What role do garage doors play in winter pest prevention?

A garage door's bottom seal is a long, continuous strip of rubber or vinyl compressing against a concrete floor, and concrete floors are almost never perfectly flat or level across their full width. That unevenness means the seal compresses unevenly too — tightly in the middle, where the door is most rigid, and more loosely at the corners, where age and minor door-frame settling combine to open a gap first. The same logic applies to a torn or brittle astragal, the vertical seal at the sides: age causes it to crack and pull away from the frame at the ends before the middle gives out. None of this is a defect specific to any one garage door; it's simply how rubber and concrete interact over years of use.

Replacing a worn bottom seal is inexpensive and straightforward — most garage doors use a standard track-mounted seal that slides out and a new one slides in, no special tools required. While you're at it, check the side seals and the top header gap for the same wear pattern, and add a sweep to any separate service door into the garage, which is often overlooked entirely.

The reason this ranks as worth doing rather than a top-tier priority: an attached garage is unheated or only lightly heated, so it's a stepping stone into the house rather than the final destination for most rodents. But it is a stepping stone — mice that get into a garage through a corner gap often continue into the house through the door connecting the two, especially if the garage also holds pet food or birdseed. Storing anything edible in metal containers, not bags or bins, removes the incentive to linger.