Longmont, CO Accessory Structures: Shed & Carport Rules (2026)

Section 16.06.060 amends Section R105.2 of the 2024 International Residential Code, the code's list of work exempt from a building permit, as adopted through Ordinance No. O-2026-24, effective June 9, 2026, which repealed and replaced the entire chapter 16.06. The city rewrote subsection 1 of that list to cover only one-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided the floor area is 200 square feet (18.58 square meters) or less, and it deleted subsections 2 and 10 of the model list outright rather than adopting them locally.

A shed under the 200-square-foot line needs no building permit, no plan review and no inspection for the structure itself. Cross that line and the shed becomes a permitted structure: the owner applies for a building permit, pays a fee set by city council resolution under Section 16.06.090, and gets the construction documents reviewed and stamped under Section 16.06.080. That permit lapses if no inspection occurs within 365 days of issuance, or within 180 days of the prior inspection, under Section 16.06.070, and the building official can grant extensions of up to 180 days for written, justified cause.

Falling under the permit-exemption threshold does not exempt a shed from Longmont's zoning code. Section 15.04.040 of the Land Development Code requires any accessory structure over 120 square feet to sit at least five feet from the property line, while a smaller structure needs only three feet of separation but cannot cover more than half of the combined required rear and side setback area, and must be sited to accommodate lot drainage. Section 16.06.140 separately defines a detached structure as an accessory building set at least five feet from the principal structure.

Residential accessory structures, permit-exempt or not, also cannot exceed 50 percent of the principal structure's floor area (75 percent combined) and cannot stand taller than the house itself.