squirrel exclusion roof vent cover

Case Study: Squirrels Enter Attic by Damaging Roof Vents in Thornhill

The following case study tells the story of a squirrel removal job in Thornhill. This article will analyze and recount the squirrel removal process from the customer’s attic. It will detail the steps taken in inspection, exclusion, and prevention by the technician, to permanently remove a squirrel from the attic. This was located in Thornhill, Vaughan between Steeles Ave and Highway 71.

The technicians, before the exclusion, must first inspect and confer with the customer or customers on the issue and then must inspect for levels of activity. The customer’s original complaint was that a squirrel had penetrated a soffit, making a clear and apparent entryway. A technician was sent out to inspect the entryway and to exclude the animal with a one-way door.

Thornhill, Vaughan: A park filled suburb

Thornhill is a city divided. Half of the city is Vaughan and the other half is Markham. In truth, Thornhill no longer exists but is maintained in common use. The key to the advancement of this very old neighbourhood was the construction of a military road connecting Holland Landing to the waterfront of Toronto. This was achieved by offering new settlers a free 200-acre plot of land if they cleared the way for the road it would eventually be up against. This helped not only to build the road in record time but populated a large stretch of space all the way from Toronto to Lake Simcoe. This road has since been the site of constant activity and construction from the mid-1800s to the present, many churches, houses and businesses developed along this specific road on which stagecoaches would ferry people from Simcoe to York.

Exterior Inspection

The technician arrived on site and began the exterior inspection of the roof of the customer’s house. The main entryway was found to be accessed through a roof vent, the damage caused by the animal was clear. The squirrel chewed through the plastic to create a hole straight through the front of the vent. There were six other roof vents that required exclusion as well as two plumbing vents. Plumbing vents are also plastic and are thus easily breachable by both raccoons and squirrels.

Chewed Roof Vent Squirrels
Squirrels have teeth that are strong enough to chew through wood, plastic, rubber, and thin metals.
Squirrels Chewed Roof Vent Thornhill
In this case, squirrels chewed right through a roof vent to access the attic.


Initial Measures

The technician must humanely remove the squirrel from the attic. This is done with the use of a one-way door. The door is built in such a way that it allows the animal to vacate but clamps shut and cannot be opened from the other side.

Proposed Exclusion

The one-way door used to humanely evict the animal from the attic was attached to the chewed hole through the roof vent. A galvanized steel cage was used to protect the vent from access. Seven roof and attic vents were compromised or in danger of being compromised and were excluded with rubber-coated galvanized steel mesh. Plumbing vents and three feet of soffit were also found to be accessible by the squirrel and were closed off.

Squirrel One Way Door on Roof Vent
One-way doors are incredibly effective for removing squirrels as they let them out and stop them from coming back.
Plumbing Vent Squirrel Exclusion
The rubber mat at the base of the plumbing vent is vulnerable to squirrels and other wildlife.
Roof Vent Covers Squirrel Exclusion
Covering the other roof vents would prevent any more squirrels from getting into the attic.
Soffit Reinforcement Squirrel Proofing
The soffits were also reinforced with mesh to prevent any other animals from breaking through.


The one-way door was effective in evicting the squirrel from the attic. The one-way door allowed the squirrel to vacate by lifting a section of steel mesh, when the mesh falls back down it becomes difficult for the squirrel to move and locks them out of their nest. The exclusion of the roof vents and soffit intersections will protect the roof from further animal invasion. The exclusion of the plumbing vent and the rest of the roof vents means that the squirrel will not be able to find an area it can chew to get back inside the attic. Protecting these vulnerable areas is of crucial importance in keeping squirrels and raccoons out for the long run.

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