ADUs in San Francisco: Rules & How to Build

San Francisco has become one of the easier big cities in California to add an accessory dwelling unit. Recent state and local changes stripped out much of the old red tape — but there are still city-specific rules worth knowing before you build. Here’s a plain-English look at the ADU rules in San Francisco. (For the statewide baseline, see our Bay Area ADU guide.)

Two ADU programs

San Francisco runs a Local ADU Program and the State-Mandated ADU Program, and you pick whichever fits your project best. The local program can allow more units in some buildings; the state program offers guaranteed sizes and streamlined approval. A good ADU designer will help you choose.

Key San Francisco rules

  • Ministerial, no neighbor notice: ADU permits are handled administratively. The old Section 311 neighborhood-notification process no longer applies — a major source of delay is gone.
  • 60-day approval on a complete application, with pre-approved plan options available.
  • Multi-family buildings: State rules allow up to eight detached ADUs on an existing multi-family property, with no replacement parking required.
  • Legalizing unpermitted units (AB 2533): It’s now easier to bring an existing unpermitted ADU into compliance — for units built before Jan 1, 2020, permits generally can’t be denied over non-safety issues.
  • Minimum standards: ADUs must be at least 220 sq ft with 7.5 ft ceilings; state-program ADUs run up to 850 sq ft (studio/1BR) and 1,000 sq ft (2BR+).
  • Parking: No replacement or added parking is required for most ADUs, especially within a half-mile of transit — which covers much of the city.

This page is general information, not legal or construction advice, and rules change. Confirm specifics with SF Planning before you build. We’re always happy to refer trusted ADU architects and contractors who know the city’s process — just ask.

Thinking about an ADU in San Francisco?

We’ll help you weigh the cost, the rules for your block, and what it means for your home’s value. Start with a free home valuation or call (415) 407-5324. See also: ADUs in Marin, San Mateo County, and the East Bay. — Beatrice Kopilenko, REALTOR® · DRE #01970797 · Primavera Realty