Simi Valley, CA Accessory Structures: Garage Conversions (2026)

Per SVMC 9-44.160(E)(1) (Ord. No. 1316), 'Detached ADUs may be new construction in yards subject to setbacks outlined in Section B or the conversion of a legally permitted accessory structures, such as a studio, shed, carport, horse stable, garage, or pool house, can be converted to an ADU. The existing space of an accessory structure within which an ADU is proposed to be located must have a solid roof and structural framing. In addition, the structure must have been permitted as required by the Simi Valley Municipal Code.' Subsection (E)(2) allows an additional 150 sq ft expansion 'to accommodate ingress and egress' so long as nonconformity is not increased. Subsection A(17) provides that 'Where an existing legally permitted accessory structure, or existing living area, is converted to an ADU or an ADU constructed in the same location, and to the same dimensions as an existing structure, no additional setbacks will be required.' For replacement parking, when an ADU is created by converting a garage, carport, or covered parking structure, no replacement parking is required (SVMC 9-44.160 Table). If an attached garage providing required SFD parking is only partially converted, the remaining space must continue to be used for parking if at least 12 ft by 20 ft (subsection A(11)). California Government Code 65852.2 preempts Simi Valley from requiring replacement parking when a garage is converted to an ADU.