Building permits, zoning and land rules in San Francisco County, California

San Francisco County requires a separate building permit before a regulated building or structure is constructed, enlarged, altered, repaired, moved, improved, removed, converted or demolished, unless a specific code exemption applies¹. Starting permit-required work without approval triggers a special investigation before a permit can be issued¹¹. Applications filed since January 2026 use the 2025 California Codes and San Francisco amendments, with no grace period¹². California's owner-builder exemption can waive contractor licensing for qualifying work, but it does not waive building permits, inspections or occupancy approval⁷. Permitted work must remain accessible and exposed until DBI approves it¹¹. A building cannot be occupied, or its occupancy classification changed, until DBI issues the required final, amended or other use approval¹.

The Department of Building Inspection (DBI) approves plans and issues building permits for all construction throughout the City and County of San Francisco¹². DBI's public counter is at 49 South Van Ness Avenue, San Francisco¹²; reach DBI Customer Service at 628-652-3200 or dbicustomerservice@sfgov.org for building-permit and inspection questions¹². San Francisco publishes its Building Code fee schedule, but the charge depends on the project and permit type; plan review not covered by the main table costs $399 per hour with a one-hour minimum¹. Permitted work must stay visible until approval, and certain construction requires continuous inspection by special inspectors¹¹. DBI may require an inspection request at least one working day in advance¹.

San Francisco County has zoning on every parcel because the consolidated city and county has no unincorporated territory². The official maps label individual districts, and the Planning Code classifies uses as permitted, conditionally permitted or not permitted^2,13. New lots generally must be at least 20 feet wide and 1,200 square feet in area, with at least 16 feet of vehicle-access frontage; existing substandard lots may follow separate rules¹⁴. No countywide minimum dwelling size was confirmed: the documented 300-square-foot studio minimum applies only to HOME-SF units¹⁰. Height is also district-specific; an RH-2 dwelling generally cannot exceed 40 feet, with lower limits in specified sloping-lot conditions¹⁵. San Francisco's local ADU program operates citywide in districts permitting residential use, subject to property and program conditions¹⁶. Ask San Francisco Planning to identify the parcel's exact controls before designing¹⁷.

California's statewide OWTS policy governs septic systems in San Francisco County and authorizes local agencies to issue septic permits¹⁸. The framework covers systems that are constructed, replaced or undergo major repair, with different rules for ordinary systems, approved local programs, impaired-water areas and corrective action³. Subsurface disposal of domestic-strength wastewater is allowed only when the system satisfies the policy's permitting, monitoring and operating conditions¹⁹. We could not confirm which San Francisco agency issues a septic permit or a local inspection schedule, so ask the Department of Public Health before designing an off-grid sanitation system²⁰. Only 30.6% of county soils lack severe limits for a conventional drain field²¹. Production wells require a Public Health permit⁵, while monitoring wells and soil borings have a separate approval and inspection process²².

San Francisco prohibits using a house car, camper or trailer coach for human habitation on public streets and other public ways between 10:00 p.m. and 6:00 a.m.; that rule does not answer whether an RV may be occupied on private property⁸. We could not confirm a San Francisco rule allowing year-round RV occupancy on private land, so ask DBI and Planning before relying on an RV as a dwelling^12,17. California otherwise limits RV occupancy to the locations and conditions allowed for its classification⁹. A tiny home needs approval as a recognized structure type and approval for its location⁹. San Francisco did not adopt the state tiny-house appendix, and we could not confirm another complete local tiny-home occupancy path; a conventional ADU may be the clearer route on eligible residential property¹⁶.

1. Use the official zoning maps, then ask San Francisco Planning to confirm the parcel's use, setbacks, height and project-specific controls^13,17.
2. Decide whether the proposal uses the conventional dwelling, ADU or eligible small-subdivision path^16,23.
3. If the parcel is in a FEMA FIRM Flood Hazard zone and the project is new construction or costs more than 50% of the structure's market value, have a California-licensed engineer or architect prepare the required flood checklist²⁴.
4. File the building permit application with DBI under the current code cycle and budget from the published fee schedule^1,12.
5. Complete the Owner-Builder Declaration at permit issuance if you qualify, and obtain a Street Improvement Permit if the project changes a driveway^7,25.
6. Keep permitted work exposed, request inspections and secure DBI's final occupancy approval before use^1,11.

San Francisco County has 17,244 people per square mile and a typical home value around $1.4 million, so even a small build starts with an urban land market²¹. Confirm the parcel's legal lot status, zoning and vehicle frontage before buying; newly created lots generally need at least 20 feet of width, 1,200 square feet of area and 16 feet of frontage on a permanent vehicle-access right-of-way¹⁴. Check the FEMA FIRM zone because qualifying new construction or work costing more than 50% of the structure's market value triggers the Floodplain Management Ordinance, while property located only in the city's stormwater flood-risk zone does not trigger that ordinance²⁴. Confirm water and sewer service because we could not confirm a connection mandate for every private parcel⁴. San Francisco's hills vary sharply by neighborhood even though 70.6% of county land has a slope of 15% or less, so verify the lot's grade before planning foundations or access²¹. Typical property tax is about 0.7% of assessed value, with a median annual bill of about $9,412²¹.