How to Get Rid of Mice in Your House

How Mice Get In

Mice can squeeze through any gap that fits a pencil — about 1/4 inch. They don't need to chew their way in (though they can chew through wood, drywall, and even soft metals). Common entry points:

• Gaps where utility lines enter: Where gas pipes, water lines, electrical cables, and HVAC lines penetrate the foundation or exterior walls. Builders often leave oversized holes around these penetrations.
• Garage doors: The seal at the bottom and sides of garage doors degrades over time. Mice enter the garage first, then access the house through interior wall gaps.
• Dryer and exhaust vents: If the damper doesn't close completely or the vent hood has gaps around it.
• Foundation cracks and gaps: Where the sill plate meets the foundation, and at any crack or settling gap in the foundation wall.
• Weep holes in brick: Designed for moisture drainage, these are perfect mouse entry points.
• Under doors: Gaps under exterior doors and the door between the garage and house.
• Roof level: Mice climb walls, wires, and downspouts. Gaps at the soffit/fascia junction, around attic vents, and where rooflines meet walls are entry points at height.

Step 1: Set Traps Correctly

Snap traps remain the most effective mouse-killing method for homeowners. How to maximize their effectiveness:

• Placement: Set traps perpendicular to the wall with the trigger end touching the baseboard. Mice run along walls, not through open rooms. Place traps every 5–8 feet along walls where you've seen droppings.
• Quantity: Use more traps than you think you need. For a few mice, set 6–12 traps. Mice are cautious of new objects for 1–2 days, then investigate. You want traps available when curiosity overcomes caution.
• Bait: Peanut butter is the most effective bait — use a pea-sized amount pressed into the trigger. Mice have to work to get it off, triggering the trap. Don't use large amounts; mice will lick it off without triggering the mechanism.
• Behind appliances: Set traps behind the stove, refrigerator, and dishwasher — mice use the space behind appliances as highways.
• Keep traps out for 2 weeks minimum after the last catch. Mice you haven't caught yet may be avoiding the area where trapped mice were.

Avoid glue traps: They're inhumane (mice suffer for hours or days), they're messy, and they catch far less effectively than snap traps. If a non-lethal approach is important to you, use live-catch traps and release mice at least 2 miles away — closer than that, they'll return.

Step 2: Seal Entry Points (Exclusion)

This is the step most people skip, and it's the reason mice keep coming back. Trapping without sealing is like bailing water without plugging the hole.

• Steel wool + caulk: Stuff gaps with steel wool, then seal over it with caulk or expanding foam. Steel wool alone falls out; caulk alone gets chewed through. The combination is mouse-proof.
• Copper mesh: For gaps around pipes and in weep holes, copper mesh ("Stuf-fit" or similar) doesn't rust and mice can't chew it. Back it with caulk for permanence.
• Hardware cloth: For larger openings (vents, crawl space access), use 1/4-inch hardware cloth screwed into place.
• Door sweeps: Replace worn sweeps on exterior doors and the garage-to-house door. A mouse only needs a 1/4-inch gap under a door.

Step 3: Eliminate Food Sources

Mice stay where food is easy to find. A few changes make your home less attractive:

• Store pantry food in glass or heavy plastic containers — mice chew through cardboard, thin plastic, and paper bags easily
• Clean behind the stove and refrigerator where food debris accumulates
• Don't leave pet food bowls out overnight
• Keep bird seed in sealed containers and clean up spilled seed under feeders
• Take out garbage daily during an active mouse problem

Signs You Need Professional Help

Consider professional rodent control ($300–$600 for exclusion and trapping) when:

• Droppings are in multiple rooms or on multiple floors — this suggests multiple entry points and a larger population
• You find nesting material (shredded paper, fabric, insulation) — mice are breeding inside your home
• You hear scratching or running in walls or ceiling — mice are traveling through wall cavities
• You've been trapping for 2+ weeks with continued catches — new mice are entering as fast as you trap
• DIY sealing hasn't stopped the problem — a professional exclusion inspection finds entry points you've missed

Professional exclusion involves a thorough inspection (often using UV tracking powder or other detection methods), sealing all identified entry points with commercial-grade materials, and strategic trapping. Most companies offer a warranty: if mice return within 6–12 months, they return and reseal at no cost.

Health Concerns: Clean Up Safely

Mouse droppings and urine can carry hantavirus (primarily deer mice in rural areas), salmonella, and other pathogens. When cleaning up droppings:

• Don't sweep or vacuum droppings — this aerosolizes particles
• Spray the area with disinfectant or a 10% bleach solution and let it sit for 5 minutes
• Wipe up with paper towels and dispose in a sealed bag
• Wear gloves and wash hands thoroughly after cleanup