Most people picture a mouse squeezing in through some hidden crack in the foundation. In garages, the far more common entry point is right at the bottom of the door — a rubber seal that's supposed to close the gap completely, but rarely does once it's worn.
Why The Gap Matters More Than It Looks
Mice don't need much room. A healthy adult mouse can squeeze through an opening roughly a quarter of an inch wide — about the width of a standard pencil. A garage door seal that's flattened, cracked, or pulling away from the door doesn't need to fail dramatically to create that much of a gap; a small amount of wear is often enough.
Why This Particular Seal Wears Out
The bottom seal takes more abuse than almost any other part of a garage door. It compresses against the driveway every time the door closes, gets dragged across grit and debris, and is exposed to temperature swings that make rubber brittle over time. Uneven driveway surfaces make this worse, since the seal has to compress unevenly along its length, leaving small gaps at the corners even when the center looks fine.
How To Check Your Own Seal
With the door closed, look along the entire bottom edge from inside the garage, checking specifically at both corners where compression is often weakest. A flashlight test at night — turning off garage lights and checking for daylight visible underneath — is a simple way to spot gaps that aren't obvious just by looking. If you can see light, a mouse can very likely get through.
Replacing a worn seal is a relatively small repair compared to what it costs to deal with mice that have already established themselves in stored boxes, insulation, or a vehicle. Beyond the seal itself, checking for other gaps — around utility penetrations, garage-to-house doors, and vents — rounds out a full garage pest control approach rather than fixing just the one obvious spot.
If mice are already active, our rodent exclusion services team can handle both the removal and the seal replacement in the same visit.
A garage door seal is easy to overlook because it's doing its job most of the time. Checking it before it fully wears out is a lot cheaper than fixing what gets in once it does.