Squirrels in the Attic in Colorado: What They Chew and How to Get Them Out

In the Denver metro and along Colorado's Front Range, fox squirrels are year-round residents. They live in the big cottonwoods along drainage ditches, in neighborhood parks from Arvada to Aurora, and along the Platte River greenbelt. They are adaptable, bold, and persistent about finding shelter. A fox squirrel's front teeth grow roughly six inches per year and never stop. That biological fact explains everything about what happens when one gets into your attic: it chews because it has to, not because it is destructive for the sake of it. Wood framing, rigid foam, plastic plumbing pipe, and the insulation sheathing on your electrical wiring all register as suitable chew material.

The wiring part matters most. Stripped wire insulation in an attic can arc against dry wood framing or blown-in insulation and start a fire, sometimes days or weeks after the initial damage. That is the part of a squirrel infestation that insurance adjusters and fire investigators take seriously, and the part that makes prompt action worth the effort.

This post covers what squirrels damage in Colorado attics, when the two nesting seasons fall, and how licensed technicians use exclusion (sealing entry points and one-way doors) to remove them permanently and humanely.

What Squirrels Actually Chew in a Colorado Attic

Fox squirrels and Abert's squirrels, both common in Colorado's urban and foothills areas, will chew through most of the materials found in a typical attic. Electrical wiring is the highest-stakes target because the damage is invisible until something goes wrong.

The United States Fire Administration has linked approximately 25,000 residential fires per year to rodents gnawing on electrical wiring. Squirrels are among the most common attic-dwelling species involved. A single section of stripped wire where bare copper contacts nearby combustible insulation is all it takes to create an arc condition. That arc may be intermittent at first, charring surrounding material before a full ignition event occurs.

Beyond wiring, attic squirrels in Colorado homes also:

• Gnaw through roof decking and rafter members, weakening structural connections over time
• Shred blown-in cellulose or fiberglass insulation to build nests, which cuts your attic's thermal performance and drives heating costs up
• Chew plastic water supply lines, leaving slow leaks behind walls that may not surface for months
• Contaminate insulation with urine and droppings, creating persistent odor and a low but real leptospirosis exposure risk
• Cache food, particularly acorns and seeds, in corners of the attic that then attract secondary pests

Not all of that damage is visible from the attic hatch. A thorough inspection covers the wiring runs along the eaves, the framing directly above exterior walls, and every board near the original entry point. Those are the spots that take the most abuse in the first weeks of an infestation.

Is the Fire Risk Really That Serious?

Yes. The fire risk from chewed wiring is the part of squirrel damage that homeowners most consistently underestimate. When insulation is stripped from a 14-gauge wire, the bare copper can arc against adjacent materials. Attic insulation, dry framing lumber, and old construction paper vapor barriers are all ignitable at low arc temperatures. The arc may happen only occasionally at first, charring a small area before conditions align for a sustained fire.

An electrician doing a post-removal inspection sometimes finds conductors with bite marks that did not cause a fire only because the arc happened to travel away from combustibles. That is a matter of chance, not safety margin.

The practical takeaway: if squirrels have been active in your attic for more than a few weeks, have a licensed electrician inspect the wiring after the animals are removed. Many homeowner's insurance policies cover wildlife damage, but some carriers require written documentation of a wiring inspection before approving a claim. Check with your agent before the removal work begins, not after.

Colorado's Two Squirrel Nesting Seasons

Fox squirrels in Colorado breed twice annually. According to Colorado Parks and Wildlife (cpw.state.co.us), the primary seasons fall roughly from late February through early April and again from July through August. During those windows, females search actively for enclosed, dry, predator-resistant spaces to give birth and raise young. An attic meets every one of those criteria.

The timing matters for removal planning. A female with pups in the nest will not leave voluntarily. If a one-way door is installed while young squirrels are still inside and too small to follow her out, she will work aggressively to re-open the entry point, sometimes causing more damage in an hour than she caused in the previous week. An experienced technician checks for the presence of young before installing any exclusion device. The check involves listening for vocalizations, looking for nesting material concentration, and sometimes using an attic camera in hard-to-reach corners.

Outside of breeding seasons, squirrels still use attics year-round as food caches and cold-weather shelters. Colorado's temperature swings between December and March push squirrels toward any enclosed warm space they have already found. A problem that seems mild in October often intensifies by January.

How Does Professional Squirrel Removal Work in Colorado?

The professional standard is exclusion, not trapping. Exclusion means sealing every entry point except one or two, then installing a one-way door (sometimes called an exclusion funnel) at those remaining openings. The device lets squirrels exit to forage normally but prevents them from re-entering. Within five to ten days, all animals inside have left on their own. The technician returns, removes the devices, and permanently seals the final openings.

No trapping. No relocation stress. No separating a mother from dependent young when the job is done correctly.

The steps in order:

• Full perimeter inspection: Every gap on the roofline is documented. Fox squirrels can pass through an opening as small as 1.5 inches, roughly the diameter of a golf ball. Any gap at that size or larger becomes a potential entry point.
• Secondary sealing: All entry points except the primary one are closed with galvanized hardware cloth, aluminum flashing, or copper mesh, depending on the material and location of the gap.
• One-way door installation: A quality one-way funnel or tube device is attached at the main entry point. Animals exit freely and cannot push back through in the opposite direction.
• Monitoring period: Five to ten days. Signs of activity around the device (fresh gnaw marks on the frame, disturbed material at the entry edge) indicate animals are present and still attempting re-entry.
• Final seal and removal: Once activity stops, the device comes off and the opening is permanently closed.

The full process from first visit to final seal typically takes one to three weeks. Homes in older neighborhoods in Lakewood, Westminster, or Fort Collins where rooflines have weathered several Colorado winters often have more secondary entry points and run toward the longer end of that range.

What About Live Trapping?

Live trapping is sometimes useful as a supplemental step, particularly when young squirrels are present and need to be relocated to a safe nearby location with their mother, or when exclusion hardware is impractical on one section of the structure. Trapping alone, without sealing the entry points, does not solve the problem. New squirrels will find and use the same openings within a few weeks.

Fox squirrels and Abert's squirrels are regulated wildlife in Colorado, and Colorado Parks and Wildlife (cpw.state.co.us) sets the rules for how and when they can be trapped or moved. Homeowners should not assume trapping and relocating them is unrestricted. A licensed removal company handles the permitting questions and ensures any trapping stays inside state rules. Releasing squirrels into unfamiliar territory far from where they were captured is also not a good outcome for the animal, which is one reason exclusion-first is the professional standard.

Poison is not a tool for squirrel removal. It carries secondary poisoning risk for red-tailed hawks, great horned owls, foxes, and neighborhood pets. It also leaves carcasses inside wall cavities and ceiling spaces where they are impossible to retrieve, causing weeks of odor and fly activity that is expensive and unpleasant to address.

Sealing for Good: What Actually Keeps Squirrels Out Long-Term

Exclusion done correctly is durable, but it requires the right materials. Standard caulk, wood filler, and expanding foam are not adequate by themselves. Squirrels will chew through or around them within a season. Effective permanent sealing uses:

• 16-gauge galvanized hardware cloth: Stapled and then covered with aluminum or galvanized flashing to prevent edge gnawing
• Copper mesh: Packed into irregular gaps where flat hardware cloth will not conform; squirrels do not chew copper
• Aluminum flashing: Applied over wood joints at roofline transitions where boards meet and gaps can form as wood moves seasonally
• Steel-screened vent covers: The plastic factory covers on gable vents and soffit strips are easily chewed; steel replacements last

A reputable technician will also flag conditions that make re-entry likely within the next season or two: overhanging branches within eight feet of the roofline, rotting fascia boards, or missing drip edge that channels water and animal traffic behind the first row of shingles. Trimming back any tree branches to at least eight feet from the roof removes the squirrel's main route onto the house. In neighborhoods with large cottonwoods and box elders, like many parts of Boulder and Longmont, that branch-trimming step is as important as the hardware work.

What Does Squirrel Removal Cost in Colorado?

Costs vary by the size of the structure, the number of entry points found, and whether the job includes attic cleanup, insulation remediation, or a separate electrical inspection. As a general range, straightforward jobs on smaller homes run a few hundred dollars; larger homes with multiple entry points, significant nesting contamination, or unusual roofline complexity can exceed a thousand dollars. Any company worth hiring offers a free on-site inspection before quoting because there is no honest way to price a job from a phone call alone.

Some jobs qualify for homeowner's insurance coverage when damage is documented correctly. Ask about that at the inspection. A thorough technician can walk you through what documentation your carrier typically needs for a wildlife damage claim.

Frequently asked questions

Related reading

• What Is That Scratching in Your Attic?
• Wildlife Removal Costs in Colorado
• Signs of Wildlife in Your Attic