How to Seal Your Home Against Mice

Mice are expert opportunists that treat your home's perimeter as a buffet of potential shelter. A hole the size of a ballpoint pen is enough for a mouse to squeeze its entire body through, making the structural integrity of your foundation, siding, and utility penetrations your first and best line of defense. Successfully excluding rodents isn't about traps; it's about closing the door. When you do this well, you stop the problem before it enters your living space. Focus on the transition points—where wood meets concrete, where pipes enter the wall, and where siding meets the foundation—because if air can pass through, a mouse can eventually chew its way in.

1. Spot Every Rodent Gateway. Walk the entire exterior of your house with a bright flashlight. Check for gaps where siding meets the foundation, around vents, and where utility lines like gas or electric enter the building.
2. Block With Steel Wool. Pack steel wool tightly into any hole larger than a quarter-inch. Use copper mesh for exterior applications where rust could cause staining on your siding.
3. Lock It Down Permanently. Apply a thick bead of exterior-grade silicone caulk over the packed steel wool to hold it in place and weather-seal the area. Ensure the sealant completely covers the mesh edges.
4. Fortify Vent Screens. Check all crawl space and foundation vents for damaged screening. Replace torn screens with 1/4-inch hardware cloth, secured with galvanized screws.
5. Seal Garage Door Thresholds. Inspect the rubber weather stripping at the bottom of your garage doors for cracks or gaps. If it is dry-rotted or uneven, install a new heavy-duty rubber seal.
6. Eliminate Climbing Routes. Trim all tree branches back at least 6 feet from your roofline and clear dense shrubbery at least 18 inches away from the foundation walls.