Iowa City, IA Accessory Structures: Shed & Carport Rules (2026)

City Code section 14-4C-3 sets development standards for accessory structures, meant to keep them secondary to the principal building and preserve open front setback areas. A shed cannot be built before construction on the principal building has started, except for temporary construction trailers. On corner lots, detached accessory buildings must follow the intersection visibility standards of chapter 5, article D. For side and rear setbacks in residential zones, subsection B2c(1)(A) requires accessory buildings to sit at least 5 feet from a side or rear lot line that is not a street-side line; that 5-foot setback can shrink to 3 feet if the building is also set back at least 60 feet from the edge of the street pavement.

A garage or carport entered from an alley still needs a 5-foot setback from the alley right-of-way regardless of how far it sits from the street. Subsection C1 caps total lot coverage: in residential zones, the combined footprint of all detached accessory buildings cannot exceed 15 percent of the total lot area, and that percentage also counts any outdoor special vehicle storage area. No detached accessory building can sit closer than 3 feet to the principal building, and unattached accessory buildings must keep at least 3 feet between each other.

Height is capped under subsection D at 15 feet for one-story accessory buildings and structures in residential zones, and 20 feet for one-and-a-half or two-story accessory buildings. A minor modification can reduce a setback or raise the height cap through the procedures in chapter 4, article B, and a special exception before the Board of Adjustment can go further if the applicant shows the situation is peculiar to the property and practical difficulty exists, though the structure can never come closer than 3 feet to a side or rear line unless that line abuts a right-of-way or permanent open space.