Garage Conversion in San Francisco, CA: Cost, Permits & Rules (2026)

A garage conversion is usually the lowest-cost path to an ADU in San Francisco — $120,000-$300,000, versus $300,000-$550,000 for a new detached build — because the shell already exists.

Garage Conversion Cost in San Francisco

Converting an existing garage in San Francisco runs $120,000-$300,000. That's well under the $300,000-$550,000 typical cost of a ground-up detached ADU, because you're reusing the foundation, walls, and roof. The biggest variables are whether the slab and framing are sound, what utility/electrical upgrades are needed, and your finish level. Permit fees add Planning Department building-permit review (Fee Schedule effective August 29, 2025, revised June 15, 2026): new construction $3,502 under $100,000; $3,504 plus 3.855% of cost above $100,000 up to $499,999; $19,226 plus 1.230% above $500,000. Alteration or conversion: $504 under $10,000; $516 plus 5.274% above $10,000; $3,838 plus 3.524% above $50,000; $5,638 plus 3.855% above $100,000; back-check $366. DBI building permit (Building Code Table 1A-A, permits issued on or after July 12, 2026): plan review $1,617 plus $15.60 per $1,000 over $50,000, or $4,011 plus $13.31 per $1,000 over $200,000; permit issuance $677 plus $4.83 per $1,000 over $50,000, or $1,402 plus $4.21 per $1,000 over $200,000; plumbing, electrical, mechanical, Fire, Public Works and Public Health fees are extra (Table 1A-A note 1). SFUSD school facility fee $3.79 per sq ft of added habitable area (2026 Impact Fee Register). Worked example (our calculation, not a published figure): a $300,000 detached ADU pays about $11,214 to Planning plus $5,342 and $1,823 to DBI, roughly $18,400 before trade permits and school fees; DBI says City fees typically run 6-9% of construction cost. Fees are waived for permits that legalize units built without permits before January 1, 2020. A converted unit rents for about $3,000-$4,200/mo (1BR) in San Francisco.

The San Francisco Garage Conversion Permit Process

A garage-to-ADU conversion in San Francisco needs building permits even if the exterior is unchanged. Approval process: Both programs need a DBI building permit filed through the PermitSF portal with an ADU Screening Form (elect State/Hybrid or Local and sign the Rent Ordinance affidavit), a Permit Applicant and Authorized Agent form and the 60-day Tolling Declaration. State program (Planning Code 207.2): ministerial review, no CEQA, no Section 311 neighbor notice, no discretionary review, no appeal to the Board of Appeals (Ordinance 222-25), no design review except objective historic standards; a full-permit application is reviewed at a free virtual Permit Review Roundtable where DBI, Planning, Public Works, Fire and SFPUC deliver all comments in one meeting. Local program (207.1): at least 15 calendar days before applying, post a Notice of Addition of ADU and an owner's declaration in the building and mail them to every unit, file the declaration with the Rent Board (tenants have 30 days to object), then file a Project Application (PRJ) with Planning for in-house review and obtain a Planning Approval Letter before DBI will accept the building permit; Zoning Administrator waivers (207.1(g)) and, where the lot has rental units, a recorded Costa-Hawkins regulatory agreement. No Local-program ADU on a lot with an owner move-in eviction in the past 5 years or another no-fault eviction in the past 10 years (207.1(c)(2)) The review timeline is 60 days from a complete application under Gov. Code 66317 (SB 543, January 2026: deemed approved if the City does not act). DBI requires every ADU applicant to sign an Application Processing Time Tolling Declaration choosing either to pause the 60-day clock while revising plans or to keep it running, in which case DBI may deny the application if code compliance is not shown within 60 days and revised plans are due at least 10 business days before the deadline. Local-program projects add the 15-day tenant notice, a 30-day Rent Board objection window (up to 90 days more if a tenant objects) and Planning in-house review before the building permit is filed; DBI states that State-program full permits generally have a shorter review and issuance timeline than the Local program. The City publishes no average issuance times, with plan check: Electronic plan review in Bluebeam Revu with a required Back Check page. Plans must be stamped by a licensed design professional unless the home is wood-frame, under 2 stories plus basement, under 25 ft wide between bearing walls and under 25 ft tall (Information Sheet G-01). An ADU must be at least 220 sq ft with 7.5-ft ceilings in living and sleeping rooms, its own entrance, a rescue window in every bedroom and an exit path of no more than 125 ft to the street. Buildings with 3 or more units and a rear-yard sleeping room may need a fire alarm and ground-floor sprinklers; a fire flow study is required for new floor area, and street tree, Public Works right-of-way, Maher soil and construction-waste requirements can apply. Pre-approved plans: DBI runs a Pre-approved ADU Plans program in which building designers submit detached-ADU designs for a $2,408 flat review fee; approved designs are meant to be posted on DBI's site for owners to choose and have the designer adapt to their lot. As of September 19, 2026 DBI's page lists no approved designs. Pre-approved plans are drawn for 25-ft lots, are valid only for the current code cycle, cannot be used in slope-protection, landslide, liquefaction, Maher or flood zones, and still need site-specific plan check of Planning Code compliance, soils, fire separation, foundation and SFUSD fees; a separate tolling form applies to permits that use a pre-approved plan.

1. Confirm eligibility — ADUs are allowed in Any lot in a zoning district that allows residential use, including the RH, RM, RTO and RC districts and the Neighborhood Commercial and mixed-use districts, as long as the lot has an existing or proposed dwelling (Planning Code 207.1(b) for the Local program; 207.2(b) and (d)(2) for the State program). One Local-program limit: an ADU may not eliminate or reduce ground-floor retail space in a Neighborhood Commercial, Chinatown Community Business or Chinatown Visitor Retail district unless it is a Designated Child Care Unit (207.1(c)(12)). Confirm your district on the Property Information Map.
2. Prepare conversion plans — layout, egress windows, insulation, ventilation, smoke/CO detectors, plus a kitchen and bathroom.
3. Submit for plan check — Electronic plan review in Bluebeam Revu with a required Back Check page. Plans must be stamped by a licensed design professional unless the home is wood-frame, under 2 stories plus basement, under 25 ft wide between bearing walls and under 25 ft tall (Information Sheet G-01). An ADU must be at least 220 sq ft with 7.5-ft ceilings in living and sleeping rooms, its own entrance, a rescue window in every bedroom and an exit path of no more than 125 ft to the street. Buildings with 3 or more units and a rear-yard sleeping room may need a fire alarm and ground-floor sprinklers; a fire flow study is required for new floor area, and street tree, Public Works right-of-way, Maher soil and construction-waste requirements can apply.
4. Pull permits and build — fees run Planning Department building-permit review (Fee Schedule effective August 29, 2025, revised June 15, 2026): new construction $3,502 under $100,000; $3,504 plus 3.855% of cost above $100,000 up to $499,999; $19,226 plus 1.230% above $500,000. Alteration or conversion: $504 under $10,000; $516 plus 5.274% above $10,000; $3,838 plus 3.524% above $50,000; $5,638 plus 3.855% above $100,000; back-check $366. DBI building permit (Building Code Table 1A-A, permits issued on or after July 12, 2026): plan review $1,617 plus $15.60 per $1,000 over $50,000, or $4,011 plus $13.31 per $1,000 over $200,000; permit issuance $677 plus $4.83 per $1,000 over $50,000, or $1,402 plus $4.21 per $1,000 over $200,000; plumbing, electrical, mechanical, Fire, Public Works and Public Health fees are extra (Table 1A-A note 1). SFUSD school facility fee $3.79 per sq ft of added habitable area (2026 Impact Fee Register). Worked example (our calculation, not a published figure): a $300,000 detached ADU pays about $11,214 to Planning plus $5,342 and $1,823 to DBI, roughly $18,400 before trade permits and school fees; DBI says City fees typically run 6-9% of construction cost. Fees are waived for permits that legalize units built without permits before January 1, 2020; then framing, electrical, plumbing, and final inspection.

No Replacement Parking Required

No. California law (AB 68 / Gov Code §66314) prohibits cities from requiring replacement parking when you convert or demolish a garage to build an ADU — so you do not need to add a parking space anywhere on the lot. Owner-occupancy is not required, so you can rent the converted unit out.

The JADU Option for an Attached Garage

If your garage is attached to the house, you can convert it into a junior ADU (JADU) — capped at 500 sq ft of interior livable space, inside the walls of an existing or proposed single-family home including an attached garage (Gov. Code 66313 and 66333(d); Planning Code 207.2(h)). A JADU exists only in the State program on a single-family lot; the Local program has no JADU. It needs at least an efficiency kitchen (cooking appliance, counter and cabinets) and its own entrance, and may be combined with one converted and one detached ADU (Bulletin No. 3) and built within the existing walls. JADUs are cheaper and faster to permit than a full ADU, though they may share sanitation with the main home. A full ADU gives you more size and a separate unit; a JADU is the budget route.

San Francisco Garage Conversion FAQ