Accessory Structures in San Francisco, CA

If you live in San Francisco or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. San Francisco has 5 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Garage Conversions

San Francisco lets homeowners convert an existing garage into a legal accessory dwelling unit under the Planning Code's Local ADU Program, subject to density and tenant-protection conditions.

Key details: Governing section: Planning Code Sec. 207.1. Where ADU may sit: Built envelope of existing garage. Eviction lookback: 5-10 years, just-cause dependent. Prior filing required: Rent Board housing-services declaration.

Building without Planning/DBI permits triggers a Planning Code enforcement notice and DBI stop-work order; ADUs tied to a within-10-years no-fault eviction are denied approval outright under Sec. 207.1(c)(2).

ADU Rules

San Francisco's Local ADU Program lets homeowners citywide build one accessory dwelling unit on lots with four or fewer units, with no cap on lots that already have more, garages included.

Key details: Governing section: Planning Code § 207.1. ADU limit (≤4 units): one ADU permitted. ADU limit (>4 units): no numeric cap. Garage conversion: allowed within built envelope. Applies to: all residential lots citywide.

The Planning Department will deny an ADU application under this program if a tenant was evicted from the unit under Administrative Code § 37.9 within the preceding five or ten years, depending on the eviction ground.

ADU Impact Fees

San Francisco charges no impact fees on ADUs and JADUs under 750 square feet, or on any ADU proposed on a lot with three or fewer existing units, per Planning Code § 207.2(j).

Key details: Governing section: Planning Code § 207.2(j). Fee waiver size: under 750 sq ft. Fee waiver by lot: 3 or fewer existing units. Other ADUs: fee prorated by floor area.

ADUs that exceed 750 square feet on lots with four or more existing units are not exempt; the city collects an impact fee proportional to the ADU's Gross Floor Area at permit issuance.

If you are coming from a city with tighter rules, you will find San Francisco gives residents more flexibility on adu impact fees.

ADU Rental Restrictions

San Francisco ADUs and JADUs built under Planning Code § 207.2 may be rented under the Rent Ordinance, but the lot generally cannot be subdivided to sell the unit separately.

Key details: Governing section: Planning Code § 207.2(g). Renting allowed: yes, under Rent Ordinance. Separate sale/condo: prohibited by default. Exception: Gov. Code § 66341 or § 207.4.

A subdivision map application that would allow separate sale or financing of an ADU or JADU outside the § 66341 or § 207.4 exceptions is not eligible for approval under § 207.2(g).

Compared to other cities, San Francisco takes a harder line on adu rental restrictions. The enforcement and penalty structure reflects that.

Shed & Carport Rules

A one-story detached shed or similar accessory structure up to 120 square feet does not need a building permit in San Francisco, though the structure can still be regulated under Section 710A.

Key details: Permit-exempt size: Up to 120 sq ft. Structure type: One-story detached accessory. Other rules: May still apply (Sec. 710A). Over threshold: Building permit required.

Building a shed or accessory structure over the 120-square-foot threshold without a building permit is unpermitted construction, subject to Department of Building Inspection notices of violation, stop-work orders, and after-the-fact permit penalties.

If you are coming from a city with tighter rules, you will find San Francisco gives residents more flexibility on shed & carport rules.

The Bottom Line

Compared to many U.S. cities, San Francisco gives residents more room on accessory structures. 2 of the 5 rules here are rated permissive. But permissive does not mean unregulated. There are still requirements, and the city does enforce them when violations are reported.

These rules come from San Francisco's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.