City ADU planning guide

San Francisco ADU regulations and next steps

Start with the most important planning decisions, then review the detailed city rules below before choosing a detached ADU plan or requesting a property-specific feasibility review.

San Francisco ADU rules overview

Detailed local requirements vary by property. Use this section as a starting point for setbacks, parking, height, utilities, and approval considerations.

Lot fit

Setbacks and buildable area

Start with rear and side setbacks, lot coverage, access, and where a detached ADU can realistically sit on the property.

Design limits

Size, height, and unit type

Check whether the property is better suited for a detached ADU, attached ADU, garage conversion, or junior ADU.

Approvals

Parking, utilities, and permits

Confirm parking exemptions, utility connection requirements, impact fees, and city review steps before finalizing plans.

Accessory Dwelling Units (ADUs) in San Francisco are regulated by both the city's local ordinances and California state laws. These regulations have been evolving over the years to encourage more housing options while balancing neighborhood character and urban planning considerations.

Key ADU Regulations in San Francisco (as of 2024)

Types of ADUs:

  • Class 1 ADU (Interior Unit) Converted within existing space, such as a basement, attic, or garage. No new construction is required.
  • Class 2 ADU (New Construction or Expansion) Involves new construction or an expansion to an existing structure (e.g., adding a unit above a garage or converting a portion of the house).
  • Junior ADU (JADU) A smaller unit, typically no larger than 500 square feet, that is created by converting an existing room in a single-family home.

Zoning and Location Requirements:

  • Residential Zones ADUs are permitted in most residential zoning districts, including RH (Residential House), RM (Residential Mixed), and NC (Neighborhood Commercial) districts. However, there may be restrictions based on the specific zone.
  • Minimum Lot Size Generally, there is no minimum lot size for building an ADU, but the unit must meet all other development standards, such as setbacks and open space requirements.

Size and Height Limits:

  • Class 1 ADUs Up to 1,200 square feet in size, but the exact size may vary based on the existing building and zoning district.
  • Class 2 ADUs (New Construction) The maximum size is typically 1,000 square feet for a detached unit, though it can vary depending on the site and existing structure.
  • Junior ADUs Must be a minimum of 150 square feet but can be no larger than 500 square feet.
  • Height Limitations ADU height is typically capped at 16 feet for detached units, but this can vary depending on the zoning and neighborhood.

Parking Requirements:

  • Parking Exemptions In many cases, no additional parking is required for an ADU, especially if the property is located within a certain distance of transit or in areas with a high walkability score. Parking may be required for units that are not located in transit-rich areas.
  • Replacement of Parking If a garage is converted into an ADU, the parking space is generally not required to be replaced, though this can vary depending on specific zoning regulations.

Setbacks and Lot Coverage:

  • Setback Requirements Generally, the front, side, and rear setbacks for ADUs must comply with the base zoning district’s requirements, but certain adjustments can be made. For example, ADUs constructed in areas that are considered "transit-rich" or close to major transit corridors may have more lenient setback rules.
  • Lot Coverage ADUs must comply with the lot coverage requirements for the specific zoning district, which dictates how much of the property can be covered by buildings.

Design and Aesthetic Requirements:

  • Consistency with the Primary Structure ADUs must match the design and materials of the main house to ensure architectural harmony with the surrounding neighborhood.
  • Privacy and Light In some cases, ADUs must be designed in a way that preserves privacy for neighboring properties, such as limiting the size of windows facing into private yards or requiring additional screening.

Permitting Process:

  • Ministerial Approval In most cases, ADUs are subject to a streamlined review process under the state’s "ministerial " approval system, meaning they are approved as long as they comply with zoning and building codes.
  • Planning Department Review The San Francisco Planning Department typically reviews ADU projects to ensure they comply with local design and zoning standards. However, many ADUs can be approved without a discretionary review (e.g., conditional use permit), depending on the specifics of the project.

Incentives and Financing:

  • Expedited Review Some ADUs may qualify for expedited permitting, especially if they meet specific sustainability criteria or are part of affordable housing programs.
  • Incentives The city may offer incentives for building ADUs, such as reduced fees, or funding opportunities for low- or moderate-income homeowners.
  • Affordable Housing Requirements In some cases, particularly with larger developments, affordable housing requirements may apply to new ADUs.

State Laws Impacting ADUs in San Francisco:

  • SB 9 (2021) Allows for the creation of two units on a single-family lot, potentially creating more opportunities for adding ADUs in conjunction with the primary residence.
  • SB 13 (2019) and AB 68 (2019) These state laws have reduced the regulatory barriers for ADUs, such as eliminating certain fees for ADU construction and streamlining the approval process. They also increased the allowed size of ADUs and limited certain local restrictions, especially for smaller units.

Fees and Costs:

  • Impact Fees For larger ADUs, impact fees may apply, typically for projects over 750 square feet. These fees help fund infrastructure improvements but can vary depending on the unit’s size and the neighborhood.
  • Permit Fees Permit fees for ADU projects vary based on the scope of work. These can include fees for building permits, zoning reviews, and inspections.
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