Fall pest-proofing comes down to sealing the gaps rodents and insects use to get inside before the first cold night: exterior cracks, foundation gaps, the dryer vent flap, clogged gutters, an open chimney, and the grill. Mice fit through a hole about 1/4 inch wide, so most of the work is finding and closing small openings, not setting traps.
Quick fall pest-proofing checklist
- Seal exterior gaps and cracks where utilities enter.
- Check the foundation for cracks and screen open vents.
- Confirm the dryer vent flap opens and closes.
- Clear gutters of nesting debris after the leaves drop.
- Cap and inspect the chimney before the first fire.
- Brush out the grill venturi tubes.
- Scan the roofline and soffits from the ground for gaps.
Seal exterior gaps and cracks
Walk the outside and look for openings around pipes, cables, and dryer and utility penetrations, and where siding meets trim. Mice get through a gap the width of a pencil, about 1/4 inch, so the CDC recommends packing small holes with steel wool and caulking over it, and using spray foam or hardware cloth on the bigger ones.
Check the foundation for cracks and gaps
Look along the base of the house and around crawlspace openings and utility entries. Patch small cracks with masonry caulk or mortar, and cover foundation and crawlspace vents with quarter-inch hardware cloth so rodents can't slip past while air still moves through.
Confirm the dryer vent flap closes
The exterior dryer vent is a common rodent door because lint props the flap open. Run the dryer and check that the flap swings open with the airflow and falls shut when it stops. A spring-loaded, pest-resistant vent cover fixes a flap that won't seat. Don't screen the opening shut, since trapped lint raises fire risk.
Clear the gutters of nesting debris
Packed leaves and twigs give insects and rodents a damp nest right against the roofline. Clear gutters in fall after the leaves drop, and confirm downspouts run free so water drains away from the foundation instead of pooling where it draws pests.
Cap and inspect the chimney
An open flue lets in birds, squirrels, raccoons, and bats, and a fall inspection catches nests and blockages before the first fire. A chimney cap with a screen keeps wildlife out. Have the cap fitted and the flue inspected by a CSIA-certified sweep rather than climbing onto the roof yourself.
Brush out the grill venturi tubes
Spiders and insects nest inside the venturi tubes of a gas grill over the warm months, and a blocked tube starves the burner and can push flames back toward the control panel. Run a venturi brush through each tube at the end of the season. If you smell gas or see lazy yellow flames, shut off the propane and stop using the grill until it's cleared.
Scan the roofline and soffits from the ground
Use binoculars to look for gaps in soffits, lifted flashing, loose fascia, and openings where the roof meets the wall, all routes for squirrels, bats, and wasps. Note what needs sealing and hire a roofer for the work instead of walking the roof to reach it.
If pests are already inside
Sealing the house reduces new entry; it doesn't clear out what's already there. If you have an active mouse, rat, or insect infestation, traps and pest control come first, then the sealing on this list so the same path doesn't get used again.
Good maintenance rhythm
The checklist gets you through fall sealing once. Keep pests out year after year by following a regular maintenance schedule.
- Fall, before the first freeze: seal exterior gaps, patch foundation cracks, and check the dryer vent flap.
- Fall: clear gutters after the leaves drop and confirm downspouts run free.
- Yearly: have a CSIA-certified sweep inspect and cap the chimney.
- End of grilling season: brush out the grill venturi tubes.
- Yearly: scan the roofline and soffits from the ground for new gaps.
- Ongoing: store firewood off the ground and away from the house, and keep pantry food sealed.