San Francisco’s ADU Ordinance

Accessory dwelling units (ADUs) have the potential to provide a rare and valuable source of rental housing in San Francisco’s single-family neighborhoods. The current San Francisco rules, however, make it very difficult for homeowners to add ADUs on single-family properties. Requirements for yard setbacks and open space severely limit the lot area where an ADU can go, and the arduous permit review process discourages homeowners from even attempting to add an ADU. In reviewing the San Francisco ordinance, CaRLA identified two of these limits on ADUs that are in conflict with state law.

First, the ordinance subjects ADUs to the city’s discretionary review process which allows virtually anyone to indefinitely delay an ADU application through countless Planning Commission hearings, even though the proposal may be 100% compliant with local zoning. This process is very costly for permit applicants and can take months to navigate. The mere possibility of such burdens is more than enough to discourage most homeowners looking to add an ADU.

Second, the San Francisco ordinance only allows ADUs to be added to existing homes; new single-family homes are prohibited from including one. The city’s single-family neighborhoods are primarily composed of small lots where it is much easier to include an accessory unit when it is incorporated into the design of the primary home from the start. By prohibiting ADUs from applications for new homes, San Francisco is needlessly limiting units being developed in high cost, high opportunity single-family zones, where the need for this form of affordable-by-design housing is highest.

CaRLA filed a lawsuit to correct these issues. These changes will make it easier for homeowners to add ADUs to single-family homes, and provide renters more affordable access to San Francisco’s high-cost, high-opportunity neighborhoods.

How it Ended

Sometimes the Bay Area’s biggest quaint village takes over 15 years and a lawsuit to comply with a very simple demand of state law. Since 2002, state law has mandated that local governments process accessory dwelling unit permits through a quick, nondiscretionary permitting process that does not allow for appeals. San Francisco had simply ignored this simple mandate for nearly two decades before CaRLA was forced to file a lawsuit. 

In response to the real legal threat, San Francisco enacted a citywide ordinance to exempt all ADUs from discretionary review and allow for ADUs in new developments. CaRLA agreed to settle the lawsuit once this ordinance was finally enacted, opening up San Francisco to ADU development and effectively ending single-family zoning in the city.