ADU Rules in San Francisco, CA (2026)
ADU rules, permit requirements, size limits, and fees for San Francisco, CA. Source-cited from official municipal code.
Yes, ADUs are allowed in San Francisco, CA.
San Francisco, CA permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. California state law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In San Francisco, the local building department handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in San Francisco.
ADU Size Limits
ADU Size Limits in San Francisco: Detached ADU: up to 1000 sq ft (max height: 18 feet). Attached ADU: 50% of primary dwelling or 850 to 1,000 square feet, whichever is greater. Junior ADU (JADU): up to 500 sq ft — must be within the existing primary dwelling or accessory structure. The Gross Floor Area of a detached ADU that provides more than one bedroom shall not exceed 1,000 square feet.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1000 sq ft · Verified May 13, 2026 · Source | 18 feet · Verified July 15, 2026 · Source |
| Attached ADU | 50% of primary dwelling or 850 to 1,000 square feet, whichever is greater · Verified May 13, 2026 · Source | 25 feet · Verified July 14, 2026 · Source |
| JADU | 500 sq ft · Verified May 13, 2026 · Source | Within existing structure |
Permit Fees
ADU Permit Fees in San Francisco: Plan check fee: Varies. Building permit fee: Varies. Impact fees: No impact fees shall be imposed on ADUs or JADUs authorized under this Section 207.2, where the ADU or JADU is smaller than 750 square feet of Gross Floor Area, or for ADUs that are proposed in lots with three existing units or fewer. Impact fees for all other ADUs shall be imposed proportionately in relation to the Gross Floor Area of the primary dwelling unit.. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | Varies — typically $800–$3,500 for standard ADU based on project valuation |
| Building Permit | Varies by valuation — typically $2,000–$6,000 |
| Impact Fees | No impact fees shall be imposed on ADUs or JADUs authorized under this Section 207.2, where the ADU or JADU is smaller than 750 square feet of Gross Floor Area, or for ADUs that are proposed in lots with three existing units or fewer. Impact fees for all other ADUs shall be imposed proportionately in relation to the Gross Floor Area of the primary dwelling unit. · Verified July 14, 2026 · Source |
| School Fees | School developer fees exempt for ADUs under 500 sqft per California Government Code §66311.5(c)(3) and Education Code §17620. ADUs 500+ sqft subject to school developer fees. |
| Total Estimate | See official source |
Permit Timeline
San Francisco ADU Permit Timeline: Permit timeline has not been confirmed — contact the department for current processing times. Apply through the local building department online permit portal. Contact them through their official website for current contact information.
Setback Requirements
ADU Setback Requirements in San Francisco: Front setback: follows zone standard. Side setback: no minimum. Rear setback: no minimum.
Parking Requirements
Parking Requirements: Parking requirements have not been confirmed — see official source.
Restrictions & Requirements
- ADU must comply with objective Planning Code standards
- ADU cannot be sold separately from primary dwelling (except under Urban Lot Split per Gov Code §66411.7)
- Short-term rental of ADU requires primary resident to be on-site during rental
- ADU must have permanent foundation
- In-law units in RH-1 zones must meet residential habitability standards
- Hillside areas may have additional structural review requirements
How Many ADUs Are Allowed?
Number of ADUs Allowed in San Francisco: Single-family lots: not confirmed — see official source. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- 1 ADU + 1 JADU per single-family lot (RH-1, RH-2 zones)
- Multifamily Properties
- Up to 25% of existing units (minimum 2) as detached ADUs; 1 ADU per existing unit for internal conversions per Gov Code §66323(a)(3)
Statewide Preemption
ADU Preemption
California state law preempts local ADU rules — local governments cannot impose stricter standards.
View California preemption detailsState Law & Preemption
State Preemption: CA state law preempts local ADU restrictions. San Francisco must approve compliant ADU applications by right.
Frequently Asked Questions
Can I build an ADU in San Francisco?
Yes. San Francisco, CA allows accessory dwelling units. On a single-family lot you can build 1 ADU + 1 JADU per single-family lot (RH-1, RH-2 zones).
How big can an ADU be in San Francisco?
The maximum size for a detached ADU in San Francisco is 1,000 square feet. A Junior ADU (JADU) can be up to 500 square feet.
How long does it take to get an ADU permit in San Francisco?
The typical ADU permit timeline in San Francisco is The permitting agency shall either approve or deny the application to create or serve an accessory dwelling unit within 60 days from the date the permitting agency receives a completed application if there is an existing single-family or multifamily dwelling on the lot. Note: SF DBI typically processes ADU permits in 2-6 weeks for plan check; SF Planning pre-approval may add time if design review is triggered (operational, not codified).. Total estimated permit fees are $3,000–$10,000 total permit fees depending on size and scope.
Do I need extra parking for an ADU in San Francisco?
San Francisco parking rules for ADUs: No additional parking required for ADUs within one-half mile of public transit (BART, Muni Metro, major bus lines). SF is characteristically transit-rich — parking waivers are available throughout much of the city per California Gov Code §66322(a)(1) and SF Planning Code Section 207.1. Note: the 'entirely transit-rich' characterization is an editorial interpretation; the statutory mandate applies wherever a unit is within one-half mile of public transit per §66322(a)(1).
Do I have to live on-site to have an ADU in San Francisco?
Owner-occupancy requirement in San Francisco: No additional standards, other than those provided in Section 66314, shall be used or imposed, including an owner-occupant requirement, except that a local agency may require that the property may be used for rentals of terms 30 days or longer.
Source: San Francisco Planning Code Section 207.1; California Government Code Chapter 13 §§66314–66333 (Stats. 2024 Ch. 7 §20). Last verified April 5, 2026. View source