San Francisco, CA Accessory Structures: ADU Rules (2026)

For lots that have four existing Dwelling Units or fewer, or where the zoning would permit the construction of four or fewer Dwelling Units, one ADU is permitted. For lots that have more than four existing Dwelling Units or are undergoing seismic retrofitting under subsection 207.1(f) below, or where the zoning would permit the construction of more than four Dwelling Units, there is no limit on the number of ADUs permitted, as long as all other health and safety requirements are met.

(2)   The Department shall not approve an application for construction of an ADU where a tenant on the lot was evicted pursuant to Administrative Code Sections 37.9(a)(9) through (a)(12) and 37.9(a)(14) under a notice of eviction served within 10 years prior to filing the application for a building permit to construct the ADU, or where a tenant was evicted pursuant to Administrative Code Section 37.9(a)(8) under a notice of eviction served within five years prior to filing the application for a building permit to construct the ADU. This subsection (c)(2) shall not apply if the tenant was evicted under Section 37.9(a)(11) or 37.9(a)(14) and the applicant(s) either (A) have certified that the original tenant reoccupied the unit after the temporary eviction or (B) have submitted to the Department and to the Residential Rent Stabilization and Arbitration Board (Rent Board) a declaration from the property owner or the tenant certifying that the property owner notified the tenant of the tenant’s