Accessory Structures in San Francisco, CA: What Residents Actually Need to Know

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 6 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Tiny Homes

San Francisco allows tiny homes as Accessory Dwelling Units under state ADU law (Gov Code 65852.2) and SF Planning Code Section 207. Movable tiny homes on wheels qualify as ADUs under AB 2421 if permanently sited with utilities and permits. Standalone 'tiny house' residences are otherwise restricted.

Key details: undefined: undefined. undefined: undefined. undefined: undefined. undefined: undefined. undefined: undefined.

Specific penalty amounts for this ordinance are not published in a publicly accessible fine schedule. Contact [San Francisco code enforcement](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?sectionNum=65852.2.&lawCode=GOV) directly for current fines, enforcement procedures, and hearing options.

ADU Rules

San Francisco actively encourages Accessory Dwelling Units (ADUs) under both a State Program (governed by Cal. Gov. Code 65852.2 / 65852.22) and a Local Program (Planning Code Sec. 207 / 209). State law mandates ministerial (non-discretionary) approval within 60 days. The City recognizes four ADU types: Converted, Attached, Detached, and Junior ADU (JADU, up to 500 sq ft within an existing single-family structure). ADUs cannot be used as short-term rentals and generally cannot be sold separately from the primary dwelling.

Key details: undefined: undefined. undefined: undefined. undefined: undefined. undefined: undefined. undefined: undefined.

ADUs used as short-term rentals (under 30 days) face enforcement under San Francisco's STR ordinance, including fines and revocation of any STR registration. Unpermitted ADU construction is subject to Department of Building Inspection enforcement actions, including stop-work orders and abatement orders. Contact SF Planning at pic@sfgov.org or the Department of Building Inspection for case-specific guidance.

San Francisco is more permissive than most cities when it comes to adu rules. That said, there are still limits.

ADU Rental Restrictions

San Francisco prohibits short-term rentals (under 30 days) of newly built ADUs unless the ADU is the host's primary residence under Admin Code Chapter 41A (Short-Term Residential Rentals). Most ADUs are restricted to long-term tenancies of 30+ days, and many fall under the Rent Ordinance once first rented.

Key details: Min Rental Term: 30 days (non-primary residence). Code Section: Admin Code Ch. 41A. STR Allowed: Only host's primary residence. Daily Fine: Up to $1,000/day. Rent Control: Pre-1979 buildings only.

Operating an unregistered short-term rental in an ADU violates Admin Code 41A.5 and carries administrative penalties of up to $1,000 per day (41A.5(d)(4)). OSTR can issue stop-rental orders, and platforms (Airbnb, VRBO) are required to remove unregistered listings. Repeat violations may result in revocation of the ADU's certificate of occupancy if used contrary to permit conditions.

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

ADU Impact Fees

San Francisco waives most development impact fees for Accessory Dwelling Units smaller than 750 square feet under Planning Code Section 401 and Cal. Gov't Code 65852.2(f)(3)(A). ADUs 750 sq ft or larger pay impact fees calculated on a proportional basis to the primary dwelling under state law.

Key details: Under 750 sf: Zero impact fees. 750+ sf: Proportional to primary unit. State Law: Gov't Code 65852.2(f)(3). SF Fee Code: Planning Code 401-411. Utility Charges: Still apply (SFPUC).

Failure to pay required impact fees blocks issuance of the building permit and the Certificate of Final Completion under Planning Code 402. Unpaid fees become a lien on the property and accrue interest at 10% per annum. Misrepresenting ADU square footage to avoid fees is a violation of Planning Code 176 and subjects the owner to enforcement penalties.

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

ADU Owner Occupancy

San Francisco does NOT require owner occupancy for ADUs, consistent with California Government Code 65852.2(a)(8) which prohibits cities from imposing an owner-occupancy requirement on ADUs permitted between January 1, 2020 and January 1, 2025, and was made permanent for most ADUs by AB 976 (2023). The owner can rent out both the primary unit and the ADU.

Key details: ADU Owner-Occupancy: Not required. JADU Owner-Occupancy: Required (state-allowed). Deed Restriction: None for ADUs. State Authority: Gov't Code 65852.2(a)(8). Rent Ordinance: Applies once rented.

There is no penalty for non-owner-occupancy of an ADU itself. However, if the owner removes a long-term tenant from the primary unit to live there and then rents the ADU separately, the change must comply with Rent Ordinance owner-move-in provisions (Admin Code 37.9(a)(8)) — non-compliance is a Rent Board violation subject to wrongful-eviction damages and three-year buyout prohibitions.

San Francisco is more permissive than most cities when it comes to adu owner occupancy. That said, there are still limits.

ADU Permits

San Francisco permits Accessory Dwelling Units ministerially in every residential and most mixed-use zones under Planning Code Section 207(c)(4) (Local ADU) and Section 207(c)(6) (State ADU). Applications are filed with the Planning Department through SF Permit Center; the state-mandated track has a 60-day review clock, and most projects do not require a discretionary hearing or neighborhood notification.

Key details: Code Section: Planning Code 207(c)(4)-(6). Review Type: Ministerial, no DR. State ADU Clock: 60-day approval. Filed With: SF Planning via PPTS. Notification: None required.

Constructing an ADU without permits results in a Notice of Violation from DBI, mandatory permit-application fees plus a 9x penalty under SF Building Code Section 110A Table 1A-K, and recordation of the NOV against title. Unpermitted units cannot be legally rented and may be ordered vacated.

The Bottom Line

Compared to many U.S. cities, San Francisco gives residents more room on accessory structures. 3 of the 6 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.