Mice in the garage in winter: what to do
Once Ottawa nights turn cold, the garage is often the first place mice move into. It is sheltered, out of the wind, and usually full of things they can eat or nest in. Here is how to tell if you have mice in the garage, how to get rid of them, and how to stop them reaching the house.
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Why do mice move into garages in winter?
Mice look for shelter as the temperature drops, and a garage is warmer and drier than outside. Most garages also have food and nesting material close at hand: birdseed, grass seed, pet food, recycling, and stacks of cardboard boxes.
The way in is usually the bottom seal of the garage door. It wears out at the corners first, and a mouse only needs a gap about the width of a pencil. Other common entry points are gaps around the side door, cracks where the garage slab meets the foundation, and holes where cables, gas lines and outdoor taps pass through the wall.
Attached garages are common in suburbs like Kanata, Barrhaven, Stittsville and Orléans, and they share a wall with the house. Newer subdivisions next to fields, construction sites and the greenbelt can see mice moving in as the land around them changes.
Signs of mice in your garage
You will usually find the clues before you see a mouse. Look for:
- Small, dark, rice-shaped droppings along walls, on shelves, under workbenches and around stored items.
- Chewed bags of birdseed, grass seed, dog food or anything stored in paper or thin plastic.
- Nests of shredded cardboard, paper, fabric or insulation in quiet corners, boxes or stored furniture.
- Small tracks in the dust on the floor, or in the snow near the corners of the garage door.
- Nesting material or droppings in stored lawn mowers, snow blowers, barbecues and patio cushions.
- Gnaw marks on wood, plastic bins or the rubber seal at the bottom of the garage door.
- A musty smell in closed cupboards or boxes.
For a wider look at what mice leave behind around the home, see our guide to the signs of mice in your house.
Can mice get into the house from the garage?
Yes. An attached garage is one of the most common routes into the house. Mice follow the shared wall and get in through gaps around the door from the garage to the house, holes where pipes, wires and the dryer vent pass through, and the gap at the top of the foundation wall.
If you are finding signs in the garage, check the basement, laundry room, mudroom and any room next to the garage as well. Scratching in the wall next to the garage at night is a common sign that mice have already made it inside. Our guide to scratching in the walls at night explains how to tell mice from other noises.
Check your car too
Mice sometimes nest in parked cars over the winter, under the hood, in the engine bay, or in the air intake and cabin air filter. A car that sits in a warm garage for days at a time is an easy target.
Look under the hood for leaves, shredded material or droppings, and check the cabin air filter if you notice a musty smell when the fan runs. If you see chewed wires, or warning lights come on, have a mechanic check it before driving.
How to get rid of mice in the garage: what to do right now
These steps make the garage less attractive and help stop mice reaching the house:
- Move birdseed, grass seed and pet food into sealed metal or hard plastic bins.
- Get cardboard boxes off the floor and swap them for plastic tubs with lids.
- Keep garbage, recycling and green bins closed tight, and rinse them out.
- Clean up droppings safely: wear gloves, wet them with disinfectant first, then wipe them up. Do not sweep or vacuum them dry, because that spreads dust.
- Keep the garage door closed, and check the bottom seal from inside with the lights off. If you can see daylight at the corners, it needs replacing.
- Add or replace the weatherstripping and door sweep on the door between the garage and the house.
- Move firewood a few metres from the house and keep it off the ground.
- Note where you see signs. It helps the technician find the route mice are using.
What not to do
- Do not put out poison yourself, especially with children or pets in the home. Mice can carry it into walls and die out of reach, leaving a smell that can last for weeks.
- Do not plug holes with spray foam, caulk or newspaper alone. Mice chew through them.
- Do not seal up the house if mice are already inside. Sealing traps them in the walls, where they chew new holes.
- Do not leave a side or overhead door open for long periods on mild winter days. A warm, open garage invites mice in.
How to keep mice out of the garage for good
Treatment deals with the mice that are there now. Keeping new ones out is about closing the gaps. Our winter mouse-proofing checklist walks through the whole house from the outside in, and our guide on how mice get in and how to keep them out covers the most common entry points.
- Replace a worn garage-door bottom seal and add corner pieces where the seal meets the frame.
- Seal small gaps around pipes and cables with copper or steel mesh packed in tightly, then sealant over it.
- Cover larger openings with metal mesh or sheet metal, not foam or wood.
- Keep the garage floor clear so you can spot new droppings early.
For larger jobs, such as garage-door seals, door sweeps and gaps at the roofline or foundation, our rodent proofing service seals the gaps with materials mice cannot chew through. It is quoted after an inspection, with photos of each gap and a written price before any work starts.
Is it mice or rats in the garage?
Mice are by far the most common rodent in Ottawa garages in winter, but rats do turn up. Rat droppings are much larger, about the size of a raisin, and rats leave bigger gnaw holes and heavier runways along walls. Noises in the garage at night that sound like thumping rather than light scratching can also point to rats.
Our mouse and rat control covers both. Rats can need more bait stations and more follow-up, so if the job turns out bigger than a standard treatment, we confirm the price with you after the inspection.
Cleaning up after mice safely
Mouse droppings and nests can carry germs, and deer mice, which are common around fields and wooded edges outside the city core, can carry hantavirus. Public health agencies in Canada advise a few simple precautions when cleaning up:
- Open the garage door and air the space out for a while before you start, especially if it has been closed up.
- Wear rubber or disposable gloves, and a mask if you are cleaning a large amount.
- Wet droppings and nests with a household disinfectant or diluted bleach and let it soak before wiping them up.
- Bag everything, seal the bag and put it in the outside garbage.
- Wash your hands well afterwards. If anyone feels unwell after cleaning up after mice, see a doctor and mention the mice.
Quick answers about mice in the garage
- Will mice leave the garage on their own in spring? Some may, but a garage with food and nesting material is a year-round home, and mice breed quickly. Waiting usually means more mice, not fewer.
- Is one mouse a problem? One mouse you see often means others you do not. If you find droppings in more than one spot, plan on more than one mouse.
- Are bait stations safe in a garage with kids and pets? We use tamper-resistant, locked stations placed where children and pets cannot reach them, and we tell you where every station is.
- Do I need to leave the house? No. You can stay home during the visit.
- How long until the mice are gone? The bait works over several days, so most homes see activity drop within a week or two. Sealing the entry points is what keeps them from coming back.
When to call a mouse exterminator
Book a technician if you find droppings in the house as well as the garage, hear scratching in the walls next to the garage, find chewed wiring, or the signs come back after you have cleaned up and sealed what you can. Those usually mean more than one or two mice, and an entry point you cannot see.
How much does mouse control cost in Ottawa?
Our mouse and rat control is one flat price of $299 plus HST for houses, townhomes and condos, including the follow-up visit. Rodent proofing is quoted separately after an inspection. You can see every price on our pricing page.
Book mouse control online
Pick a day and time window on our booking page and we will email you to confirm. Mouse and rat control includes a full inspection of the garage, basement, attic access and exterior, locked bait stations placed away from children and pets (we do not use snap traps or glue traps), small gaps sealed with steel mesh on the first visit, a photo report of the entry points we find, a follow-up visit, and a six-month guarantee: if mice come back, we re-treat for free. You do not need to leave the house during the visit.
Not sure yet? Read our pest control FAQ or contact us.
Book online See mouse & rat control ($299 + HST)
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General information for homeowners. Every home is different; your technician will confirm what applies to yours.
Let's make them gone.