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Permit guides
ADU Permits in South San Francisco: a Homeowner's Guide
South San Francisco spells out its ADU fees and requirements in unusual detail — including a sewer video most applicants don't expect.
Last updated October 2026. Rules change; always confirm current requirements with the city before you build.
Who handles your permit
ADU permits in South San Francisco run through the city's Economic & Community Development Department, which publishes a detailed ADU handout covering fees, parking, occupancy, and use restrictions. The Planning Division provides the deed-restriction form you'll need to file. Utility and sewer questions go through Engineering.
What you can build
1,200 sq ftMax for a detached ADU under state law
~10%Building permit fees run about 10% of project valuation, including plan check and MEPs
$3.79 / sq ftSchool district fees for ADUs over a certain size, paid directly to the district
30 daysMinimum rental term — ADUs can't be rented for shorter stays
Deed restrictionMust be filed acknowledging occupancy, ownership, and size restrictions
4 ftMinimum side and rear setbacks for detached ADUs
For Junior ADUs, the owner must occupy either the primary residence or the JADU. No ADU or JADU can be sold separately from the primary dwelling.
The fees, spelled out
South San Francisco is unusually transparent about costs. Building permit fees run approximately 10% of the valuation, including plan check and mechanical/electrical/plumbing review. Sewer capacity charges apply only when the ADU is built together with a new dwelling, proportionate to size or drainage fixture units. Then the items people miss:
- Sewer video: required on most ADUs — $78 to review the video, $79 for the compliance certificate. If the lateral fails, replacement averages $10,000–$20,000.
- Encroachment permit: roughly $332 permit fee plus $160/hr inspection and a $2,000 deposit.
- School fees: $3.79 per square foot for ADUs over a certain size, paid to the school district, not the city.
What goes into the submittal
- Exterior entry is required for ADUs (JADUs may use an interior entry if sanitation facilities are shared)
- Deed restriction filed acknowledging occupancy, ownership, and size restrictions — get the form from Planning
- Parking: one space per ADU or per bedroom, whichever is less; tandem parking on a driveway counts
- Parking is waived near transit, in historic districts, for conversions, or near car-share — check which exemption fits your lot
- Utility connections: new or separate connections are only required for ADUs built with new dwellings, charged proportionate to size
Where applications usually get stuck
- The sewer video. It's the single most common budget surprise — a failed lateral turns a $157 inspection into a five-figure replacement.
- School fees. They're paid to the district, not the city, so they don't appear on the city's fee estimate — but they're real.
- Deed restriction paperwork. Simple, but it has to be filed correctly before the permit moves.
Not sure where to start? That's the part we do. We check your property against the requirements, coordinate the plans and specialists, and manage the submittal and corrections — one point of contact.