Arcadia, CA Accessory Structures: Garage Conversions (2026)

The Arcadia Development Code has no stand-alone garage conversion section. The path to living space runs through the ADU ordinance, § 9102.01.080. On a single-family lot, subsection D(1)(A) allows one converted ADU and one JADU with only a building permit when the unit sits within the existing space of an accessory structure, such as a detached garage, plus up to 150 additional square feet if the expansion is limited to accommodating ingress and egress. The unit also needs exterior access independent of the single-family dwelling and side and rear setbacks sufficient for fire and safety under the building and fire codes. A JADU can be built from an attached garage: the definition says an enclosed use within the residence, such as an attached garage, is part of and contained within the single-family structure, and the JADU is capped at 500 square feet with an efficiency kitchen and an exterior entrance.

On a multifamily lot, subsection D(1)(C) allows converted ADUs in portions of existing buildings not used as livable space, including garages, if each unit meets state building standards for dwellings, up to a quantity equal to 25 percent of the existing multifamily units, and at least one is always allowed.

Parking is where garage conversions usually get stuck in other cities, and Arcadia answers it directly. Subsection F(7)(C) states that when a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU, those off-street parking spaces are not required to be replaced. An ADU that is part of an existing primary residence or an accessory structure under the conversion scenario is also exempt from the one-space-per-ADU requirement under F(7)(B)(3).

A demolition permit for a detached garage that is to be replaced with an ADU is reviewed with the ADU application and issued at the same time. Construction of an ADU does not count as a Group R occupancy change under the local building code unless the Building Official or Code Enforcement Division makes a written finding of a specific, adverse impact on public health and safety. A garage that was never permitted as living space must still meet the local building code.