How to Keep Mice Out of Your Attic

Attics are warm, dry, out-of-the-way places perfect for storing seasonal items, home decor, family keepsakes, and just about anything else you want out of sight and out of mind. It's for that very reason, however, that they're ideal for something else: a mouse invasion. So, how to get rid of mice in the attic? It starts with remembering this space exists.

Unlike a garage that gets used every day, your attic is likely to be the one place in your home where you stash things and forget about them. And all that stuff? Well, with no people or pets around, it's just fodder for nest-making, as far as mice are concerned.

Once mice are living undisturbed in your attic, they can easily move into walls, wreaking havoc and spreading disease-carrying germs while you remain oblivious to their goings on—until it's too late. Because this situation can escalate quickly, here's what you need to know about how to get rid of mice in the attic, as well as what to do to keep them from coming back.

How to Tell if There Are Mice in Your Attic

It can be tempting to go on high alert over noises in the house coming from above. After all, there's nothing up there except some boxes of stuff, right? Don't assume you have a rodent problem on noise alone; use these tips to help determine what's going on up there.

• You spot droppings in other rooms. If you discover mouse poop in high-traffic areas of your home, it's worth making a trip to the attic to see if they're hiding out up there. Though mice nest in quiet, cozy places, they'll travel through walls and ceiling voids to find fresh food—as far as 50 feet from their safe haven. If you're lucky enough to have never discovered them before, mouse droppings look like dark-colored grains of rice. If you spot some, wear gloves when cleaning up: rodent poop contains bacteria and viruses. For more info on how to dispose of them safely, read our article, How To Handle Mouse Droppings.
• You hear nighttime noises. Faint sounds from the attic, as well as in walls and ceilings, can come from nocturnal mice as they scurry between their nests and food sources. Listen for subtle sounds like clawing, squeaking, gnawing, and running.
• You smell an unpleasant odor. Mice themselves have a strong, musky scent, especially when there's a good number of them living in close quarters. They pee a lot, too, which can leave an attic smelling uniquely pungent.
• You have electrical shortages or outages. Mice have been known to chew through cables, electrical wiring, wood, and other construction materials. Intermittent or non-working appliances and lights could indicate an infestation.
• You notice smudges along baseboards. Mice travel the same path between their nest and any food they're foraging night after night, leaving behind oily streaks and smudges from where their fur touches walls and baseboards.

How to Protect Your Stuff From Mice in the Attic

Attics can easily become a dumping ground for a wide assortment of goods. Some of these items are fine for storing in a dry, well-ventilated attic as long as they are protected from mice. Other things, not so much. Some of the objects in your attic might even be attracting mice to it!

Here's a list of common attic items and how to handle them.

• Holiday decorations: Jars of candy, strings of popcorn, and any other decorative edibles need to be tossed out once the holidays are over. Place the rest of your decorations in clear plastic bins with lids that fasten shut.
• Furniture: Mice like to gnaw on wood and plastic furniture as a way of sharpening their teeth. They also make nests in upholstery, so sofas with metal legs aren't safe, either. If you plan to keep furniture for a prolonged amount of time, move it to a storage unit.
• Family keepsakes: Pay extra attention when storing keepsakes or other personal items, like handcrafted art projects made from things like dried-pasta. Mice can mistake them for food—plus, a hot attic can ruin these invaluable items. Find a cooler, safer spot to store them.
• Housewares: Saving dishes, pots, and pans for your kid's first apartment? These objects are attic-friendly but don't store them in cardboard boxes. Mice may chew up boxes and use the shreds to make a nest.
• Linens and clothing: Go ahead and store these things in the attic as long as the materials can take the heat and you safely tuck them away in heavy-duty bins with well-fitting lids.
• Luggage: Soft-sided suitcases, duffels, and backpacks are at risk of being chewed on by mice. Storing luggage inside a heavy-duty container may sound counterintuitive, but you'll be better off for it.
• Toys: Though it's unlikely mice will gnaw on toys since they aren't useful for food or shelter, it's a good idea to store teddy bears and other plushies in closed containers.
• House décor: Metal, glass, and ceramic items are fine to store on open shelves or in plastic bins, just not in cardboard boxes. Things like wreaths, silk flowers, or extra pillows are potential nesting materials and should be stored in tightly-sealed containers.
• Insulation: While not a storage item, most attics have some kind of insulation to be mindful of, because mice will shred it if given the chance. Talk to a professional about how to seal it off permanently.

Get Rid of Mice in the Attic

Whether you already suspected a problem or were unpleasantly surprised by an infestation, if mice are in your attic, they need to go. Follow these steps to get rid of mice and keep them from coming back.

1. Block Entryways

You might think baiting and get rid of mice should come first, but it actually works better if you fortify the attic and contain the infestation before going after any rodents. Block entry and exit points by looking for light coming through cracks, crevices, and gaps. These can include areas in and around your roof and the exterior of your homes, such as gutters, vinyl siding, and vents. Close the damper on your fireplace when you're not using it, and add a chimney cap for another layer of protection.

Mice can enter narrow holes as small as ¼ to ½ inch in diameter (about the size of a dime). Depending on the area or the material you're plugging, fill it with an appropriate mouse-resistant material, such as expandable foam, cement, mortar, galvanized sheet metal, hardware cloth, wire mesh, or steel wool. A combination of these chew-proof materials, like hardware cloth or steel wool mixed with caulking or expandable foam, works best for plugging odd-shaped holes.

2. Control the Infestation

The attic can be a difficult place to reach, making it harder to deal with problematic mice. Here are some common mistakes to watch out for—and what to do instead—to get rid of mice in the attic.

• Put mouse bait in the right place. Since attics can be awkward in shape, size, and location, it's understandable that placing bait stations here can be a little different than anywhere else in the house. Still, be careful not to place bait stations willy-nilly. Put them where mice travel most frequently, such as along rafters and next to items stored in the attic, as far as you can reach.
• Use enough stations for the job. Unfortunately, when it comes to getting rid of mice in the attic, one-and-done might not do it. Increase your chances of a mouse finding a station—meaning, a higher success rate—by using more than one station placed at intervals of 8 to 12 feet apart. The Tomcat® Mouse Killer Child Resistant, Refillable Station gives mice easy access to bait, plus you can use it again (after cleaning it thoroughly), giving you plenty of coverage with just a few stations.

Keep adding fresh bait. When trying to get rid of mice in the attic, it can be disheartening to not see progress right away. Have patience and stick with it: the payoff is worth it. One daily task is to keep an uninterrupted supply of fresh bait flowing. Mice just like it better. Do this for at least 15 days, or until there aren't any signs of mouse activity. Use the Tomcat® Mouse Killer Refillable Bait Station - Advanced Formula to keep the coverage steady: The advanced formula is even more palatable to mice* and each station comes with 12 bait blocks (and each block can can kill up to 12 mice).

• Use a repellent. It's tempting to stop trying to get rid of mice in the attic once the baiting is done. That's not a good idea, unless you want a repeat occurrence. To keep mice from coming back, deter them with a smell and taste they hate, such as peppermint or ammonia. Tomcat® Repellents Rodent Repellent Continuous Spray has an essential oil formula that's proven to prevent entry, nesting, and foraging.

3. Remove Gateways

Since mice are notorious climbers and jumpers, you'll want to remove any extra opportunities for them to get in your attic. That means trimming tree branches and pruning bushes around the perimeter of your house; two feet from the exterior is a good distance. Move or store lumber, firewood, trash cans, junk piles, and other potential "ladders" several feet away from your home, too. Keep in mind that mice can grab onto brick and siding and climb their way up and onto the roof of your home, though so continue to monitor your attic with the change of every season.

There you have it. That's what you need to know about how to get rid of mice in the attic. If you keep these tips in mind you'll be well on your way to having—and maintaining—an attic that's as mouse-proof as possible, so you can go back to storing and ignoring whatever you put in this functional space.