Santa Rosa, CA Accessory Structures: Garage Conversions (2026)

Under Section 20-42.130, Subsection E.2.c, 'No setback shall be required for an existing legally constructed living area, garage, or other accessory structure that is converted to an accessory dwelling unit with independent exterior access from an existing or proposed residence. A setback of five feet from the side and rear property lines is required for an accessory dwelling unit constructed above an existing legally constructed garage.' Subsection E.10.h removes the parking-replacement burden: 'No replacement off-street parking spaces are required when an accessory dwelling unit is created through the conversion or demolition of a garage, carport or covered parking structure.' An ADU created entirely by the internal conversion of a detached accessory structure (such as a garage) shall not exceed 1,200 square feet (E.3.c). Internal conversions are exempt from utility connection fees and from public-improvement requirements under amended Section 18-12.015(A)(3). The application is approved ministerially within 60 days under Subsection D.2 if it complies with all development standards. Where an ADU sits above a garage, the entire combined structure cannot exceed 27 feet in height (E.4.b). Fire sprinklers are required throughout structures that exceed 1,200 sq ft total floor area, and any combination of substantial remodel/addition exceeding 50 percent of existing total floor area triggers sprinklers as well (E.3.a(1), E.3.b(1)). Garage conversions to non-habitable storage are governed by the city's Accessory Structure Policy 2.5.3 and require a standard building permit.