California state law preempts most local ADU restrictions. These are the universal rules every California city must allow. Your city may be more permissive on some — never more restrictive.
| Rule | Standard |
|---|---|
| ADUs allowed on single-family lot | Yes — required by state law |
| Max units per lot | 1 ADU + 1 JADU on single-family; up to 2 detached ADUs + JADU on multifamily |
| Owner-occupancy required | Cities can't require for ADUs (state preempts) |
| Min side & rear setback (detached) | 4 feet |
| Max height (detached, single-family lot) | 16 ft — 18 ft if within 0.5 mi of major transit |
| Off-street parking replacement | None required if within 0.5 mi of public transit; same applies to garage conversions |
| Max ADU size (detached) | 850 sqft for studio/1BR; 1,000 sqft for 2+BR (city may allow more) |
| Min lot size | No minimum required by state |
| Permit timeline (ministerial) | 60 days from complete application (state law) |
| Fire sprinklers required in ADU | Only if main house has them (state preempts) |
| Impact fees | Waived for ADUs under 750 sqft |
State law sets a floor, not a ceiling. Cities retain authority over:
Each California city's planning department publishes its ADU ordinance. Our city pages link to the actual ordinance text where available (157 cities have direct links from the UC Berkeley ADU Scorecard).
Browse 279 California cities →