San Francisco ADU Basics
California grants residential property owners broad leeway to construct Accessory Dwelling Units on their properties. These ADUs can be an easy way to produce new rental units and are subject to a variety of protections that require cities to allow them to be built. San Francisco has particular rules governing the construction of these units.
Your individual situation may be different. We recommend speaking to an experienced architect and/or lawyer before proceeding with any construction or modification of your property.
How many new units can you build?
Single Family Homes: Property owners have the right to build an ADU of at least 800 sq ft with a 16 ft height limit and four-foot side and rear yard setbacks. Property owners may additionally construct a JADU (Junior Accessory Dwelling Unit) within the existing building envelope or an accessory structure.
Multi-family Buildings: Property owners have the right, under state law, to build one ADU or a number of ADUs equal to 25% of the building’s existing units, whichever is larger. San Francisco allows unlimited ADUs in multi-family buildings with more than five units, provided there is space to accommodate them.
What is the process for getting an ADU approved by the City?
In San Francisco there are two main types of ADUs: those that fulfill all of the cities requirements and those that do not fulfill certain requirements and therefore require one or more waivers. In either case the approval process must be ministerial, meaning that it must be entirely administrative. No hearings, neighborhood notification, or discretionary review is permitted.
Non-Waiver Program ADUs: If your property meets all of the requirements under city law (open space, exposure, etc.) you must be granted “by right” approval. This means that as long as your unit(s) are code compliant they must be approved.
Waiver Program ADUs: If you would like to construct a JADU in addition to your ADU and it does not fulfill certain requirements or if you are building more than one ADU in a multifamily building you may need to apply for waivers from the Zoning Administrator. Depending on which waivers you apply for you may need to sign a regulatory agreement voluntarily submitting the new unit to rent control.
What common issues do property owners encounter when trying to get their units permitted?
Fire Safety - The city requires sprinklers in multi-family buildings and ADUs, this can be expensive and in some rare cases impossible due to insufficient water main pressure. The city also requires rescue openings (windows or doors) for bedrooms. This can make it difficult to build bedrooms that do not face a backyard or street and may necessitate the construction of an additional access path to the street.
Exposure - All new units in San Francisco are required to have access to a certain amount of natural light. This may not be a problem as many ADUs are built facing the street or a rear or side yard. You may also seek a waiver to this requirement.
Open Space - ADUs in San Francisco are subject to open space requirements. This is no longer enforceable as state law specifically prohibits any law that limits the size of an ADU below the minimum threshold. If you are building more than one ADU you may still be subject to open space requirements, though you can seek a waiver for this standard as well if necessary.
Evictions - If any kind of “no fault” eviction has taken place in your building in the last ten years or an “owner move in” eviction has taken place in the last five years, you may not apply for any waivers to ADU standards.
If you have any questions please contact us at hello@yimbylaw.org.