Everything homeowners ask about building an ADU in San Francisco — answered with 2026 data.
Yes, 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 in San Francisco, CA. The maximum size for a detached ADU is State program: 850 sq ft of gross floor area for a studio or 1-bedroom detached ADU and 1,000 sq ft for 2 or more bedrooms on a lot with a single-family home (Planning Code 207.2(c)(1) and (d)(5)(B); Ordinance 222-25 raised the streamlined cap above the 800 sq ft state floor, effective December 22, 2025). A detached ADU on a lot with an existing multifamily building has no maximum size (Planning Director Bulletin No. 3, June 2026). Local program: the same 850 / 1,000 sq ft caps for the one detached rear-yard ADU (207.1(c)(15)(B)). San Francisco measures gross floor area, not interior livable space. Attached ADUs can be up to State program. San Francisco has an ADU-friendliness score of 9/10. Check our full San Francisco ADU rules page for complete zoning details.
ADU construction in San Francisco typically costs $300,000-$550,000. The cost per square foot averages $350-$650. Garage conversions are more affordable at $120,000-$300,000, while prefab ADUs cost $180,000-$350,000. 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 to your budget. See our detailed San Francisco ADU cost guide.
Detached ADUs in San Francisco can be up to State program: 850 sq ft of gross floor area for a studio or 1-bedroom detached ADU and 1,000 sq ft for 2 or more bedrooms on a lot with a single-family home. Attached ADUs are limited to State program. Junior ADUs (JADUs) have a cap of 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). Maximum height is State program: 18 ft for a detached ADU on any lot with an existing or proposed dwelling, plus 2 ft for a roof pitch that matches the main house (20 ft total); 25 ft for an attached ADU (Planning Code 207.2(d)(9)). The 18 ft applies citywide with no transit-distance or multistory test. Local program: 16 ft for the detached rear-yard ADU (207.1(c)(15)(A)); a converted ADU has no height limit; other Local ADUs follow the district height limit and may not add a story, except a corner-lot detached garage may add one story within its footprint and a building in a seismic retrofit may be raised up to 3 ft (207.1(c)(5), (c)(7), (f)). You are allowed up to State program, single-family lot: one converted ADU plus one detached ADU plus one JADU, all on the same lot on a qualifying lot.
Rear setback: State program: 4 ft from the rear lot line for a new detached or attached ADU; no setback for an ADU within existing living space or an existing accessory structure, or one that replaces an existing structure in the same location and dimensions; for an ADU that is part of new construction the 4 ft applies only to the part outside the buildable area (Planning Code 207.2(d)(7)). Local program: 4 ft for the detached rear-yard ADU (207.1(c)(15)(A)); none for a conversion of existing space; otherwise the district rear yard applies, which is 30% of lot depth in RH, RM-1, RM-2 and RTO districts and 25% in other residential districts (Planning Code 134; ZA Bulletin 5, Sept. 2025), unless the Zoning Administrator waives it for an ADU in an existing building (207.1(g)). Side setback: State program: 4 ft from each side lot line for a new detached or attached ADU; none for a conversion or a same-footprint replacement; for new construction the 4 ft applies only to portions outside the buildable area (Planning Code 207.2(d)(7)). Local program: 4 ft for the detached rear-yard ADU (207.1(c)(15)(A)); conversions need none; other Local ADUs follow the district, and side yards are required only in RH-1(D) districts (Planning Code 133; ZA Bulletin 5). Building Code fire-separation and opening-protection rules still apply near a lot line. Front setback: The zoning district's front setback applies (Planning Code 132), but the City may not apply front setback, lot coverage, floor area ratio, open space or minimum lot size rules in a way that prevents a State-program ADU of 800 sq ft or less and 16 ft or less with 4-ft side and rear setbacks (207.2(d)). At least half of a required front setback must remain permeable and 20% planted (sf.gov ADU design page). The Local program has no front-setback waiver; its waivers cover density, bicycle parking, rear yard, exposure and open space only (207.1(g)). Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
None. No off-street parking is required for an ADU or JADU under either program, and when a garage, carport or covered parking space is demolished or converted for an ADU the lost spaces need not be replaced; the garage demolition permit is issued together with the ADU permit (Planning Code 207.2(d)(8); sf.gov ADU design page). Under the Local program, removing a tenant's garage, storage or laundry is a severed housing service that needs a just cause or the tenant's written consent (207.1(c)(3)-(4); Rent Ordinance 37.2(r)), and on-site laundry may not be removed unless replaced with equal capacity (207.1(c)(13)). Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Not required for any ADU under either program (Planning Code 207.1 and 207.2 impose none; Gov. Code 66315). A JADU that shares a bathroom with the main house requires a recorded deed restriction with owner-occupancy in either the JADU or the main home; a JADU with its own bathroom has no owner-occupancy requirement (Gov. Code 66333(b) as amended by AB 1154, effective January 1, 2026; Bulletin No. 3). Note that owner-occupancy rules vary by state law — California and several other states have eliminated this requirement for standard ADUs.
The ADU permit review timeline in San Francisco is typically 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. 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 availability: 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.
Average ADU rental income in San Francisco: 1-bedroom units rent for $3,000-$4,200/month, 2-bedroom units for $3,700-$5,000/month. Short-term rentals: No. Expected ROI: 6-8% gross rental yield on a $300,000-$550,000 detached build at $3,000-$4,200/mo, before taxes, vacancy and financing; a $120,000-$300,000 conversion yields more.
The minimum lot size for an ADU in San Francisco is No minimum lot size. Eligibility turns on the district allowing residential use and the lot having an existing or proposed dwelling (Planning Code 207.1(b), 207.2(b)); a minimum-lot-size rule may not be used to block an 800 sq ft, 16 ft ADU with 4-ft setbacks (207.2(d)). DBI's pre-approved plans are drawn for the standard 25-ft-wide lot. This applies to detached ADUs — garage conversions and JADUs may have different or no lot size requirements.
Garage conversions are one of the most popular and affordable ADU options. In San Francisco, a garage conversion typically costs $120,000-$300,000. The key advantages are lower cost (no foundation work), potential setback exemptions, and faster permitting. Read our complete garage conversion guide.
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