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

A garage conversion in unincorporated Plumas County is a change of occupancy requiring a building permit reviewed by the Building Department for compliance with the adopted California Building, electrical, plumbing, and energy codes (egress, light, ventilation, smoke/CO alarms). Under County Code Sec. 9-2.408(a), garages and carports may be converted to other uses only if they meet the yard requirements of the zone, except that no setback is required for an existing garage that is converted to an accessory dwelling unit; an ADU built above a garage needs only a 4-foot side and rear setback. When the conversion creates an ADU, Article 45 (Sec. 9-2.4505) and California's statewide ADU law (Gov. Code 66310-66342) apply, and the application is processed ministerially within 60 days. State law is especially permissive for conversions of existing space: a conversion ADU created within an existing structure has no front/side/rear setback requirement (Sec. 9-2.4505(e)(1)(ii)) and may expand up to 150 sq ft only to accommodate ingress and egress. When an ADU is created by converting a garage, carport, or covered parking, replacement off-street parking is not required (Sec. 9-2.4506(c)). If the garage is converted to non-dwelling space (a workshop or storage), only the building permit and applicable zoning standards apply. Confirm permit requirements with the county before starting work.