As the leaves start to turn in Louisville, mice start looking for a winter home. They don’t need an open door to move in; an adult mouse can squeeze through a hole the size of a dime (1/4 inch).

Many homeowners set traps but fail to seal the entry points. This is a losing battle. You might catch five mice, but five more will just follow the scent trail right back inside. To solve a mouse problem, you must seal the “building envelope.”

Here is a professional checklist of the most common entry points we find in Louisville homes.

1. The A/C Line Penetration

Go outside to your air conditioner condenser unit. Follow the copper refrigerant lines to where they enter the side of your house. Is the putty or foam around the pipe rotted away?

• The Fix: Do not use spray foam alone (mice chew right through it). Stuff the gap tightly with copper mesh (Stuf-Fit) or steel wool, then seal over it with exterior-grade caulk. Copper mesh is superior because it doesn’t rust.

2. Garage Door Corners

Stand inside your garage with the lights off during the day. Look at the bottom corners of the garage door. Do you see daylight? If you see light, a mouse can get in.

• The Fix: Replace the rubber weatherstripping on the bottom of the door. If the mice have chewed the wooden frame, install metal “rodent guards” or flashing on the corners.

3. Foundation Vents & Crawl Space Doors

If you have a crawl space, check the vents. Are the screens intact? Mice often chew through old, rusty screens.

• The Fix: Install new 1/4-inch hardware cloth (steel mesh) over the vents. Ensure the crawl space door fits tightly and has no gaps larger than 1/4 inch.

4. Utility Pipes (Gas & Water)

Check where gas lines and water spigots enter the foundation. These penetrations often have gaps that were never properly sealed during construction.

• The Fix: Seal with copper mesh and caulk or hydraulic cement.

5. Dryer Vents

Exterior dryer vents should have a louvered cover or a cage. If the louvers are stuck open with lint, mice (and birds) can climb straight into your laundry room.

• The Fix: Clean the lint and install a rodent-proof vent cover.

6. Rooflines and Soffits

Mice are excellent climbers. They can scale brick walls and trees to reach your roof. Check for gaps where the soffit meets the brick or where different rooflines join.

• The Fix: This often requires ladder work. Seal gaps with metal flashing or sealant.

7. Weep Holes

Brick homes have small vertical gaps near the foundation called weep holes to let moisture escape. While necessary for the brick, they are perfect mouse doors.

• The Fix: Do NOT caulk these shut (it will cause mold). Install specialized “weep hole covers” or stainless steel mesh inserts that allow airflow but block mice.

Why “Copper Mesh” is the Secret Weapon

Professional exterminators rarely use plain steel wool. Steel wool rusts when it gets wet, eventually crumbling away and leaving rust stains on your siding. Copper mesh (often sold as Stuf-Fit) never rusts, is impossible for rodents to chew through, and is easy to stuff into cracks with a screwdriver.

If you seal these 7 areas, you will eliminate 90% of mouse problems before they start. If you’re already hearing scratching in the walls, call Critter Removal of Louisville. We can perform a full exclusion inspection and trap the mice already inside.