Eastern Gray Squirrel
Sciurus carolinensis
In commercial settings — office buildings, retail premises, restaurants, institutional buildings, schools, and warehouses — eastern gray squirrel entry creates all of the same structural and safety risks as in residential buildings, with the added dimension of fire risk from gnawed wiring in occupied commercial premises.
Squirrel entry into food storage areas or food preparation spaces creates a contamination risk.
For commercial property managers, a squirrel-in-attic report should trigger a professional inspection and exclusion programme as quickly as possible. The cost of a small commercial exclusion job is a fraction of the cost of an electrical fire or a large-scale gnaw damage remediation.
Habitat
Commercial buildings in tree-lined settings or adjacent to parks, ravines, or naturalized areas face elevated squirrel entry risk. Buildings with flat roofs are not immune — squirrels gain access through mechanical equipment housings, conduit penetrations, and gaps in parapet coping.
Older commercial buildings with failing soffits and fascias are at high risk regardless of tree proximity, as deterioration creates entry opportunities that squirrels actively seek and exploit.
Active Areas
Windsor
Ubiquitous throughout all tree-lined Windsor neighbourhoods; consistently the most reported wildlife pest species in the city.
Tecumseh
High prevalence throughout residential areas with mature tree canopy.
LaSalle
High prevalence; mature residential tree canopy throughout the municipality supports dense gray squirrel populations.
Amherstburg
High prevalence; mature trees throughout established residential areas support a dense squirrel population.
Lakeshore
High prevalence; residential and rural wooded properties throughout the municipality.
Essex
High prevalence; urban and semi-rural properties with tree canopy throughout the municipality.
Kingsville
High prevalence; tree-lined residential areas support abundant gray squirrel populations.
Leamington
High prevalence; consistent with the regional pattern across all tree-canopied residential areas.
Chatham-Kent
Moderate prevalence in urban Chatham and larger towns in Chatham-Kent. Attic and soffit entry is the primary pest conflict.
St. Thomas
High prevalence in St. Thomas. Eastern gray squirrels are very common in mature urban trees and frequently enter attics.
Seasonality
Seasonal exclusion audits for commercial properties should be scheduled in late August or early September — before the fall entry window — to identify and seal vulnerabilities before squirrels exploit them.
Post-winter inspections in March are also advisable to identify any entry points exploited during the winter breeding season.
Spring
Summer
Autumn
Winter
Appearance
In commercial property inspections, gray squirrel entry point identification focuses on the roof-level and eave zones where the animal gains access.
Fresh gnaw marks around fascia gaps, soffits, and vent apertures are typically light-coloured (exposing fresh wood) and have a clean chisel-cut appearance. Old gnaw marks are darker and weathered.
The combination of daytime activity noise, visible entry points at the eave level, and the presence of nesting material (leaves, insulation shreds, paper) in the attic confirms gray squirrel infestation.
- Grey fur on the back and sides with a white or cream underside; the large, bushy grey tail with a white-frosted edge is the most recognisable feature
- The most common squirrel found entering Ontario homes and buildings — responsible for the vast majority of squirrel-in-attic calls in Windsor-Essex
- Enters attics through fascia board gaps, deteriorated soffits, open roof vents, gaps at the eaves, and where dormers meet the roof
- Chews continuously and must do so to control incisor growth — gnaws electrical wiring (creating a significant fire hazard), roof joists, insulation, and fascia boards
- Diurnal (active during the day) — noise from squirrels in the attic is heard primarily in the early morning and late afternoon
- Caches food across the property in autumn — flower bulbs, lawns, and garden beds may be dug repeatedly during fall caching behaviour
- Two breeding seasons per year (January–February and May–June) — the timing of litters influences when young squirrels attempt to enter buildings
Behaviour
In commercial settings, squirrel behaviour follows the same pattern as residential. The key commercial behaviour concern is the near-constant gnawing activity that occurs when squirrels are inside the building. Electrical conduits in attics, wooden roof joists, and any plastic or rubber materials are at risk.
Commercial roof inspections following a squirrel report should specifically look for gnaw damage to wiring, gas lines, and structural timbers as a priority safety check.
Lifecycle
Birth / Pup
In commercial buildings, pups in a nest within the roof space present the same timing problem as in residential settings.
A professional exclusion programme must assess whether a nest with young is present before any exclusion device is installed — this is standard professional practice and requires inspection prior to any work.
Juvenile
Juvenile squirrel activity in commercial settings follows the same pattern as residential.
Building inspections after the weaning and dispersal period (particularly in late April and again in September) should specifically check for fresh entry points created by exploring juvenile squirrels.
Adult
Adult squirrels in commercial settings are the primary concern for building managers — they are established, persistent, and will use the same entry point repeatedly until it is properly excluded.
Commercial exclusion of adult squirrels requires gnaw-resistant materials (heavy-gauge galvanised mesh, sheet metal flashing) and professional installation to prevent rapid re-entry.
An adult squirrel that has been using a particular entry point for an extended period may have created an established habit that makes it particularly persistent in attempting to re-enter at that location.
Signs You May Have a Problem
- Daytime scratching or bounding footstep sounds from attic or ceiling void spaces
- Gnaw damage to fascia, soffits, or roof vent screens, particularly at roofline junctions and eave returns
- Visible entry point at roofline level with displaced or chewed material around the aperture
- Nesting material and droppings found during attic or roof void inspections
- Gnaw damage to electrical wiring, conduits, or roof timbers discovered during maintenance inspections
- Urine staining or organic odour emanating from ceiling voids or attic spaces
- Staff reports of early-morning activity sounds from the ceiling or roof
Risks & Concerns
In commercial buildings, electrical gnaw damage in inaccessible attic or ceiling spaces represents the most serious risk — both the direct fire risk and the cost of tracing and repairing damaged wiring in a large commercial building can be substantial.
Food contamination in commercial food businesses is a regulatory and liability risk. Reputational damage from visible squirrel activity in a public-facing commercial premises is a secondary but real concern.
Prevention
- Commission an annual professional roofline and roof-level exclusion audit for all commercial properties — identifying and sealing vulnerabilities before squirrels enter is dramatically more cost-effective than post-entry remediation
- Ensure all rooftop HVAC equipment housings, conduit penetrations, gas line entries, and parapet openings are sealed with durable, rodent-resistant materials
- Maintain all exterior trees adjacent to the building with branches trimmed to a minimum 2-metre clearance from any roof surface
- Include squirrel exclusion inspection in the scope of any scheduled roofing or building envelope maintenance work
- Engage a licensed wildlife removal and exclusion company for any confirmed squirrel entry — Ontario's Fish and Wildlife Conservation Act governs the humane treatment and relocation of wild squirrels
DIY Control
- Commercial squirrel exclusion requires professional involvement due to the regulatory requirements, the building scale, and the safety implications of working at height
- Building management can facilitate professional work by providing access to roof spaces, documenting entry point locations, and clearing storage away from suspected entry points
Professional Control
- Professional commercial squirrel exclusion includes a comprehensive roofline and building envelope inspection, often using a lift or scaffolding for safe high-level access
- All entry points are sealed with commercial-grade galvanised mesh, metal flashing, and structural fasteners as appropriate to the building material
- Attic inspection for gnaw damage to wiring, structural elements, and insulation is included as part of the post-exclusion assessment
- A written exclusion report documents all entry points sealed, materials used, and recommended follow-up actions — this record is important for insurance and property management purposes