Stop Using Spray Foam for Mice. They Eat It.
Mice chewing through your spray foam? Stop wasting money. Learn why you need steel wool or copper mesh to permanently seal rodent entry points.
It gets cold. You see a hole in the siding. You buy a can of "Great Stuff" expanding foam and spray it shut. You pat yourself on the back.
Two days later, there is a hole right through the foam.
Mice love expanding foam. It's soft, it's easy to chew, and it actually makes a nice warm insulation for their nest. You essentially just built them a front door.
The "Dime" Rule
If you can fit a pencil into a hole, a mouse can get in.
Mice have collapsible rib cages. They don't need a big opening. They just flatten out and slide through.
The Only Seal That Works: Copper & Steel
You have to physically hurt their teeth to stop them.
- Steel Wool (Grade 000): Stuff the hole tight with steel wool. Mice hate chewing it because the sharp fibers cut their gums.
- Copper Mesh: Even better. Steel rusts eventually; copper doesn't.
- The Caulk Cap: Don't just leave the wool exposed (they can pull it out with their claws). Seal over the steel wool with silicone caulk to lock it in place.
This is called "Exclusion." Traps kill the mouse inside. Exclusion stops the thousand mice waiting outside.