Sierra County, CA Accessory Structures: Garage Conversions (2026)

Sierra County does not have a standalone garage-conversion ordinance; conversions are handled through the ADU regulations in SCC 15.10.030 (Ord. 1133, eff. 1/2/25) and the building permit process. The code expressly allows an ADU within an existing or proposed primary dwelling (including attached garages), within an existing or proposed detached accessory structure, or above an attached or detached garage. For setbacks, no setback is required for an existing detached private garage that is converted to an ADU, except as required for fire and safety; an ADU built above an existing garage requires four-foot interior side, street side and rear setbacks. A converted garage ADU located within the existing structure does not require rear, side or street-side setbacks. The county also provides that if a garage, carport, or covered parking is demolished or converted in conjunction with creating an ADU, replacement parking is not required - a key benefit for owners of rural Sierra parcels. Any conversion still requires a ministerial building permit (acted on within 60 days), must provide separate exterior access, and must meet California Building Code health, safety and wildfire standards. Permitted garages remain an allowed accessory use in residential zones such as RR-1 (SCC 15.12.190), so a garage may also simply be re-used for storage or workshop space, subject to building code if habitable space or utilities are added.