Everything homeowners ask about building an ADU in San Francisco — answered with 2026 data.
Yes, ADUs are allowed in MORE GENEROUS than our list. ADUs are allowed on ANY lot in a zoning district that allows residential use — including mixed-use and commercial districts, not just the RH/RM/RTO family. PC 207.1(b) applies the Local Program to 'all lots located within the City and County of San Francisco in areas that allow residential use'. One SF-specific exclusion worth stating: PC 207.1(c)(12) bars an ADU in a Neighborhood Commercial District or the Chinatown Community Business or Visitor Retail Districts if it would eliminate or reduce ground-story retail space, unless it is a Designated Child Care Unit. in San Francisco, CA. The maximum size for a detached ADU is 850 sq ft gross floor area for a detached ADU with one bedroom or less; 1,000 sq ft for two or more bedrooms. Same cap in BOTH programs (State: PC 207.2(c)(1) and (d)(5)(B); Local: PC 207.1(c)(15)(B)). Exception: a detached ADU on a lot with an existing multifamily building under the State Program has NO maximum size. NOTE: SF measures this as GROSS FLOOR AREA, not interior livable space.. Attached ADUs can be up to MORE GENEROUS THAN OUR PAGE SAYS. 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 $200,000-$450,000. The cost per square foot averages $300-$500. Garage conversions are more affordable at $120,000-$250,000, while prefab ADUs cost $150,000-$350,000. Permit fees add Replace the guessed range with SF's own published figures. DBI's own estimate: 'City fees range from 6-9% of construction costs' (and architects/engineers about 10%; at least $125,000 in material and labor for a new unit). PLANNING development application fee (Fee Schedule eff. 8/29/2025, rev. 6/15/2026) — New Construction: $3,502 flat under $100k; $3,504 base + 3.855% of cost above $100,000 in the $100k-499,999 band; $19,226 + 1.230% above $500,000. Alteration/Change of Use (garage or interior conversion): $504 under $10k; $516 + 5.274% above $10,000; $3,838 + 3.524% above $50,000; $5,638 + 3.855% above $100,000. Neighborhood notification $121 + $4.25/envelope; permit-revision back check $366. DBI building permit fees are TWO separate charges under SF Building Code Table 1A-A (amended Ord. 112-26, eff. 7/12/2026) — Plan Review: $1,671 + $15.60 per $1,000 over $50,000 ($50k-200k band), $4,011 + $13.31 per $1,000 over $200,000 ($200k-500k band); Permit Issuance: $677 + $4.83 per $1,000 ($50k-200k), $1,402 + $4.21 per $1,000 ($200k-500k). Table 1A-A note 1 states these exclude Public Works, Planning, Fire, Public Health and plumbing/electrical/mechanical permit fees. Add SFUSD school facility fees (calculated by DBI staff), SFPUC and Public Works right-of-way permits. OUR WORKED EXAMPLE (label as our calculation, not a published number): a $300,000 detached ADU = Planning $11,214 + DBI plan review $5,342 + DBI issuance $1,823, roughly $18,400 before trade permits and school fees — about 6% of construction cost, consistent with DBI's 6-9%. FEE WAIVER: building permit fees are waived for permits granting legal status to dwelling units built without permits, for activities prior to 1/1/2020 (Board Ord. 150571). to your budget. See our detailed San Francisco ADU cost guide.
Detached ADUs in San Francisco can be up to 850 sq ft gross floor area for a detached ADU with one bedroom or less; 1,000 sq ft for two or more bedrooms. Same cap in BOTH programs. Attached ADUs are limited to MORE GENEROUS THAN OUR PAGE SAYS. State Program. Junior ADUs (JADUs) have a cap of 500 sq ft of interior livable space — correct, adopts the state definition. Add the SF-specific caveat: a JADU exists ONLY in the State Program (single-family buildings). The Local Program offers no JADU. A JADU may be combined with a Detached ADU and a Converted ADU.. Maximum height is MORE GENEROUS. State Program (PC 207.2(d)(9)): detached ADU up to 18 FEET on any lot with an existing or proposed dwelling, plus 2 additional feet to accommodate a roof pitch aligned with the primary dwelling (20 ft total); attached ADU up to 25 feet. SF grants the 18 ft with NO transit-proximity or multistory-multifamily condition. Local Program (PC 207.1(c)(15)(A)): detached rear-yard ADU limited to 16 feet; converted ADUs have no height limit; otherwise height follows the zoning district and no vertical addition is allowed except in the limited cases in 207.1(c).. You are allowed up to SUBSTANTIALLY MORE GENEROUS — this is the headline correction. STATE PROGRAM, single-family lot: 1 Detached + 1 Converted + 1 JADU, all combinable = up to 3 new units on a qualifying lot.
Rear setback: 4 ft is right for a NEW detached structure, but wrong as a blanket rule. State Program (PC 207.2(d)(7)): NO setback is required for an ADU within an existing living area or existing accessory structure, or one that replaces an existing structure at the same location and dimensions; a setback of no more than 4 ft applies otherwise; and for new construction the 4 ft applies only to portions outside the buildable area. Local Program: 4 ft for the detached rear-yard ADU (207.1(c)(15)(A)); but converted space needs NO setback and other Local-Program ADUs must meet the underlying zoning district rear yard (in SF RH districts typically 25% of lot depth, far more than 4 ft) unless the Zoning Administrator grants a rear-yard waiver under 207.1(g).. Side setback: Same treatment as rear: 4 ft from side lot lines for a new detached ADU under both programs; zero for conversions and same-footprint replacements; and under the State Program the 4 ft applies to new construction only for portions outside the buildable area. Local-Program non-detached ADUs follow the zoning district.. Front setback: Broadly right, but incomplete. Under the State Program PC 207.2(d) bars the City from applying lot coverage, FAR, open space, FRONT SETBACK or minimum lot size rules in a way that would prevent an ADU of 800 sq ft or less, 16 ft or less, with 4 ft side and rear setbacks. So the zone's front setback applies but cannot be used to block a conforming small ADU. Under the Local Program the front setback applies per the zoning district and is NOT among the waivers available under PC 207.1(g) (which cover density, bicycle parking, rear yard, exposure and open space only).. Note that garage conversions may be exempt from setback requirements if the existing structure is already within the setback area.
Value stands, but add the SF-specific trap. Neither PC 207.1 nor PC 207.2 imposes any parking requirement on an ADU, and PC 207.2(d)(8) expressly bars requiring replacement spaces when a garage, carport or covered parking structure is demolished or converted for an ADU. HOWEVER: under the Local Program an ADU may not sever a tenant's 'housing service' — which SF Planning states includes a garage, laundry room and storage — without just cause, and PC 207.1(c)(13) bars removing on-site laundry unless replaced with equal number/capacity. So there is no parking minimum, but taking an existing tenant's garage can block the project.. Many cities and states have been relaxing ADU parking requirements in recent years. In California, no additional parking is required for ADUs near transit.
Correct for ADUs — neither PC 207.1 nor PC 207.2 imposes owner occupancy, matching Gov. Code 66315. Add the JADU exception SF actually applies: if a JADU SHARES sanitation facilities with the main residence, the owner must record a deed restriction that includes an owner-occupancy requirement in either the JADU or the primary home. A JADU with its own bathroom carries no owner-occupancy requirement.. 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 — but SF requires every ADU applicant to sign an 'Application Processing Time Tolling Declaration Form' electing either to TOLL (pause) the 60-day clock while revising plans, or to hold the City to it. If the applicant declines tolling, DBI may DENY the application if code compliance cannot be established within 60 days, and revised plans must be resubmitted at least 10 business days before the period ends. Most applicants therefore toll and the real elapsed time exceeds 60 days. Add the Local-Program pre-clock: 15 calendar days of posted notice before filing, a Rent Board declaration with a 30-day tenant petition window (Rent Board targets transmitting a determination within 90 calendar days of a petition), then Planning In-House Review and a Planning Approval Letter — all before the building permit is filed. SF states State-Program full permits 'generally has a shorter review and issuance timeline than the Local program.'. Plan check: Expedited plan check available. Pre-approved plans availability: MISLEADING AS WRITTEN — rewrite. DBI runs a Pre-approved ADU Plans program, but it is a program for BUILDING DESIGNERS to submit designs for pre-approval, not a homeowner catalogue. Verified terms: a $2,408 flat fee per plan submitted for pre-approval (a widely repeated $1,519 figure is stale); plans 'should be designed for 25 ft lots'; pre-approval 'is only valid during the current code cycle'; pre-approved plans CANNOT be used in slope protection areas, landslide and liquefaction zones, Maher Zones or flood zones; and site-specific plan check is still required (Planning Code compliance, soils report and site survey, fire separation distance, foundation design, SFUSD fees, tree removal, drainage). Submissions go to dbi.preapprequests@sfgov.org and DBI schedules a Permit Review Roundtable. Do NOT claim it 'saves 2-3 months on design' — nothing on the city's pages supports a time saving. I found NO published catalogue of pre-approved plans; SF Planning's ADU page, Planning Director Bulletin No. 3 and the Local ADU Program Chart do not mention the program at all..
Average ADU rental income in San Francisco: 1-bedroom units rent for $2,200-$3,200/month, 2-bedroom units for $2,800-$4,000/month. Short-term rentals: Not allowed — SF ADUs and JADUs are ineligible for the Short-Term Rental program; minimum 30-day rentals only. Expected ROI: 5-8% annual return.
The minimum lot size for an ADU in San Francisco is No minimum lot size — correct, SF adopts the state floor. PC 207.2(d) expressly forbids the City from imposing a minimum lot size that would prevent an 800 sq ft / 16 ft / 4 ft-setback ADU, and PC 207.1 imposes no lot-size minimum. Eligibility instead turns on the lot being in a district that allows residential use and containing an existing or proposed dwelling.. 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-$250,000. 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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