existing dwelling units, and does not require owner occupancy for most ADU types.
You can generally build through the state program or the city’s local track. Each is governed by a different section of the planning code, and which one applies affects how many ADUs you can build and whether rent control covers the finished unit.
The San Francisco Planning Department and the Department of Building Inspection both review ADU applications. The Fire Department is also involved on larger or more complex projects. Learn all three agencies’ expectations early to keep the permit process moving.
What is an ADU under San Francisco’s program?
An accessory dwelling unit is a secondary, independent residential unit on the same lot as a main residence. It has complete living facilities: a kitchen, bathroom, and sleeping area.
San Francisco allows these units, sometimes called in-law units, on most residential property in the city. The state program behind them aims to add housing without large-scale new development. Every ADU must still meet basic safety and habitability standards, whichever type you build.
Two paths: state ADU program vs. local ADU program
Homeowners generally choose between two regulatory paths, each with its own requirements and tradeoffs.
The state ADU track (Section 207.2)
Planning Code Section 207.2 governs this program, which implements California’s statewide ADU legislation under Government Code Sections 66314 through 66333. It requires ministerial approval for compliant ADUs, so the city cannot use discretionary review to deny a qualifying application.
ADUs built under the state track may be exempt from San Francisco’s rent control law, depending on the unit type and how it was approved.
The local ADU track (Section 207.1)
San Francisco’s own program, under Planning Code Section 207.1, goes beyond the state minimums. It includes opportunities to build multiple ADUs on certain multifamily buildings or during qualifying seismic retrofit work.
ADUs built through the local track are subject to rent control, unlike some units built under the state track. That difference matters if you plan to rent the unit long term.
Planning Director Bulletin No. 3 explained
The bulletin, titled “State Accessory Dwelling Unit Program,” is San Francisco Planning’s official guidance on the state and local requirements that apply to ADUs approved under Section 207.2.
Homeowners and designers use it to confirm requirements for a given property, because it pulls together rules otherwise spread across local and state law. Read it early, and talk to SF Planning staff, to avoid redesign later.
ADU types allowed in San Francisco
San Francisco recognizes several ADU types, each with its own construction and permitting path. Start the choice by looking at your existing structure and available yard space.
Detached, attached, and converted ADUs
A detached ADU is a standalone structure separate from the main residence. An attached ADU shares a wall with the primary building. A converted ADU repurposes existing space, such as a garage or basement, within the current building envelope.
San Francisco permits all three types, subject to zoning and buildable area requirements for each property. A converted ADU tends to clear review faster than a detached one, because less new construction is involved, and it often needs a simpler building permit application.
A detached ADU typically gets the most extensive building permit review of the three, because it needs a new foundation, new utility connections, and full compliance with current residential building codes.
Junior accessory dwelling unit
A junior accessory dwelling unit (JADU) is a smaller unit created within the walls of an existing single-family home, typically capped at a modest size under state law.
A JADU often shares some systems with the main residence. Its requirements differ from a full ADU’s, including different size limits and, in some cases, different occupancy expectations.
Number of ADUs allowed per property
The number depends on the building’s existing unit count and on whether it is undergoing seismic retrofitting.
For lots with four or fewer existing dwelling units, or where zoning would permit four or fewer, the local track generally allows one ADU.
Properties undergoing mandatory or voluntary seismic retrofit work may qualify for unlimited ADUs plus one additional detached ADU under specific planning code provisions. This is one of the more generous provisions in the city’s ADU framework.
Larger multifamily buildings with more than four existing units may qualify for additional ADUs beyond the baseline, depending on the building and program. If you are unsure how many units your lot supports, confirm with SF Planning before you finalize a design. A neighbor’s approval does not always transfer to your property.
Zoning, buildable area, and occupancy requirements
A property’s zoning district sets height limits, setbacks, and allowed density before any ADU-specific rule applies.
Buildable area limits, set by the planning code and clarified through Zoning Administrator bulletins, define how much of a lot can be built on. They affect detached ADU placement most, especially on the narrow or irregular lots common in the city.
San Francisco does not require owner occupancy for most ADU types, so investors and landlords can add ADUs without living on site. That flexibility is part of why San Francisco is generally considered one of the more permissive ADU markets in California.
Rent control, parking, and fire safety
Rent control
Rent control applies differently depending on which program governs your ADU. Units built under the local track are generally subject to the city’s rent control law. Some units built under the state track may be exempt, depending on the circumstances and how the unit was approved.
This matters for anyone planning a long-term rental, because rent control status affects what you can charge and how you can adjust rent over time. Short-term use is a separate matter with its own city rules, so confirm your intended use with a professional before you finalize your design.
Parking
Current state and local rules have reduced or eliminated parking requirements for many ADU types. Losing existing off-street parking to a detached or converted ADU can still matter in practice, even where code no longer requires it.
Fire safety
Fire safety requirements apply under either program. A new dwelling unit must meet current life-safety standards, including egress and smoke detection, before occupancy is approved. A unit occupied full time by a tenant or family member is held to the same fire and building safety standards as any other habitable space in the city.
The ADU permit process
Most San Francisco ADU projects start with an ADU screening form that confirms basic eligibility before detailed plans are drawn.
An optional pre-application meeting with SF Planning Department staff, the Department of Building Inspection, and the Fire Department can surface code issues before much design work is done. It helps most on detached ADUs, where setbacks, parking loss, and utility connections tend to come up.
Once plans are ready, the ADU application goes through formal review at the planning counter and, for most projects, through the Department of Building Inspection for building permit approval. You need a building permit whether you build a detached unit, convert a garage, or attach a structure to your main residence.
Check your property’s zoning, historic status, and existing residential units on the city’s Property Information Map early. It sets realistic expectations and reduces the chance of a redesign mid-review.
Plan for a longer building permit timeline if you are building multiple ADUs on one property, through a seismic retrofit or a larger multifamily building, because DBI and Planning have more to review. Parking impact from removed spaces is typically handled in the same permit review, not a separate approval.
Condo conversion and deed restrictions
Adding an ADU can affect a building’s eligibility for condo conversion in some circumstances, particularly where an ADU is combined with seismic retrofit work under the citywide condo-conversion lottery rules.
Some ADU approvals also require a deed restriction recorded against the property. It documents the unit’s status and any use restrictions for future owners. Talk to a real estate attorney if you are unsure how it could affect a future sale.
ADU costs and what to budget for
ADU costs vary with unit type, size, and site conditions. Budget construction, permit fees, and design work as separate items, because a single lump sum rarely covers the whole project.
Regulatory requirements shape design, so get advice on the planning code and on construction costs early, and estimate them together. If you plan to rent the unit, factor rent control status into your financial planning, since it limits how you can price the unit over time.
Key takeaways
- San Francisco allows ADUs in nearly all residential zones, with no owner-occupancy requirement for most unit types. The number you can build depends on your property.
- You generally choose between the state program and the local track, which have different rent control implications.
- Detached, attached, converted, and junior ADUs are all permitted, subject to zoning and buildable area requirements.
- Properties undergoing seismic retrofit work may qualify for additional ADUs.
- An ADU screening form and, often, a pre-application meeting with Planning, DBI, and Fire confirm requirements before you apply.
- Rent control status and deed restrictions can limit your flexibility later, so learn them before you design.
Talk to an ADU professional about your San Francisco property
ADU rules in San Francisco overlap: planning code sections, state law, and building and fire standards. They also keep changing as the city and state revise housing policy.
Talk to a professional experienced with San Francisco’s ADU program before you pay for design or submit a permit application, so you know what is possible at your address.
