County · California
ADU rules in Alameda County
These are the primary sources for accessory dwelling unit regulations in Alameda County: the county's own zoning code, planning department pages, and permit guides. Start here before talking to anyone: the rules below are what your permit reviewer will apply.
Unincorporated areas only
County zoning applies only outside city limits. If your property is inside a city or town, that municipality's own ADU ordinance governs instead, even though it sits within Alameda County.
Find your city's rules in CaliforniaADU regulations
California statewide law also applies
California sets baseline ADU rights at the state level. Where local rules are stricter than state law allows, state law usually wins, so both are worth reading.
See California statewide rulesSpotted something outdated?
Zoning codes change. If a link is dead or Alameda County has updated its ordinance, report it and we'll verify against the official source.
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