Historic Preservation Commission approves ordinance aligning ADU rules with state law, clarifies preservation limits

The San Francisco Historic Preservation Commission on Sept. 1 approved a Planning Department recommendation to amend local code so it aligns with recent state mandates for accessory dwelling units (ADUs), voting unanimously to adopt the ordinance with a staff modification.

Veronica Flores, Planning Department staff, told the commission the ordinance clarifies ministerial review for state-mandated ADUs and junior ADUs, adopts an explicit 16-foot height limit where required by state law, reduces the maximum permissible size for some detached ADUs, and clarifies how height is measured for rear-yard detached ADUs. Flores said the ordinance incorporates changes required by state law and retains objective architectural review standards recommended previously by the commission.

Deputy City Attorney Peter Mlynich explained the legal limits on local authority. He said California law generally prevents jurisdictions from imposing rent-control conditions on units approved under the state-mandated ADU programs because the city lacks discretion to deny or condition those projects; the Costa Hawkins Rental Housing Act permits local rent controls only when a city can bargain with a property owner under a binding contract. "The city doesn't have the discretion to deny or modify those projects," Mlynich said, describing why that limits the city's ability to require rent restrictions on state-mandated ADUs.

Planning staff also described a recommended modification, which the commission included in its motion: allow up to two detached ADUs under the local program within the required rear yard (matching the state-mandated allowance), subject to 16-foot maximum height and 4-foot side and rear setbacks. Flores said this local modification aims to yield more rent-controlled units under the city's discretionary program while keeping the city code consistent with state requirements.

Commissioners asked about preservation and neighborhood guidelines. Natalia Kwiatkowski, planning staff and preservation planner, said state-mandated ADUs are processed ministerially and are not subject to CEQA or discretionary neighborhood design review, limiting the commission's direct review authority. However, she said the city may impose ministerial, objective standards to prevent "adverse impacts" on properties listed in the California Register of Historic Places and that preservation review in those cases would generally occur at the staff (administrative) level using Secretary of the Interior standards.

After discussion, a motion to adopt staff's recommendation, including the staff modification described by Flores, was moved and seconded. The commission voted unanimously (7–0) to approve the ordinance and include the staff modification. Deputy City Attorney Mlynich requested confirmation that the modification was included in the motion; staff confirmed the modification was intended and the commission members indicated assent.

The matter passed before the Historic Preservation Commission; the transcript records no public speakers on the item and the commission did not record any amendments beyond the stated staff modification.