Squirrels in Your Attic: Signs, Removal, and Prevention

Squirrels in your attic are loud, destructive, and surprisingly common in Ontario homes. They chew wood, insulation, and electrical wires — and they can stay for months if not addressed. Here is how to know what you are dealing with, why humane removal works, and how to prevent the next family from moving in.

How to know it’s squirrels (not bats, raccoons, or mice)

Most homeowners do not call us with a confirmed squirrel problem. They call with “something in the attic” and need help narrowing it down. Squirrels have a clear signature once you know what to listen and look for.

Sounds. Scampering and running across the attic floor during daytime — especially in the morning and again in the late afternoon — is the cleanest tell. Bats and raccoons are nocturnal; squirrels are diurnal. If the noise is loudest while you are eating breakfast or coming home from work, it is almost certainly squirrels. The footfalls are heavier than bats but lighter than raccoons. We cover the broader sound profile in our attic noise guide.

Sights. Watching a squirrel run up to a roof vent, soffit corner, or fascia gap and disappear is the most direct evidence you can get. Spend a few minutes outside in the morning and you will often see the access point yourself.

Damage. Fresh gnaw marks on wood trim, plastic vent screens, insulation, or wires. Squirrels must chew constantly — their incisors grow throughout life, and chewing keeps them in shape. If you see clean, light-coloured wood exposed under bite marks, that is recent activity.

Droppings. Squirrel droppings are about 3/8 inch, cylindrical, harder than mouse droppings, and usually light to dark brown. They get scattered across attic insulation rather than piled up. They are clearly different from the smaller, crumbly black pellets of bat guano.

Two species in Ontario. Eastern grey squirrels are the larger, more familiar species and often nest in tree hollows but use attics opportunistically. Red squirrels are smaller, more aggressive, and more likely to move into attics. Both behave similarly once they are inside.

Why squirrels in attics matter (the damage profile)

Squirrels are easy to underestimate because they look like backyard wildlife rather than a structural threat. The damage they cause inside a home is not minor.

Electrical damage. Chewed wires are the single biggest concern. Insurance investigators have traced attic fires back to squirrel-damaged wiring on more than one occasion, and a single nicked wire in old insulation is a slow-building risk you do not want sitting above your bedroom.

Insulation contamination. Urine and droppings accumulate in insulation across a season. The result is reduced R-value, persistent odour, and a layer of contaminated material that has to come out before new insulation goes in. Our attic decontamination service covers the cleanup side of this.

Structural damage. Chewed framing members, vents pulled apart, fascia widened from the inside, and rafters scored by claws are routine on jobs we open up. Roof penetrations from squirrels rarely heal themselves — they widen.

Smell. Urine soaked into insulation creates an odour that does not air out on its own. Several of our calls start with “I think there is something dead up there” when the actual issue is months of accumulated squirrel urine.

Multiple litters per year. Eastern grey squirrels typically have two litters per year — one in early spring and one in late summer — so an attic colony grows fast. Catching the issue at one entry point and one squirrel is a short job. Catching it after two litters and a winter of damage is a much bigger project.

How squirrels get in

Squirrels do not need much. About 1.5 inches across is enough — far smaller than they look. (For reference, bats need just half an inch, which is why our complete bat-proofing guide treats every gap as a potential entry.) The same handful of access points show up over and over.

Soffit corners. Squirrels can hook the lip of a soffit panel with their hands and pull a corner clean off, opening a gap big enough to climb through.

Roof vents. Plastic vent screens get chewed through; metal ones get pried off if the screws are loose or the housing is weak.

Roof flashing and fascia gaps. Small gaps where flashing meets shingle or wall get widened over time until a squirrel fits — same with seams where two fascia sections meet, or where the fascia meets the soffit.

Tree branches touching the roof. Squirrels run from trees onto roofs and then look for any weakness. Trimming branches back at least six to eight feet from the roof is one of the most effective preventive steps a homeowner can take.

Chimneys without caps. An open or damaged chimney is an easy drop-in den site, especially for spring litters.

How humane squirrel removal works

The process is similar in shape to bat and raccoon work, with timing and materials adjusted to squirrels.

Inspection. We walk the building and identify the primary access point — the one the squirrels are actively using — along with any secondary points that need to be sealed during the same job.

Account for litters. If it is spring or late summer, there is a high chance of non-mobile kits in the attic. We do not perform exclusions that would separate a mother from her kits. Either we wait until the kits are mobile (typically eight to ten weeks old) and the family can leave together, or we hand-relocate the family from the structure to a safe spot on the property. The goal is always to keep the family intact.

One-way device installation. We install squirrel-rated one-way doors at the primary access. The squirrel exits to forage, and the device prevents re-entry.

Verification. Verification typically takes three to seven days for adults to fully clear — much shorter than bat exclusion verification, which runs four to six weeks because of how colonies work.

Permanent sealing. Once the structure is empty, we seal every access point with materials a squirrel cannot chew through — heavy-gauge metal flashing, hardware cloth at 1/4 to 1/2 inch mesh, and structural wood replacement where damage occurred. Squirrels chew through plastic, screen, foam, and caulk. We do not rely on any of those.

Damage repair. Soffit, fascia, and vent replacement is often part of the same job. We fix the structure so the home is back to weather-tight, not just squirrel-free. Our wildlife removal service covers the full process across Owen Sound, Barrie, Collingwood, and the rest of our service area.

Why we don’t trap and relocate

A lot of homeowners assume “humane” means trap-and-release. It does not. Trap-and-relocate is the approach we have specifically chosen against, and the reasons are strong.

Most relocated squirrels do not survive. Adult squirrels rely on memorized food caches and known den sites to make it through an Ontario winter. Drop one in unfamiliar territory in October and it has no caches, no den, and loses territorial fights with the squirrels already there.

Mother-litter separation is a worst-case outcome. Trapping a mother and relocating her leaves her kits to starve in the attic. The “removal” leaves you with a much worse problem.

Ontario law restricts relocation. The Fish and Wildlife Conservation Act limits how far captured wildlife can be moved from the capture site. Driving a trapped squirrel “out to the country” is not a legal option for a property owner or a contractor.

It does not solve the problem. The access points are still open. A new squirrel discovers them within weeks because the structural issue is unchanged. Humane exclusion solves the problem permanently because the access points are closed with materials squirrels cannot defeat.

Prevention going forward

Once the structure is sealed, a few habits keep it that way.

Trim trees back six to eight feet from the roof. This is the single most effective preventive step. A squirrel that cannot reach the roof from a branch has to work much harder to find an access point.

Install chimney caps. A proper cap with stainless screen blocks chimney den sites without affecting draft.

Replace failed vent screens. Swap thin plastic or aluminum mesh for 1/4-inch galvanized hardware cloth. It costs more, but squirrels cannot chew through it.

Fix soffit and fascia gaps before they become problems. Our complete bat-proofing guide walks through the detail at the half-inch level for bats; squirrel-proofing uses the same logic but with heavier materials.

Annual exterior walk-through. Late winter is the right time — before spring litters arrive. Walk the perimeter and look for new gaps, lifted shingles, missing soffit screws, and chewed vent screens.

Same warranty principles. The wording our customers know is bat-specific, but the principles apply to all of our wildlife exclusion work:

If a bat re-enters through any point we sealed, we come back and do all the work necessary — at no extra cost. Forever.

The same lifetime warranty principles apply to our wildlife exclusion work. If any animal re-enters through a point we sealed, we come back and re-do the work at no extra cost. Full terms in our Terms of Service.

When to call

If you are hearing scampering in the attic during the day, seeing squirrels go in or out of the roof, or finding chewed wires or droppings, the right next step is a free on-site inspection. Call us for wildlife removal across Owen Sound, Barrie, Collingwood, and the rest of our service area. Every home is different — the inspection will tell you exactly what your situation needs.