If you searched "how to keep mice out of garage," you have probably already found the signs: droppings behind the recycling bin, a chewed bag of bird seed, or shredded cardboard in a corner. A garage is rarely where the problem ends. It sits between the outdoors, your car, and your house, so mice that settle there have easy access to all three.
This guide treats the garage as what it is for mice in winter, a transit hub, and walks through how to cut off each route: in from outside, into the car, and on into the house.
The Short Answer
Seal the gaps around the garage door and walls, remove food and nesting material, and close off the routes from the garage into your car and your house. Trap any mice already inside, clean up safely, and check monthly through winter. A scent repellent can add a layer in corners and near entry points, but sealing and cleanup do most of the work.
Why the Garage Is a Transit Hub for Mice
According to the National Pest Management Association (NPMA), deer mice seek shelter in garages during winter, and parked cars add warmth and plenty of chewable material. The University of California Integrated Pest Management Program (UC IPM) notes that house mice often enter homes in autumn as nights get colder, and lists garages among the places to look for nests.
A garage often holds bird seed, pet food, cardboard, and quiet corners. Once mice are inside, the next step is short. Your car is a few feet away, and the house is on the other side of one door and a shared wall.
Mice in Garage: Signs to Look For
- Small, dark droppings along walls, on shelves, and behind stored items
- Chewed bags of seed or pet food, and gnawed cardboard
- Nests of shredded paper or fibrous material in boxes or wall voids
- Nesting material or droppings under the hood or in the trunk of a parked car
How to Keep Mice Out of Garage Spaces: Step by Step
Step 1: Check the Garage Door
The big door is the most obvious way in. According to the CDC, mice can fit through a hole the width of a pencil, about 1/4 inch. With the door closed, look along the bottom seal, especially at the corners where it meets the side weather stripping. If you can see daylight from inside, that gap needs fixing. UC IPM recommends that doors fit tightly and notes that rubber and vinyl are gnawable, so a worn or chewed seal needs replacing, and door edges may need metal to resist gnawing.
Step 2: Seal the Walls, Pipes, and Vents
The CDC specifically advises sealing garages and outbuildings, not only the house. Check where the wall meets the foundation, and around every pipe, wire, cable, and vent that passes through a garage wall. The CDC recommends steel wool held in place with caulk or spray foam for small holes, and hardware cloth, metal sheeting, or cement for larger ones. Our guide to using steel wool for mice covers this step in detail.
Step 3: Close the Route Into the House
This is the step most people skip. Check the door between the garage and the house: it should fit tightly, with weather stripping and a door sweep at the bottom. The NPMA recommends door sweeps and weather stripping on doors. Then check the shared wall from the garage side, especially around water heater and furnace pipes, dryer vents, and any spot where utility lines pass into the house. The CDC lists all of these as places to inspect.
Step 4: Remove Food and Nesting Material
The NPMA advises against storing pet food or bird seed in garages or sheds. If you must keep them there, the CDC recommends sealed plastic or metal containers for grain and animal feed, and trash cans with tight lids. The NPMA also suggests swapping cardboard boxes for resealable plastic containers, keeping items off the floor, and sweeping up crumbs regularly.
Step 5: Protect the Car
Park away from stored seed and trash, keep the cabin free of food wrappers, and look under the hood regularly in winter. Our guide on how to keep mice out of your car engine has the full checklist.
Step 6: Trap the Mice Already Inside
UC IPM calls trapping the preferred method in homes, garages, and other structures where only a few mice are present. The CDC recommends snap traps and advises against glue traps and live traps. Place traps along walls, out of reach of children and pets.
How to Get Rid of Mice in Garage Spaces, and Clean Up Safely
Seal first, then trap, then clean. For cleanup, the CDC recommends wearing rubber or plastic gloves, never sweeping or vacuuming droppings or nests, and soaking them with a bleach solution (1.5 cups of household bleach per gallon of water) or a disinfectant for 5 minutes before wiping up with paper towels. If you find nesting material in your car's air intake, the CDC says to remove both the nest and the air filter, and to consult a mechanic if anything looks damaged.
A quick note on ultrasonic plug-ins, which are often sold for garages: UC IPM says ultrasonic sound has very limited use in rodent control because it is directional, does not penetrate behind objects, and loses intensity with distance.
When to Call a Professional
Call a licensed pest control professional if you find signs in the house as well as the garage, if activity continues after you have sealed and trapped, or if you see chewed wiring in the garage or the car.
Cheat Sheet
- A garage connects mice to the outdoors, your car, and your house. Block all three routes.
- Check the garage door corners for daylight. Replace chewed or worn seals.
- Seal gaps of 1/4 inch or more around pipes, wires, and vents with steel wool plus caulk, or metal.
- Give the house door a tight fit, weather stripping, and a sweep.
- Move seed and pet food into sealed metal or heavy plastic containers, or out of the garage.
- Replace cardboard boxes with lidded plastic bins, off the floor.
- Snap traps along walls, out of reach of kids and pets. Never vacuum droppings.
Where BioGuard Fits
We sell BioGuard Natural Rodent Repellent, a pack of 12 scent balls infused with peppermint and cinnamon essential oils. The garage is one of the places it is made for: in corners, near the door seal, along the shared wall, and around a parked car. It is a repellent, not a removal product, so use it after sealing and cleanup, not instead of them. Replace it every 4 to 6 weeks, keep it away from children, pets, and food, and expect results to vary.
Frequently Asked Questions
Why do I have mice in my garage?
Garages offer shelter from the cold, stored food like bird seed and pet food, and cardboard for nesting. A small gap under the garage door or around a pipe is often enough to let them in.
Can mice get from the garage into the house?
Yes. A loose door between the garage and the house, or gaps around pipes and vents in the shared wall, can give them a route inside.
Will a garage door seal keep mice out?
A tight seal helps a lot, but only if the corners close fully and the seal is not chewed. Rubber and vinyl are gnawable, so inspect the seal each fall.
What smell keeps mice out of a garage?
Peppermint and cinnamon are common scents in repellents, but no smell works on its own. Read our honest guide to whether peppermint oil keeps mice away.