Board backs measure allowing accessory dwelling units with seismic retrofits; members discuss short‑term rental limits

The Board of Supervisors unanimously passed on first reading March 10 an ordinance to amend the Planning Code permitting exceptions to dwelling‑unit density and other requirements when adding accessory dwelling units (ADUs) to existing buildings undergoing mandatory or voluntary seismic retrofit.

Supervisor Scott Wiener, the legislation’s author, told the board the change will incentivize the creation of modest, typically affordable housing without public subsidy and encourage property owners to complete seismic retrofits. "This legislation is a win win for San Francisco," Wiener said, noting the proposal builds on ADU legislation passed the prior year and that added units in rent‑controlled buildings would themselves be rent‑controlled.

Wiener said ADUs are usually smaller units in existing buildings where infrastructure costs are lower than with new construction, and cited UC Berkeley, HUD and AARP studies on ADU affordability. He said the Department of Building Inspection will work with property owners to smooth implementation and ensure compliance with building and safety codes.

Several supervisors voiced support; Supervisor Jane Kim said she would like future legislation to prohibit using new ADUs as short‑term rentals and to limit conversion to full‑time short‑term lodging. Supervisor Wiener responded that under legislation the board passed late the previous year, ADUs "will not be able to be permanent short‑term rentals" because every dwelling unit must have a permanent resident and comply with the short‑term rental rules.

After discussion and without objection, the board adopted the ordinance on first reading unanimously. The ordinance will return for additional readings as required by law.