Westminster, CA Accessory Structures: Garage Conversions (2026)

Westminster's ADU regulations (Municipal Code Section 17.400.135, adopted as Ordinance No. 2572) expressly recognize converting an existing garage or other accessory structure into an accessory dwelling unit. The city's official ADU page lists, as one of four ways to establish an ADU, the "conversion of an existing garage or other accessory structure on a lot containing an existing single-family dwelling, provided it is set back at a distance sufficient for fire safety." Garage-conversion ADUs are reviewed ministerially through the combined Planning Division Zoning Clearance and Building Division plan check. Under California ADU law that the city implements (Gov. Code 65852.2), conversion of existing garage space to an ADU generally does not trigger a requirement to replace the displaced parking. Note that the garage's prior off-street parking interacts with the city's parking rules: Westminster's Off-Street Parking chapter (Chapter 17.320) and R1 standards require covered parking, but state ADU law limits the city's ability to demand replacement parking for a conversion ADU. Converting a garage into living space that is NOT a permitted ADU—e.g., an unpermitted bedroom or rental room—violates the building and zoning codes; living in an accessory structure is prohibited. These are city standards, distinct from any Orange County rules.