Longmont, CO Accessory Structures: Shed Rules (2026)

Longmont Building Inspection follows the International Residential Code as adopted in LMC Title 16. Under that code, a one-story detached accessory structure used as a tool or storage shed, playhouse, or similar use is exempt from building permit requirements when the floor area does not exceed 120 square feet. Wind tie-downs or anchorage are still recommended for permit-exempt sheds. Once the structure is 120 sq ft or larger, a building permit is required and foundations must be designed by an engineer based on the soil under the structure. Required structural elements for engineered sheds include 1/2-inch anchor bolts embedded at least 7 inches and spaced no more than 4 feet apart, 2x4 minimum studs at 24 inches on-center, double top plates, and lateral bracing. Setbacks: under LMC § 15.03.080.C (with accessory structure exceptions), all detached accessory structures must be located at least 5 feet from rear and side property lines and behind the front facade of the principal building. Total combined floor area of all accessory structures on a residential lot may not exceed 75% of the principal structure's floor area. Sheds may not be used as habitable space and may not contain plumbing fixtures unless separately permitted.