Before You Build in Longmont, CO: Permit & Rule Checklist (2026)

Longmont requires a building permit for every fence project, including new fences, replacement of any amount of existing fence, swapping fence types (e.g., chain link to wood privacy), changing the location of a fence, and replacing deteriorated fencing with the same material at the same height. Permits are issued by Building Services at 385 Kimbark Street.

All swimming pools deeper than 24 inches and all hot tubs and spas must be enclosed by a fence at least 4 feet tall with openings no larger than 4 inches, per the Building Services 'Fences' guide implementing LMC 15.05.100 and the adopted 2021 International Codes. Gates must have a latch meeting the adopted code, or, for hot tubs/spas, a lockable safety cover meeting the 150-pound load standard may substitute.

Under Longmont Land Development Code (LMC) Chapter 15.05.100, residential fences and walls may be a maximum of 6 feet tall, and non-residential fences/walls a maximum of 8 feet. Fences in the front yard (between the front lot line and the front facade) are limited to 42 inches and must be at least 50% transparent. Stricter limits apply within sight distance triangles at corners and driveways.

Longmont Municipal Code requires the finished (smooth) side of any fence to face the public right-of-way, common open space, or other public areas. Property owners — not the City — are responsible for locating property lines. The City does not adjudicate private 'good neighbor' or boundary-line disputes; those are civil matters under Colorado law.

Longmont allows wood, vinyl, masonry, and ornamental metal fencing under LMC 15.05.100. Any species of wood may be used above ground; wood in contact with concrete or soil must be pressure-treated or naturally rot-resistant (redwood or cedar are explicitly suggested). Chain-link is allowed in side and rear yards of residential lots and throughout non-residential properties, but not in residential front yards.

Longmont does not publish a stand-alone retaining-wall guide; walls are regulated under the adopted 2021 International Building Code (IBC) and 2021 International Residential Code (IRC), enforced by Building Services. Under IRC R404.4 and IBC standards, a permit is generally required when a retaining wall exceeds 4 feet measured from the bottom of the footing to the top of the wall, or when the wall supports a surcharge (slope, driveway, structure).

Longmont requires a building permit for any swimming pool (in-ground or above-ground over 24 inches deep), spa, or hot tub. Permits are issued by Building Services at 385 Kimbark Street under the city's adopted 2021 International Codes (effective January 1, 2022). Pool barriers, electrical bonding, and gas/plumbing all require inspection.

Beyond the 4-foot barrier rule in LMC 15.05.100, Longmont enforces the 2021 IRC Appendix V and 2021 IBC pool-safety provisions: anti-entrapment drain covers compliant with the federal Virginia Graeme Baker Pool & Spa Safety Act, equipotential electrical bonding around the pool shell, alarms on dwelling doors that open directly to the pool area, and required final inspection before filling the pool.

Longmont requires every pool deeper than 24 inches and every hot tub or spa to be enclosed by a barrier at least 4 feet (48 inches) tall, with no opening larger than 4 inches, per LMC 15.05.100 and the adopted 2021 IRC Appendix V. Gates must self-close and self-latch, opening outward away from the pool, with the latch release at least 54 inches high.

Hot tubs and spas require a building permit in Longmont and must be enclosed by a 4-foot fence with openings under 4 inches per LMC 15.05.100 - OR they may use a lockable safety cover capable of supporting at least 150 pounds, which must be locked when the spa or hot tub is not in use. Electrical work must comply with the adopted 2020 NEC Article 680 (GFCI protection and bonding).

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.

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 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.

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.

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 allows recreational fires with a fuel area of three feet or less in diameter and two feet or less in height, burning only natural untreated wood, kept 25 feet from any structure or combustibles, and attended until fully extinguished. The rules are administered by Longmont Fire Services under the 2021 International Fire Code adopted by Ordinance O-2021-66 (LMC Chapter 16.32). Burning is prohibited on Red Flag days.

Open burning is prohibited within Longmont city limits unless specifically allowed by the burning regulations or permitted by the Longmont Fire Department. No burning of leaves, trash, yard debris, or household waste is allowed as a means of disposal. No burning of any kind is allowed on Red Flag warning days. The rule is enforced by Longmont Fire Services under the 2021 International Fire Code (LMC Chapter 16.32, Ord. O-2021-66).

Removal of a healthy, high-value tree on City property or in the public ROW requires a Forestry Services permit and triggers appraisal and mitigation under LMC 13.24.110. The City Forester sets the appraised value, and equivalent replacement value must be paid or planted. Stump grinding is required with every approved removal.

Pruning of city-owned trees and trees in the public right-of-way requires a permit from Longmont Forestry Services and must be performed by a City of Longmont Licensed Tree Contractor under LMC Chapter 6.88. Work must follow ANSI A300 standards and ISA Best Management Practices.

As of 2026 Longmont is at a Mild Drought Response Level (Drought Watch) with no mandatory restrictions and no assigned watering days. The City recommends no more than two watering days per week and no irrigation before May 1. An updated 'waste of water' ordinance under LMC Chapter 14.04 took effect in May 2026.