Local ADU Rules
Select your location for important details
How do local ADU rules work? Cities and unincorporated San Mateo County each have their own specific ordinances that govern ADUs. These local rules must adhere to the California statewide standards. Keep in mind that if you don’t live inside the city limits of an incorporated city, then your jurisdiction is San Mateo County.
IMPORTANT: Confirm all details with local staff while planning your ADU.