How to add a backyard ADU in San Francisco in 2026: the State vs. Local program, size and height limits, fees, the 60-day permit path, and rent rules.
Most San Francisco homeowners can add a detached backyard ADU. Under the city's State ADU Program you need no parking, and the city must act within 60 days of a complete application.
Which San Francisco ADU program should you use?
San Francisco runs two ADU programs, and you can't mix them on one project. Most backyard ADUs use the State Program.
State Program: a decision within 60 days, no neighborhood notice, up to 850 sq ft (1,000 with 2+ bedrooms). Local Program: more units on some lots, but a slower review, and rent control can apply.
Will an ADU fit on my San Francisco lot?
Many 25-foot lots work. If the backyard is only reachable through the house, the home goes in by crane.
The city sets a 220 sq ft minimum, with 7.5-ft ceilings in living and sleeping areas. A new ADU that replaces an old shed or garage in the same footprint needs no setback at all.
How much does an ADU cost in San Francisco?
SF's building department says adding a unit typically costs at least $125,000 in material and labor, plus about 10% for design and 6% to 9% in city fees. Our price is one all-in number.
Launch price through Dec 31, 2026. Everything from permits to keys. Not included: solar, furniture, upgrades. What's included
How long does an ADU permit take in San Francisco?
The city has 60 days to act once your application is complete. A typical Bay Modular project takes 4 to 6 months in total, from first call to keys, permits included.
Choose a full permit, not a site permit. Only full permits for a State Program ADU with no other construction qualify for DBI's Permit Review Roundtable, which "generally has a shorter review and issuance timeline."
San Francisco ADU FAQ
SF ADU rules in full›
San Francisco runs two ADU programs, and you can't mix them on one project. The city's in-law unit program (Ordinance 162-16) opened in 2016 to every zoning district that allows housing, and ordinances through 2025 have amended it.
State Program (most backyard ADUs): ministerial review, a decision within 60 days, no neighborhood notice. Up to 850 sq ft for a studio or one-bedroom and 1,000 sq ft for two or more bedrooms; 18 ft tall on a single-family lot (16-18 ft on multi-family lots); 4 ft from side and rear lines. Local Program: Planning Code waivers and more units on some lots, but a slower in-house Planning review first.
The minimum is 220 sq ft, with 7.5-ft ceilings in living and sleeping areas. Additional parking is not required, and converting a garage doesn't trigger replacement parking. Your plans must show where three 32-gallon garbage, recycling, and compost bins will be stored out of sight from the street. A new ADU that replaces an old shed or garage in the same footprint needs no setback.
Sources: SF Planning Director Bulletin No. 3 (June 2026); SF.gov, Design an ADU that meets City codes.
Fees and what our price covers›
Impact fees up to 750 sq ft: $0. City plan check and permit fees: 6-9% of cost. Street tree: $2,590 per missing tree (a 30-ft lot needs two, so up to $5,180; waiver for ADUs expected end of Oct 2026). School fee for ADUs over 500 sq ft: up to $5.38/sq ft.
Our all-in price includes: lot check, design, permit drawings; city permit and plan-check fees; site prep and foundation; the home built in our Lathrop factory; delivery, crane, water, sewer, power hookups; kitchen, bath, flooring, lighting; final inspection and a project manager. Not included: solar panels, furniture and decor, landscaping outside the work area, upgrades beyond standard finishes, and SF extras like street trees if your lot needs them. Your price is fixed in the contract after we check your lot.
Our 256 sq ft Small Studio has 224 sq ft of living space inside. Our 120 sq ft Backyard Studio is below SF's 220 sq ft minimum, so in SF it works as an office, not a rental.
Sources: SF.gov ADU permit and street tree pages (checked Oct 24, 2026); Gov. Code § 66311.5; OPSC 2026 rate. See our full price breakdown and California ADU cost guide.
Permit steps and factory-built›
1. Free lot check (rules, crane access, utilities). 2. Design and plans (model, finishes, drawings). 3. City permit at the DBI roundtable review, 2-6 months. 4. Crane day: the home is set on the foundation in 1 day. 5. Inspection and keys (hookups, final sign-off).
Before you file: look up zoning and existing units on the SF Property Information Map. Then clear a fire flow study for new construction, street trees, right-of-way permits and, if you'll move 50+ cubic yards of soil in a Maher area, a Public Health review. The full permit needs plans stamped by a design professional, the ADU screening form and Title 24 energy forms. DBI also holds pre-application meetings (Administrative Bulletin AB-028). Watch out: SF Planning warns of a phishing scam sending fake permit payment requests. Confirm with your assigned planner before paying.
We're a licensed California contractor (CSLB #1112074) and build each home from steel modules in our own factory in Lathrop to HCD-approved plans (HCD #1585366). Steel doesn't burn the way wood framing does, and termites can't eat it. What factory-built means · Tour the factory
Renting, JADUs and condo sales›
You can rent an ADU for terms longer than 30 days, and you don't have to live on the property (Gov. Code § 66315). It depends on the program: state law keeps some State Program ADUs out of rent control, while Local Program ADUs that get waivers on a lot with rental units go under rent control by agreement.
Tenants in the main building? For Local Program ADUs, post a Notice of Addition and a Declaration at least 15 days before applying and file them with the Rent Board; tenants then have 30 days to object. Talk to the Rent Board before you sign a lease. See our guide to renting out your ADU and the rental and ROI calculator.
A JADU is up to 500 sq ft carved out of your house, with at least an efficiency kitchen. If it shares a bathroom with the main house, you must record a deed restriction requiring the owner to live in the JADU or the house.
Since May 1, 2025, one State Program detached ADU on a single-family lot can be sold separately as a condo, when the lot has four or fewer existing units and the ADU application was filed on or after that date. Talk to a real estate attorney before you count on it.
Can I Airbnb my ADU in San Francisco?›
No. SF Planning says ADUs aren't eligible for the city's Short-Term Rental program, and State Program ADUs must be rented for more than 30 days.
Can a prefab ADU go in a backyard with no side access?›
Often it can, by crane over the house, with a Public Works street space permit. Whether it works on your lot depends on crane reach, wires, and street space, which is what a lot assessment checks.
Who builds ADUs in San Francisco?›
General contractors with an architect, design-build ADU firms, and factory-built ADU companies like Bay Modular. Check the contractor's CSLB license, who files the DBI permit, and get one all-in price in writing before you sign.
We check your lot against SF's two programs, tell you which model fits, and give you an all-in price. You decide after that.
About Julia B. Julia B is a marketing specialist at Bay Modular, a licensed California ADU builder (CSLB #1112074) with its own factory in Lathrop. She writes about what ADUs really cost and how to avoid surprises.
Sources, city contacts, more guides
More: Models · Building in San Francisco · California ADU cost · San Mateo · Palo Alto guides
Sources
- San Francisco Planning, Accessory Dwelling Units (programs, FAQ, legislative history). Accessed October 8, 2026.
- San Francisco Planning, Planning Director Bulletin No. 3: State ADU Program, updated June 2026.
- SF.gov (DBI), Get a building permit for an ADU and Learn about the Permit Review Roundtable. Accessed October 8, 2026.
- SF.gov, Design an ADU that meets City codes, Check if you can add new ADUs, and Pre-approved ADU plans. Accessed October 8, 2026.
- SF.gov (Public Works), Check our street tree rules for your ADU (checked October 24, 2026); San Francisco Public Works, Street Space permits. Accessed October 8, 2026.
- SF.gov (Rent Board), Accessory Dwelling Units (ADUs). Accessed October 8, 2026.
- California Department of Housing and Community Development, ADU Handbook, March 2026 (Gov. Code §§ 66311.5, 66315, 66317, 66322, 66333).
- Office of Public School Construction, Developer Fee History, Level 1 maximum adopted January 28, 2026.
- Bay Modular Pricing & Financing, October 2026.
Sources checked October 8-24, 2026.
SF Planning ADU team: cpc.adu@sfgov.org, Planning Counter 628-652-7300 · Permit Center: 49 South Van Ness Avenue, 2nd floor · DBI Roundtable: sfplanreview@sfgov.org · Rent Board: rentboard@sfgov.org · Public Works street space: streetspace@sfdpw.org
General information, not legal, tax, or financial advice. Confirm details for your address with SF Planning and DBI.
