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 Big West Coast ADU Dataset.
These are the cities with the most permitted ADUs since California's 2017 zoning reforms.
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. Source: BuildinganADU.com Big West Coast Dataset.
CSLB-verified ADU specialists in your area. License number, classification, and date issued visible.
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.