Squirrels cause more property damage than most homeowners realize. They chew through roof materials, destroy insulation, and gnaw on electrical wiring, which can create a genuine fire risk. If you’re dealing with squirrel damage or trying to prevent it, here’s what you need to know about the types of damage they cause, how to identify it, and what it takes to fix.
How Squirrels Get Inside Your Home
Squirrels need an opening of about four inches in diameter to enter a structure. That’s smaller than a baseball. When they can’t find an existing gap, they create one by chewing through fascia board, roof shingles, and even plywood. Soffits, roof returns, and the joints where different rooflines meet are especially vulnerable because these areas often have small gaps that give squirrels a starting point to gnaw.
Once they’ve made an entry hole, moisture from rain and snowmelt follows them in. Homeowners commonly report water damage around the chewed opening, which compounds the structural problem and can lead to mold if the breach goes unnoticed for weeks or months.
The Real Dangers: Wiring, Structure, and Fire
The most serious risk from squirrels in an attic is electrical. Squirrels chew on wiring constantly because their teeth grow continuously and gnawing keeps them worn down. When they strip the insulation from electrical wires, they expose live conductors. That creates a direct risk of fire or electrocution. Rodents are estimated to cause up to 20 percent of undetermined house fires in the United States each year, and squirrels are among the most common culprits in attic spaces.
Beyond wiring, squirrels chew on structural components. Reports of gnawed 2x4s, damaged roof trusses, and weakened framing supports are common once squirrels have had free access to an attic for any length of time. They also shred stored documents, cardboard boxes, and soft materials to use as nesting material. Insulation is a favorite target. They’ll tear apart fiberglass batts and burrow into blown-in cellulose to build nests, reducing your home’s energy efficiency and contaminating the material with urine and droppings.
Yard and Garden Damage
Squirrel damage isn’t limited to your attic. In the yard, squirrels dig holes in lawns to bury and retrieve food caches, strip bark from ornamental trees, and raid vegetable gardens. Young trees are particularly vulnerable to bark stripping, which can girdle a trunk and kill the tree if the damage encircles it completely. Flower bulbs, especially tulips and crocus, are frequently dug up and eaten in fall and early spring.
How to Tell It’s Squirrels
Squirrel damage looks different from rat or mouse damage in a few key ways. The entry holes are larger, typically four inches across compared to the half-inch gaps rats can squeeze through. Chew marks on exterior surfaces tend to be rougher and more obvious, often visible on roof edges, siding, and fascia boards.
Droppings are another useful indicator. Squirrel droppings are oblong, up to half an inch long, and often contain visible bits of undigested food like seed fragments. Rat droppings are smaller (under a quarter inch), smoother, and more cylindrical. Both are dark brown to black, so size and texture are the distinguishing features. Squirrels are also less likely than rats to chew into food packaging indoors. If you’re finding gnaw marks on pantry items, rats are the more likely suspect.
Timing matters too. Squirrels are active during the day. If you hear scurrying and scratching in your attic in the morning or late afternoon, that points to squirrels. Nighttime noises are more likely raccoons, rats, or mice.
Health Risks From Squirrel Infestations
Squirrels carry fewer diseases transmissible to humans than rats, but they aren’t harmless. Their droppings and urine accumulate in attic spaces and can harbor bacteria and fungal spores. Breathing in dust from contaminated insulation during cleanup without proper protection is a real concern.
Squirrels also host parasites. Bot fly larvae, known as warbles, are commonly found in squirrels and appear as hairless lumps with a small breathing hole in the skin. While it’s rare for humans to develop warbles, pets can occasionally become accidental hosts. Squirrel fibroma virus (sometimes called squirrel pox) causes visible growths on infected animals but cannot spread to humans, cats, or dogs. Domestic rabbits are the one exception and can potentially contract it.
Fleas and ticks that squirrels carry can transfer to pets and people. A squirrel nesting in your attic essentially creates a parasite reservoir directly above your living space.
Legal Rules for Removal
Before you set a trap, know that squirrel removal is regulated in most states. In New York, for example, it’s illegal to live-trap a squirrel and release it anywhere other than the property where it was captured. Relocating wildlife to a park or public land is prohibited because it spreads diseases like rabies and Lyme and causes stress to the animal. Gray, black, and fox squirrels in New York require a permit from the Department of Environmental Conservation to remove as a nuisance outside of hunting season, and any animal taken during the closed season must be buried or cremated immediately.
Regulations vary by state and even by squirrel species, so your safest option is to contact a licensed nuisance wildlife control operator who knows the local rules. Red and flying squirrels often have different regulations than gray squirrels, even within the same state.
Exclusion and Prevention
The most effective long-term strategy is keeping squirrels out in the first place. Start with tree trimming. Cut back any branches within six to eight feet of your roofline. Squirrels are strong jumpers, and anything closer than that is essentially a highway to your roof.
Seal vulnerable entry points with materials squirrels can’t chew through. Heavy-gauge wire mesh works well over vents and soffits because it blocks access while allowing airflow. Metal flashing protects roof edges and fascia boards. Avoid using plastic or lightweight screening, which squirrels destroy quickly.
If squirrels are already inside, the standard approach is a one-way exclusion door installed over the main entry point after all other gaps have been sealed. This lets squirrels leave on their own but prevents them from getting back in. Timing matters here: if you seal a mother squirrel out during nesting season (typically late winter or midsummer), baby squirrels trapped inside will die in the attic, creating a new set of problems. A wildlife professional can assess whether young are present before starting exclusion work.
Repair and Restoration Costs
Fixing squirrel damage gets expensive quickly, especially if the infestation went undetected for months. Here’s what the major cost categories look like:
- Insulation removal and replacement: $2 to $6 per square foot for a straightforward swap. Most full projects run between $1,500 and $8,000 depending on attic size and insulation type.
- Attic cleaning: $300 to $1,500 or more depending on how much debris, nesting material, and old insulation needs to come out.
- Sanitation: $500 to $2,000 when droppings, urine, and odors need professional treatment.
- Rodent proofing: $500 to $2,500 depending on the number of entry points and extent of damage.
- Air gap sealing: $300 to $1,500 depending on penetrations.
- Full attic restoration: $4 to $10 or more per square foot when you combine removal, cleaning, sealing, rodent proofing, sanitation, and new insulation.
For a typical 1,000-square-foot attic that needs full restoration after a prolonged squirrel infestation, you could be looking at $4,000 to $10,000 or more. That doesn’t include electrical repairs if wiring was damaged, which may require a licensed electrician and adds another layer of cost. Structural repairs to chewed framing or water-damaged roof decking push the total higher still.
Homeowners insurance sometimes covers wildlife damage, but many policies exclude it or limit coverage. Check your policy language before assuming you’re protected. The faster you catch an infestation, the less it costs to fix.