How do I rodent-proof and pest-proof my Ottawa garage?

Ottawa homeowners deal with mice, rats, squirrels, and various insects trying to get into garages every single fall and winter, and the problem is significantly worse here than in milder climates because our animals are highly motivated to find warm shelter when temperatures drop to minus 20 and below. A garage — especially one that is even slightly heated or attached to a heated home — is prime real estate for pests, and once they establish themselves, they chew wiring, contaminate stored items, damage insulation, and create health hazards from droppings and urine.

The most effective approach is exclusion first, deterrents second. Sealing entry points is the foundation of pest-proofing because no amount of traps or repellent will keep up with a population that has open access to your garage.

Start at the garage door. The bottom seal is the most common entry point for mice, which can squeeze through a gap as small as a quarter inch (roughly the diameter of a pencil). Inspect your bottom seal with the door closed — if you can see daylight underneath, mice can get in. Replace worn or compressed seals with a heavy-duty rubber or vinyl bottom seal, which costs $30 to $80 for materials. Add a threshold seal (an aluminum or rubber strip bolted to the concrete just inside the door) for a double seal that compresses against the bottom seal when the door closes — this adds $50 to $120 and dramatically improves the seal. Check the side and top weatherstripping too, as mice climb readily and will enter through deteriorated seals at any point around the door perimeter.

Next, inspect the exterior walls at ground level and where utilities enter. Mice commonly enter through gaps around water pipes, gas lines, electrical conduit, dryer vents, and HVAC ducts where they penetrate the wall. Seal gaps smaller than half an inch with steel wool packed tightly and covered with caulk — mice cannot chew through steel wool, but they will pull out caulk alone. For gaps larger than half an inch, use hardware cloth (1/4-inch galvanized wire mesh) cut to fit and secured with screws or concrete fasteners, then caulked around the edges. Hardware cloth also works well to cover soffit vents, gable vents, and any other openings that provide ventilation but also provide entry points for squirrels and birds.

The foundation-to-sill junction (where the wood framing sits on top of the concrete foundation) is another common entry point, especially in older Ottawa garages where the sill plate has shrunk or the concrete has cracked. Apply a continuous bead of polyurethane sealant along this junction both inside and outside. Check for foundation cracks wider than a quarter inch and fill them with hydraulic cement or polyurethane crack filler.

Inside the garage, reduce what attracts pests. Never store pet food, birdseed, grass seed, or garden fertilizer in original bags — transfer everything to sealed rigid containers (metal or heavy plastic with tight lids). Mice can chew through cardboard, thin plastic bags, and even some thicker plastic containers. Elevate stored items off the floor on wire shelving rather than cardboard boxes on concrete — this eliminates hidden nesting sites and makes inspection easier. Clean up any food-related debris and keep garbage cans sealed.

For ongoing deterrent and monitoring, snap traps remain the most effective and humane option for mice. Place them along walls (mice travel along edges, not through open floor space) with the trigger end perpendicular to the wall. Check and reset traps weekly during fall and winter. Avoid poison bait in garages — poisoned mice often die inside walls or in inaccessible spaces, creating horrible odours, and the poison can harm pets, children, or predator animals that eat the poisoned rodent.

For squirrels, which are aggressive in Ottawa neighbourhoods with mature trees, ensure all roof-level entry points are secured. Squirrels commonly enter through gaps where the roof meets the soffit, deteriorated fascia boards, and unscreened roof vents. Heavy-gauge hardware cloth secured with screws (not staples, which squirrels can pry out) is the standard fix.

A professional pest-proofing assessment and sealing of an Ottawa garage typically costs $500 to $1,500 and is worth every dollar compared to the ongoing frustration and damage of an unaddressed pest problem. Ottawa Garages can connect you with contractors who specialize in garage weatherproofing and exclusion work suited to our climate.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• Homeupgraders
• JC Carpentry
• Vanguard Environmental
• Joe Imerti Contracting
• Prism Services