How do I prevent mice and rodents from getting into my garage in rural NB?

Preventing mice and rodents from entering your garage in rural New Brunswick comes down to one fundamental principle — sealing every gap larger than 1/4 inch (6 mm) around the entire perimeter of the structure, because a mouse can squeeze through any opening the size of a pencil, and NB's cold winters drive rodents aggressively toward any warm or sheltered structure from October through April. Rural NB garages are particularly vulnerable because they are surrounded by fields, woodlots, and brush that support large rodent populations, and a garage represents an irresistible combination of shelter, warmth, and stored food sources like birdseed, pet food, and garden supplies.

The garage door bottom seal is the single most common entry point for rodents. Inspect the rubber or vinyl seal along the bottom edge of every overhead door — if it is cracked, torn, compressed flat, or has gaps at the corners where it meets the door frame, mice are getting in. Replace worn seals with a new rodent-resistant garage door bottom seal, preferably one with a built-in metal retainer that mice cannot chew through. Universal replacement seals cost $20-$50 and install in under an hour by sliding into the retainer channel on the bottom of the door panel. While you are at the garage door, check the weatherstripping along the sides and top of the door — these vertical and header seals develop gaps over time as they compress and wear, and mice will exploit any opening.

The service door (man door) is the second most common entry point. Check the weatherstripping around all four edges and ensure the door closes tightly against the threshold. Install a door sweep on the bottom if there is not one already — a quality sweep with a flexible vinyl or rubber blade costs $10-$25 and closes the gap between the door bottom and the threshold. If the threshold itself has gaps where it meets the concrete slab, seal them with polyurethane caulk.

Next, inspect the entire exterior perimeter of the garage at ground level. Look for gaps where the siding meets the foundation, where utility pipes or wires enter the building, around dryer vents or exhaust fan openings, and at any penetration through the wall. Seal small gaps (under 1/2 inch) with steel wool stuffed tightly into the opening and covered with expanding foam or caulk — mice can chew through foam alone, but they will not chew through steel wool. For larger gaps around pipes, use galvanized steel mesh or hardware cloth (1/4-inch grid) cut to size and secured over the opening with screws or concrete anchors, then sealed with caulk around the edges.

Foundation-level entry points are common in older rural NB garages. Look for cracks in the foundation walls, gaps where the sill plate sits on top of the concrete, and any openings around the perimeter where the concrete has settled or crumbled. Fill foundation cracks with hydraulic cement or polyurethane caulk, and seal the sill plate-to-foundation joint with caulk or spray foam from the inside. In garages with stone or rubble foundations — still found on older rural NB properties — the gaps between stones are essentially open doors for rodents. These require extensive sealing with mortar or a combination of hardware cloth and hydraulic cement.

Soffit and fascia gaps are often overlooked but are common entry points, especially for squirrels and flying squirrels common in rural NB. Ensure all soffit panels are intact and secure, and that the fascia board sits tight against the roof sheathing with no gaps. Install metal soffit vent covers with fine mesh (1/4-inch maximum) over any ventilation openings.

Beyond sealing, reduce the attractants inside your garage. Store birdseed, pet food, grass seed, and garden supplies in sealed metal or heavy plastic containers — not paper bags or cardboard boxes. Keep the garage clean and clutter-free, as piles of stored items provide nesting habitat. Stack firewood outside the garage, at least 20 feet from the building and off the ground on a rack. Trim vegetation and brush away from the garage walls — maintain a clear zone of at least 2-3 feet around the entire perimeter so rodents cannot approach under cover.

For ongoing control, place snap traps (not poison bait) along walls and in corners inside the garage, checking and resetting them regularly through the fall and winter. Poison baits are problematic because rodents can die in wall cavities, creating odour and attracting insects, and poisoned rodents pose a risk to pets, owls, and hawks common in rural NB. This is entirely a DIY maintenance project — sealing a garage against rodents is well within any homeowner's capability with basic tools, caulk, steel wool, and hardware cloth, all available at your local building supply store.