CA SB831

Requires local agencies to allow accessory dwelling units (ADUs) in single-family and multifamily residential zones and designate areas where ADUs may be excluded only for documented health and safety purposes.

Establishes that ADU square footage cannot be counted toward floor-to-area ratio or lot coverage limits, and prohibits minimum lot size requirements for ADUs unless specific health and safety findings are made.

Mandates ministerial approval of ADU permit applications within 60 days, with automatic approval if the local agency fails to act; prohibits requiring owner occupancy and voids any agreements requiring it.

Eliminates requirements to replace off-street parking when garages or carports are demolished or converted for ADU construction, and prohibits using other local ordinances to delay ADU building permits.

Allows building officials to delay enforcement of non-critical building code requirements for substandard ADUs for at least 10 years upon owner request (through January 1, 2029).