Alameda, CA Accessory Structures: Garage Conversions (2026)

Under AMC Section 30-5.18, when a garage, carport, or covered parking structure is demolished or converted in conjunction with construction of an accessory dwelling unit, replacement of the parking space(s) is not required - a key Alameda allowance that follows state ADU law. The existing driveway and curb cut may remain for off-street parking if the driveway is at least 18 feet long (measured from the property line) so a vehicle parks without encroaching into the right-of-way; driveways shorter than 18 feet must be abandoned per Section 22-18.3 as part of the ADU work. Per the City's ADU FAQ, an ADU built within an existing garage may include an expansion of no more than 150 sq ft beyond the same physical dimensions as the existing garage; a second story is allowed only if the existing garage framework can accommodate it, with the second-story ceiling not exceeding 16 feet. Historic note: if the garage being converted or demolished was constructed before 1942, a Certificate of Approval application (a discretionary review with neighbor notification) must be approved by the Planning Division to determine whether the garage is a historic resource before the ADU building permit can be issued. The conversion is otherwise reviewed ministerially.