How much does an ADU cost in San Francisco?

Most detached SF ADUs land between $375K and $550K all-in. Garage conversions typically run $200K–$310K. SFPUC connection fees and tight site access push costs above other Bay cities.

State ADU Law or SF Local Program — which track?

State ADU Law is faster (ministerial, no 311 notification) but caps the unit count. SF Local allows more units in qualifying multifamily but adds Section 311 + Planning review. We pick the track during feasibility based on building type and unit goal.

Will my ADU trigger Section 311 neighborhood notification?

On the SF Local Program track, almost always. On State ADU Law track, only if the project includes exterior changes visible from a public right-of-way. We design to stay inside the state track when timeline matters.

Can I build an ADU in a rent-controlled building?

Yes, adding ADUs is allowed and often encouraged. What's not allowed is demolishing or substantially altering an existing rent-controlled unit. We map all existing units before any design work begins.

How long does DBI plan check actually take?

8–14 weeks is typical. Pre-application meetings cut down on round-trip corrections. Complete, well-documented packages move faster than the average.

Does the soft-story retrofit ordinance affect my building?

If your building is on the MSSRP list (pre-1978, wood-frame, 3+ stories, 5+ units), yes — the retrofit is typically permitted alongside the ADU on a coordinated inspection schedule.

Bay Area · city profile

ADU permits in San Francisco

Typical timeline

SF Department of Building Inspection (DBI) + Planning: 14–22 weeks for a typical ADU; longer with neighbor notification.

What changes about the permit here

San Francisco permits are the slowest in our Bay Area service area, but they're predictable once you pick the right track. State ADU Law gives ministerial approval at 60 days from a complete submittal. The SF Local Program is more flexible (allows unlimited ADUs in some multifamily buildings) but adds Section 311 neighborhood notification and Planning review on top of DBI. The schedule variables are which track you choose, whether exterior changes trigger 311, and the DBI queue.

State ADU Law track: ministerial 60-day review, one detached + one JADU per single-family lot.
SF Local Program: allows unlimited ADUs in some buildings but triggers Section 311 neighborhood notification (30 days).
DBI plan check queue: typically 8–14 weeks; pre-application meetings shorten the round-trip.
Rent Ordinance: pre-1979 multifamily units cannot be demolished without invoking the Ellis Act or Costa-Hawkins — we map existing units before drawing.
Mandatory Soft-Story Retrofit Program (MSSRP) on pre-1978 wood-frame buildings of 3+ stories and 5+ units.

On-the-ground notes

SF runs two ADU tracks — State ADU Law (faster) and SF Local Program (slower, but allows more units in some buildings).
Neighborhood Notification (Section 311) adds 30 days to most projects with exterior changes.
Rent control applies to most pre-1979 multifamily — adding ADUs is allowed but demolition is not.
DBI plan check queue is the most common delay; pre-app meetings shorten the round-trip.

Cost ranges (2026)

Detached new-build: $550–$750/sqft
Garage conversion: $325–$475/sqft

Highest Bay Area construction cost — small lots, narrow streets, parking impossible.
Hillside / downslope lots (Diamond Heights, Twin Peaks, Bernal Heights east) add $40–150k in retaining and access.
SFPUC water + sewer connection fees are the highest in the region.
Soft-story retrofit pairing on a multifamily building can add $80–200k tied to the ADU permit.

Zoning highlights

RH-1, RH-2, RH-3, RM zones — state ADU law applies across all residential zones.
RC, NCT, Mission Dolores SUD — neighborhood commercial / mixed-use overlays add design standards.
Coastal Zone applies to the Ocean Beach / Sunset / Richmond strip.
Rent Ordinance (Chapter 37) caps demolition of pre-1979 units.

Stage-by-stage timeline

Survey + design + pre-app · 4–8 weeks
DBI pre-app shortens later round-trips.
Section 311 notification (if triggered) · 4–5 weeks
Skip on State ADU Law track with no exterior change.
DBI + Planning plan check · 8–14 weeks
Queue is the single biggest variable.
Construction · 20–30 weeks
Small lots, narrow access, weather sensitivity.

San Francisco, in short

How much does an ADU cost in San Francisco?: Most detached SF ADUs land between $375K and $550K all-in. Garage conversions typically run $200K–$310K. SFPUC connection fees and tight site access push costs above other Bay cities.
State ADU Law or SF Local Program — which track?: State ADU Law is faster (ministerial, no 311 notification) but caps the unit count. SF Local allows more units in qualifying multifamily but adds Section 311 + Planning review. We pick the track during feasibility based on building type and unit goal.
Will my ADU trigger Section 311 neighborhood notification?: On the SF Local Program track, almost always. On State ADU Law track, only if the project includes exterior changes visible from a public right-of-way. We design to stay inside the state track when timeline matters.
Can I build an ADU in a rent-controlled building?: Yes, adding ADUs is allowed and often encouraged. What's not allowed is demolishing or substantially altering an existing rent-controlled unit. We map all existing units before any design work begins.
How long does DBI plan check actually take?: 8–14 weeks is typical. Pre-application meetings cut down on round-trip corrections. Complete, well-documented packages move faster than the average.
Does the soft-story retrofit ordinance affect my building?: If your building is on the MSSRP list (pre-1978, wood-frame, 3+ stories, 5+ units), yes — the retrofit is typically permitted alongside the ADU on a coordinated inspection schedule.

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