Antioch, CA Accessory Structures: Shed Rules (2026)

Antioch Municipal Code Section 9-5.603 ("Accessory Buildings") sets the zoning standards for detached sheds, gazebos, patio covers, and similar outbuildings in residential districts. The City defines accessory structures as buildings detached from the main building by more than five feet (sheds, gazebos, patio covers, and similar structures). In residential districts the maximum allowable height for an accessory structure is 15 feet, and detached accessory structures must be located behind the required front yard setback and cover no more than 40% of the rear yard area required for the main building. The minimum side yard for accessory structures is 20 feet on corner lots and five feet on interior lots, with a five-foot rear yard setback (10 feet on double-frontage lots). When an accessory building is attached to the main building it is treated structurally as part of the main building and must meet all primary-dwelling standards; an unattached accessory building must sit at least five feet from any dwelling on the same lot or an adjacent lot. A portable storage shed is exempt from setback requirements when placed in the rear yard, but the required front and street-side setbacks still apply on corner lots. A shed qualifies as portable - and is exempt from a building permit - when it is freestanding, moveable, and has no permanent foundation; is less than 120 square feet in area; is no more than 8 feet tall; and contains no plumbing or electrical installations. Larger or hard-wired sheds require a building permit through the Antioch Building Services Division and must comply with the currently adopted California Building Standards Code under Title 8 of the Antioch Municipal Code.