How to Keep Mice Out of Your House for Winter (My One-Afternoon Fix)

 

First cold snap of the year is when mice start shopping for a warm house, and apparently mine had good reviews. I found droppings along the garage wall and decided I'd rather spend one afternoon sealing the place up than spend all winter setting traps.

The thing nobody tells you: a mouse can squeeze through a hole about the size of a dime. A quarter inch. If you can poke a pencil through a gap, a mouse can probably get through it. That's why traps alone never fix the problem — you're catching them one at a time while the door is still wide open.

The walk: I went around the outside of the house with a flashlight and actually looked. The gaps are always in the same places: where pipes, wires, and the AC line come through the wall, the bottom corners of the garage door, cracks along the foundation, the dryer vent, and the gap under the back door threshold. I found six spots in twenty minutes. Six open doors.

The fix: stuff every gap tight with copper mesh. Copper works for two reasons: mice can't chew through it, and unlike steel wool it doesn't rust into dust after one wet season outdoors. Cut it with regular scissors, pack it in with a screwdriver. On the bigger gaps I stuffed the mesh in first and sealed over it with exterior caulk. Don't use expanding foam by itself — mice treat spray foam like a snack with a door in it.

Inside counts too: dry goods and pet food went into hard containers, and I stopped leaving the dog's bowl full overnight. No food, no reason to stay.

The honest part: skip the peppermint oil routine. It makes the garage smell like a candy cane and does almost nothing by itself. I also tried one of those ultrasonic plug-in gadgets a few years back; the mice were not impressed. And if mice are already living in your walls, trap them out first, then seal. Seal first and you've just locked them in with you.

The whole job took one afternoon, and one roll of mesh covered every gap I found with some left over. No droppings since, and it cost less than a single exterminator visit. Same lesson as the $5 toilet fix and the drafty windows: the cheap, boring fix is usually the real one.

Heads up: the mesh link above is an affiliate link. If you buy through it, I earn a little at no extra cost to you.