ADU Builders in San Francisco, CA (2026)

ADU builders in San Francisco typically quote $200,000-$450,000 for a new detached unit, or about $300-$500 per square foot, including design, permitting, and construction. A garage conversion runs $120,000-$250,000 and a prefab/modular ADU averages $150,000-$350,000. Add city permit and plan-review fees (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).) plus impact fees of MORE GENEROUS THAN STATE LAW — commercially the second-biggest correction. PC 207.2(j) waives impact fees for a State-Program ADU or JADU that is under 750 sq ft of Gross Floor Area, OR that is proposed on a lot with THREE EXISTING UNITS OR FEWER regardless of size. So on a typical SF single-family, duplex or triplex lot, a State-Program ADU pays NO impact fees even at 1,000 sq ft. Above those thresholds, fees are imposed proportionately to the gross floor area of the primary dwelling unit. CAVEAT TO FLAG: the Planning Code says 'Gross Floor Area' for the 750 threshold while Planning Director Bulletin No. 3 says 'interior livable space' — the code controls. SECOND CAVEAT: 207.2(j) is expressly limited to the State Program; PC 207.1 contains no parallel exemption, so Local-Program impact fees are unresolved.. Quotes for the same scope commonly vary 20-40% between builders, so collect at least three bids.

Look for a licensed contractor with completed ADU projects in San Francisco specifically — ADUs involve local zoning, setback rules, and utility connections that general remodelers may not have handled. Verify the license, ask for an ADU-specific portfolio and references, confirm they carry liability and workers' comp insurance, and get a written fixed-price or detailed bid. Submit a request below and we'll forward it to local ADU builders serving San Francisco for free quotes.

Most full-service ADU builders manage the permit process for you. In San Francisco the approval process is "TRUE ONLY OF THE STATE PROGRAM — must be split. STATE PROGRAM: ministerial; no CEQA; no Planning Code Sec. 311 neighborhood notification; no discretionary review; no subjective design review except historic-resource standards for ADUs under Gov. Code 66314; appeals prohibited under AB 1114 for permits filed on or after 1/1/2024; eligible for a free virtual Permit Review Roundtable with DBI, Planning, Public Works, SF Fire and SFPUC in one meeting. LOCAL PROGRAM: requires (a) a Notice of Addition of ADU plus declaration posted in the building and mailed/delivered to every unit including unauthorized units at least 15 CALENDAR DAYS before applying; (b) a declaration filed with the Rent Board under penalty of perjury regarding severance of housing services, which tenants may contest by petition within 30 calendar days; (c) a Project Application (PRJ) to Planning for In-House Review and a Planning Approval Letter BEFORE DBI will accept the building permit; (d) possible Historic Resource Review; (e) Zoning Administrator waivers under PC 207.1(g)/307(l); (f) a recorded Regulatory Agreement / Costa-Hawkins agreement where waivers are granted on a lot with Rental Units. BOTH: an ADU Screening Form must be filed with the permit application, on which the applicant elects State/Hybrid or Local and signs a Rent Ordinance affidavit. ELIGIBILITY BAR (Local only): no ADU where there was an owner move-in eviction within 5 years or another no-fault eviction within 10 years." with a typical review timeline of 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.'. Confirm in writing whether permit fees, plan check (Expedited plan check available), and impact fees are included in the bid or billed separately.

Plan for the permit review (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.' in San Francisco) plus construction. Most detached ADUs take 4-8 months of construction after permits are issued; garage conversions and prefab units are often faster. Ask each builder for a realistic schedule and what could delay it.