Sonoma County, CA Accessory Structures: Shed & Carport Rules (2026)

Permit Sonoma's policy on Detached Residential Accessory Structures (Policy 1-4-6) governs sheds, detached storage buildings, and similar structures in the unincorporated county. A building permit is required for a detached accessory structure of 120 square feet or larger; smaller storage sheds typically do not need a building permit but must still meet zoning setbacks and may not be used for habitation. Accessory structures must comply with the development standards of the underlying zoning district, including setbacks, height, and site (lot) coverage limits. The County's zoning regulations (Chapter 26) define accessory uses to include customary residential accessory structures such as storage sheds, greenhouses, workshops, studios, garages, and carports.

Detached accessory structures generally observe minimum side and rear yard setbacks measured to the property line and a height limit for accessory structures set by the zoning district. Front-yard placement is restricted and usually must meet the primary residence's front setback. Because exact setback and height figures vary by zoning district, owners should confirm their parcel's zone and any combining districts (such as flood, scenic, or riparian overlays) with Permit Sonoma before building. Electrical or plumbing in a shed generally triggers additional permits even if the floor area is under the building-permit threshold.