Longmont's Fence Regulations: The Rules That Matter

Every city handles fence regulations a little differently. In Longmont, Colorado, there are 8 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

Permit Requirements

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.

Key details: Permit Required For: All new fences, replacement of any amount, material change, location change. Permit Exempt: Non-structural, non-property-line privacy screens (not staked into ground). Application Documents: Permit form + ILC/plot plan with setbacks. Where to Apply: Development Services Center, 385 Kimbark St., or Citizen Access online portal. Inspection Required: Yes; final inspection (owner need not be present).

Building a fence without a permit can result in a stop-work order, required removal or relocation, re-inspection fees, and potential insurance liability. Code enforcement may issue municipal citations.

This is not one of those rules that cities tend to ignore. Longmont actively enforces its permit requirements requirements.

Pool Barriers

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.

Key details: Trigger Depth: Pools deeper than 24 inches; all hot tubs/spas. Minimum Fence Height: 4 feet (LMC) / 48 inches (2021 IRC App. V). Max Opening: Less than 4 inches. Gate: Latch per adopted code; self-closing/self-latching opening outward (2021 IRC). Latch Release Height: At least 54 inches from bottom of gate.

A pool or spa cannot be filled and used (and will fail final inspection) until a compliant barrier is installed. Removing or disabling a barrier or gate latch is a code violation and creates serious child-drowning liability. Building Services can require correction, charge re-inspection fees, and refer the matter to code enforcement.

This is one of the stricter rules in Longmont's municipal code. If you are unsure whether your situation complies, it is worth checking with the city before proceeding.

Height Limits

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.

Key details: Residential Max Height: 6 feet (LMC 15.05.100). Non-Residential Max Height: 8 feet. Front Yard Max Height: 42 inches, at least 50% transparent. Sight Triangle (Street/Alley): 30 ft along each curb; max 36 in solid or 42 in if 50% open. Sight Triangle (Driveway): 15 ft along each side; same height rule.

Fences exceeding code height, blocking sight distance, or installed in the front yard in violation of the 42-inch / 50%-transparent rule must be lowered, relocated, or replaced. Building Services and Code Enforcement can require correction, charge re-inspection fees, and pursue municipal code enforcement.

Neighbor Fence Rules

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.

Key details: Finished-Side Rule: Smooth side must face public ROW/common area (LMC 15.05.100). Property Line Surveys: Owner's responsibility - city does not survey. HOA Rules: Owner must comply with any applicable HOA standards. Cost-Sharing Statute: No local cost-sharing ordinance; civil matter under Colorado law. Construction Noise: LMC 10.20.100 prohibits unreasonable noise.

A fence with the finished side facing the wrong way may be cited. Fences encroaching on a neighbor's property must be removed or relocated at the offending owner's expense; the City does not survey or adjudicate.

Approved Materials

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.

Key details: Wood: Any species above grade; pressure-treated/rot-resistant when in contact with soil/concrete. Suggested Wood: Redwood, cedar, pressure-treated lumber. Vinyl / Composite: Allowed. Masonry / Brick / Stone: Allowed (subject to height and sight-triangle rules). Ornamental Metal: Allowed.

Using non-treated wood at grade can cause early rot and require replacement. Installing chain-link in a residential front yard, or any prohibited material (barbed wire, tin/sheet metal, electric except invisible pet fence), is a code violation requiring removal.

Retaining Walls

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).

Key details: Adopted Code: 2021 IBC and 2021 IRC (effective Jan. 1, 2022). Permit Threshold: Greater than 4 ft (footing to top), per IRC R404.4. Surcharge Walls: Permit required at any height if surcharge or structural load. Sight Triangle Limit: 36 in solid / 42 in if 50% open (LMC 15.05.100). Engineering Required: Walls greater than 4 ft or surcharge walls need stamped design.

Building a retaining wall over 4 feet, or any height with a surcharge, without a permit and engineered drawings can result in stop-work orders, required removal or re-engineering, and re-inspection fees. Walls within the sight triangle that exceed 36 inches solid must be lowered.

Fence Requirements

Longmont's fence rules in LMC 15.05.100 set construction standards: posts at least 4x4, embedded at least 24 inches deep and spaced no more than 8 feet apart; wood in contact with concrete or soil must be pressure-treated or naturally decay-resistant; finished side must face outward; fences may not block utility meters, fire hydrants, or easements; and the property owner must call 811 before digging.

Key details: Minimum Post Size: 4x4 nominal or larger. Post Depth: At least 24 inches embedded. Max Post Spacing: 8 feet. Wood Treatment: Pressure-treated or naturally decay-resistant when contacting concrete/soil. Finished Side: Must face ROW, common open space, or public area.

Fences with undersized posts, posts spaced more than 8 feet apart, or blocking meters/hydrants/easements may fail inspection. Digging without an 811 locate can result in utility damage charges and personal liability.

Material Restrictions

Under LMC 15.05.100, fences made of barbed wire, tin, or sheet metal - or partly of those materials - are prohibited. Electric fences are also prohibited, except for low-voltage commercially available 'invisible fences' used to contain domestic pets. Chain-link and woven-wire fencing is banned in the front yard of residential lots (except temporary construction fencing).

Key details: Barbed Wire: Prohibited (LMC 15.05.100). Tin / Sheet Metal: Prohibited - in whole or in part. Electric Fences: Prohibited, except low-voltage invisible pet fences. Razor / Concertina Wire: Prohibited (as form of barbed wire). Chain Link / Woven Wire: Prohibited in residential front yards (except temporary construction).

Installing prohibited barbed wire, tin, sheet metal, razor wire, or non-invisible electric fencing is a development code violation. Code enforcement can require removal and may issue municipal citations.

Compared to other cities, Longmont takes a harder line on material restrictions. The enforcement and penalty structure reflects that.

The Bottom Line

Longmont is tougher than many cities when it comes to fence regulations. Out of the 8 rules covered here, 3 are rated strict. If you are a homeowner, renter, or business owner in Longmont, take the time to understand these requirements before they become a problem. Most violations come with fines, and some repeat violations can escalate.

All of the above reflects Longmont's municipal code as of our last review. If you need specifics on fines, exemptions, or filing requirements, the detailed ordinance pages linked above have the full breakdown.