Independent guides to the cost of building an accessory dwelling unit in 563 California cities and counties. Sourced from CSLB, UC Berkeley ADU research, and the California HCD Annual Progress Reports (April 2026 refresh).
Directory
These are the cities with the most permitted ADUs since California's 2017 zoning reforms.
For journalists & researchers
The headline data, sourced and dated. 180,329 permits issued 2013–2024, Berkeley ordinance grades for 424 jurisdictions, 2026 cost regression across seven regions, and CSLB-verified contractor counts — all on one citable page. Suggested citation provided.
What's inside
Per-square-foot pricing by ADU type, regionalised for the Bay Area, LA, San Diego, Sacramento and Central Valley.
State-law minimums plus links to your city's actual ordinance text. What's allowed, what isn't, what changed.
How many ADUs your city has actually permitted, year by year. Sourced directly from California HCD Annual Progress Reports (April 2026 refresh). Raw data →
CSLB-verified ADU specialists in your area. License number, classification, and date issued visible.
About
Most "ADU cost in [city]" results are written by builders pitching themselves. We're not a builder. We don't take referral fees from contractors we feature. BackyardADU compiles public data — CSLB, the California ADU Scorecard, the Big West Coast ADU Dataset, and city ordinance text — so homeowners can decide with eyes open.
