Data report · 2026
State of California ADU Rules 2026
California's ADU law sets a statewide floor, but what you can actually build is decided city by city. Across the 487 California cities in GoCodebook's ADU dataset,405 apply at least one local rule that goes beyond the state baseline, and 450 carry ordinance-cited local data. Every number on this page is computed directly from the dataset behind ourcity-by-city comparison.
Where cities diverge from state law
Most generous detached-ADU size allowances
The state floor guarantees a detached ADU of 1,200 sq ft; these cities allow more by local ordinance.
| City | Detached ADU max size |
|---|---|
| Hidden Hills | 1,500 sq ft |
| Menifee | 1,500 sq ft |
| Woodside | 1,500 sq ft |
| Beverly Hills | 1,400 sq ft |
| Fresno | 1,400 sq ft |
| Alameda | 1,200 sq ft |
| Alhambra | 1,200 sq ft |
| American Canyon | 1,200 sq ft |
About this data
The dataset pairs the California state-law baseline with each city's local ADU ordinance where one has been compiled and cited (see our methodology). Cities without ordinance-cited local data resolve to the state floor and are excluded from local-rule counts. Explore the full table on ADU rules by city, read California ADU law explained, or open any city's page for its rules with citations.
Journalists and researchers: you're welcome to cite these figures with attribution to GoCodebook (link to this page). Figures are AI-compiled from adopted ordinances and cited to the ordinance text — spot-check the cited section before publication. Figures regenerate as the underlying ordinance data is updated — this page always reflects the current dataset.
Check the rules for your exact parcel
Aggregate stats can't see your lot. Ask GoCodebook about your address for the ADU size, setbacks, parking and permit path that actually apply — with citations.
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