How to Keep Mice Out of Your Garage (Entry Points + Storage Fixes)

Your garage is one of the easiest places for mice to move into — and one of the easiest to protect. Garages are full of everything mice want: shelter, nesting material, crumbs, pet food, and dozens of tiny entry points. Once mice settle in your garage, your house is usually next.

The good news is that keeping mice out of your garage is mostly a weekend project. It comes down to two things: sealing the entry points they use to get in, and removing the food and shelter that make them want to stay.

Why Mice Love Garages

A mouse can squeeze through a hole the size of a dime — about 1/4 inch. Most garages have far bigger gaps: the corners of the garage door seal, gaps where pipes and cables pass through walls, vents without screens, and the space under side doors. Inside, they find cardboard boxes full of nesting material, bags of grass seed or pet food, and warm hiding spots behind stored items and appliances.

Mice also use garages as staging areas. A mouse living in your garage is a mouse scouting your kitchen. Sealing the garage protects your whole house.

Step 1: Find and Seal Entry Points

Do this inspection at dusk with the garage door closed and the lights on inside. Walk around the outside and look for light leaking out — anywhere light escapes is a gap a mouse can enter.

Seal the garage door edges

The bottom corners of the garage door are the #1 mouse entry point. Check the rubber weather seal along the bottom of the door — if it’s cracked, chewed, or doesn’t sit flat on the floor, replace it. Add brush-style or vinyl seals to the sides and top of the door frame. For stubborn corner gaps, hardware stores sell garage door rodent guards that fit the bottom corners specifically.

Close gaps around pipes, cables, and vents

Wherever a pipe, cable, or conduit passes through a garage wall, there’s usually a gap around it. Fill small gaps with copper mesh or steel wool, then seal over them with caulk or expanding foam. Never use foam alone — mice chew straight through it. The metal mesh is what stops them; the caulk just weatherproofs it. Cover vents and exhaust openings with 1/4-inch hardware cloth.

Fix the side door and windows

Garage side doors often have worn weatherstripping and a gap underneath. Replace worn stripping and install a door sweep. Check window frames for cracked caulk and reseal them.

Don’t forget the wall-to-house connection

The door between your garage and your house should be solid, self-closing, and weatherstripped. Check the shared wall for gaps around pipes and wiring too — this is the barrier that keeps garage mice out of your living space.

Step 2: Remove Food Sources

• Store pet food, bird seed, and grass seed in sealed metal or heavy plastic containers. Mice chew through paper and thin plastic bags easily.
• Clean up crumbs and spills. Sweep the garage floor regularly, especially around workbenches and storage areas.
• Secure trash cans with tight-fitting lids. If you keep garbage in the garage between pickups, use cans mice can’t chew through.
• Pick up fallen fruit if you store produce or have fruit trees near the garage.

Step 3: Fix Your Storage Habits

Cardboard boxes are mouse hotels — they’re chewable, warm, and full of nesting material. Replace cardboard storage boxes with hard plastic bins with locking lids. Keep bins and items stored at least a few inches off the floor and a few inches away from walls where possible; this removes hidden runways and makes droppings easier to spot.

Declutter. Piles of old newspapers, rags, fabric, and junk are nesting gold. The less clutter, the fewer hiding spots — and the faster you’ll notice droppings or gnaw marks if a mouse does get in.

Step 4: Make the Garage Less Inviting

• Trim vegetation back from the garage walls — bushes and vines touching the building are mouse highways.
• Keep firewood and lumber stacked away from the garage, at least 20 feet away and off the ground.
• Reduce moisture. Fix leaks and improve drainage; mice, like all pests, prefer damp shelter.
• Keep the garage door closed as much as practical, especially at night when mice are most active.

The Complete Garage Door Seal Walkthrough

The garage door is the largest opening in your garage and the most common mouse entry point. Here’s how to mouse-proof it thoroughly, step by step.

Inspect the bottom seal

With the door closed, crouch down and look along the entire bottom edge from inside (with the lights off, this is easier — daylight leaking in marks every gap). The rubber or vinyl astragal seal should press firmly and evenly against the floor along its full width. Look for cracked, brittle, chewed, or flattened sections, and check whether the concrete floor itself is uneven — low spots create gaps even a new seal can’t bridge.

Replace a worn bottom seal

Bottom seals slide into a retainer channel on the door’s bottom edge. Measure your door width, buy a replacement seal of matching profile (T-shaped and bulb-shaped are the common types), slide out the old one, and feed in the new one. It’s a 20-minute job with no special tools. For uneven floors, consider a threshold seal — a raised rubber strip glued to the floor that the door closes against, which conforms to dips and bumps.

Seal the sides and top

Vinyl or brush weatherstripping nailed to the door jambs presses against the door’s edges when closed, blocking the side gaps mice exploit. Brush-style seals are especially good — the dense bristles block rodents while flexing with the door’s movement. Don’t forget the top of the door frame, where a surprising gap often hides.

Guard the bottom corners

The bottom corners where the door meets the jambs are the toughest spots — the door’s geometry leaves small triangular gaps there. Hardware stores sell purpose-made garage door rodent guards: angled metal or heavy rubber shields that close these corners. Combined with a fresh bottom seal, they eliminate the #1 mouse highway.

Fall Is Mouse Season: Time Your Defense

Mouse invasions spike in fall. As temperatures drop, field mice seek warm winter shelter — and your garage is prime real estate. The smart move is to complete your sealing work in late summer or early fall, before the migration starts.

• August–September: do your sealing, storage upgrades, and decluttering. Set a few snap traps as sentinels even if you’ve seen no signs — early detection beats late discovery.
• October–November: check traps weekly and watch for droppings. Mice that get in now will try to overwinter.
• Winter: keep the garage door closed as much as possible and don’t store bird seed or pet food in the garage — winter is when these attractants matter most.

A garage sealed before fall stays mouse-free all winter with minimal effort. A garage sealed in January is closing the barn door after the mice moved in.

What About Traps and Poison?

Sealing and sanitation are your first and best lines of defense. If mice are already inside, snap traps placed along walls (mice travel along edges, not across open floor) baited with peanut butter are the fastest, most humane DIY option. Check traps daily.

If you consider rodent bait products, follow EPA safety guidance carefully: use tamper-resistant bait stations only, never scatter loose pellets where children, pets, or wildlife can reach them. Bait stations must be secured and labeled, and dead rodents should be disposed of with gloves in sealed bags. Where children or pets are present, traps are the safer choice.

How to Tell If Mice Are Already in Your Garage

• Droppings: small, dark, rice-grain-shaped pellets along walls, in corners, and near stored food.
• Gnaw marks: on boxes, wiring, wood, or plastic containers.
• Nesting material: shredded paper, fabric, or insulation tucked into corners or boxes.
• Tracks: tiny footprints in dusty areas.
• Smell: a stale, musky odor in enclosed areas.

If you find active signs, set traps first, then seal entry points after you’ve caught the current residents — sealing mice inside just traps them in your garage.

What to Do If You Find a Mouse Nest in the Garage

Discovering an active nest means mice have already moved in. Here’s how to handle it:

1. Gear up: wear gloves and a dust mask — mouse droppings and nesting material can carry hantavirus and other pathogens. Never sweep or vacuum droppings dry; this aerosolizes particles.
2. Disinfect first: spray droppings and nesting material with a disinfectant or a bleach-water solution (1 part bleach to 10 parts water) and let it soak for 5 minutes before wiping up with paper towels.
3. Double-bag and discard all nesting material, droppings, and contaminated items in sealed bags in outdoor trash.
4. Set snap traps along the walls near where the nest was — where there’s one nest, there are usually more mice nearby.
5. Find how they got in. A nest means an entry point is open. Do the dusk light-leak inspection described above and seal every gap before the next mouse moves in.

If you find extensive contamination — droppings throughout stored items, strong odor, or nests inside wall voids — consider calling a professional. Heavy infestations can require cleanup beyond DIY scope.

Frequently Asked Questions

Can mice really get through a hole the size of a dime?

Yes. An adult mouse can squeeze through a gap as small as 1/4 inch (about 6mm) because their skulls are flexible and their bodies compress. If a pencil fits through a gap, assume a mouse can too.

Do ultrasonic repellers keep mice out of garages?

Evidence for ultrasonic repellers is weak — studies show mice quickly get used to the sound, and the sound doesn’t penetrate walls or go around corners. Physical exclusion (sealing gaps) is far more reliable.

Will mothballs keep mice away?

No — and you shouldn’t try. Mothballs are registered pesticides, and using them as animal repellents is pesticide misuse. They release toxic fumes that are harmful to people and pets in enclosed spaces like garages.

How do I mouse-proof my garage door?

Replace the worn bottom rubber seal, add side and top weatherstripping, and install rodent guards on the bottom corners. Test at dusk: close the door, turn on the garage lights, and look for light leaking out from outside.

Should I seal entry points before or after trapping?

Trap first, seal second. If you seal every exit while mice are still inside, you trap them in the garage with no way out — and they’ll chew new holes, often into your house.

Related Guides

• How to Get Rid of Mice in Walls: Signs, Traps & Prevention
• Is Pest Control Safe for Pets? What Every Pet Owner Should Know
• Winter Pest Control Checklist: Keep Bugs and Mice Out — the winter pest control checklist.