Accessory Structures in Longmont, CO (2026)
5 verified accessory structures rules for Longmont, Colorado, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Longmont adopted new ADU regulations on June 3, 2025, in LMC § 15.02.080.E to comply with Colorado HB24-1152. ADUs are allowed in R-RU, R-SF, R-MN, R-MF, MU-D, and N-AG zones; an ADU is capped at 800 sq ft unless it does not exceed 50% of the principal dwelling's above-ground floor area; the owner must reside in the main house or the ADU; sale of the ADU separately from the main home is prohibited.
Longmont ADU Rules
Some RestrictionsShed Rules
Longmont does not require a building permit for a one-story shed under 120 sq ft of floor area, but anything 120 sq ft or larger requires a building permit and engineered foundation. Sheds and other detached accessory structures must sit at least 5 feet from rear and side property lines and behind the front facade of the principal building.
Longmont Shed Rules
Few RestrictionsGarage Conversions
Converting a garage into habitable space in Longmont requires a building permit from Building Inspection (Title 16) and zoning approval under the Land Development Code (Title 15). If the conversion creates a second dwelling unit, it must comply with the ADU standards in LMC § 15.02.080.E. Off-street parking requirements for the principal dwelling must still be met.
Longmont Garage Conversion
Some RestrictionsCarport Rules
Carports in Longmont are detached accessory structures regulated by the Land Development Code (Title 15) and the building code (Title 16). A building permit is required for any carport with a footprint over 120 sq ft. Carports must sit at least 5 feet from rear and side property lines and behind the front facade of the principal dwelling.
Longmont Carport Rules
Few RestrictionsTiny Homes
Tiny homes on a permanent foundation in Longmont are treated as either a single-family dwelling or an accessory dwelling unit depending on use, and must comply with the building code (LMC Title 16, adopting the IRC including Appendix Q for dwellings under 400 sq ft) and the Land Development Code (Title 15). Tiny homes on wheels (RVs) cannot be used as a primary residence in residential zones.
Longmont Tiny Home Rules
Some RestrictionsLooking for Boulder County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Longmont city rules.
Accessory Structures in Boulder County →