How do Mice Get into the Attic? Why are They There?

Mice can infest just about any place in a home, but one of the most common places for them to nest is the attic. This can be troublesome for homeowners simply because they can cause so much damage and leave behind a massive, dangerous mess. Mouse feces can transmit disease and even make the very air in the attic unsafe to breathe.

If you have mice in your attic, you can’t afford to wait to get rid of them. In this guide, we’ll explain:

  • How and why mice get into the attic
  • Signs of mice in the attic
  • How to get rid of the mice in your home

How do Mice Get into the Attic? Why are They There?

Attics aren’t the most easily-accessible part of a home, so how do mice get there in the first place?

What you may not know is that mice can actually compress their bodies. This allows them to squeeze through the tiniest of spaces. In fact, mice can fit through a space no bigger than an inch.

Because they can compress their bodies, mice can fit through just about any crack, hole or space around the perimeter of your home, and make their way into the attic. They may have also gotten into your attic from your roofline or after jumping down from tree branches.

But why, of all places, would a mouse want to hang out in the attic of your home?

For one thing, your attic may just be the most convenient place if it was the first place they found. And because most people don’t spend much time in the attic, mice can go about their business uninterrupted for quite a while.

Signs of Mice in the Attic

How can you tell if there are mice in your home’s attic? There are so many places for them to hide, and they can build a nest in a place that’s difficult or impossible to reach.

One of the first things you’ll notice is noise. The noise may not necessarily come from the attic itself. You may actually hear scratching or squeaking in the walls.

Keep in mind that mice are nocturnal creatures, so they’ll be most active at night when you’re more likely to hear them. They may come down from the attic and run in between the walls to access areas of the home where they’ll find food and water.

You might hear:

  • Bumping
  • Scraping
  • Scratching
  • Thumping
  • Scrambling
  • Squeaking

If the mouse finds a path that doesn’t go by your bedroom, you may never actually hear them.

If noise isn’t giving them away, their droppings will. The presence of droppings is the first tell-tale sign that you have mice in your home. Mice will actually chew holes through the wall to access your kitchen drawers and cabinets from the back. If you have rodents in your kitchen, you should find droppings in different areas of the kitchen. You’ll also find droppings in the attic where they’re nesting.

Mice also pass urine as they travel, creating a trail that allows other rodents to find the food sources they’ve found.

A nest is an obvious sign of mice, but finding one in the attic can be challenge. Nests aren’t necessarily obvious either. They typically look like matted down material, and mice often build them in spots that are hard to get to. You should also find droppings near the nest.

Other signs of mice include:

  • Urine-stained areas
  • Chewed items, such as cardboard boxes, plastic or clothing
  • Mouse burrows (1” holes that run through the insulation)
  • Mouse hallways on the surface of the insulation (1” holes)

If you find any of the signs we’ve mentioned, there’s a good chance that you have mice in your attic.

Mice can cause some serious damage and pose a health hazard. They’ll chew through your insulation, leave their droppings all over your home and put your family at risk of contracting disease. It’s important to get rid of the mice as soon as you can to prevent damage and health risks.

5 Steps to Getting Rid of Mice in the Attic

You’ve found a mouse nest in your attic. Now what? How do you get rid of the rodents and keep them from coming back?

1. Identify and Seal Their Entry Points

Before you lay down any traps, you need to figure out how the mice are getting in. Remember – mice can compress their bodies, so they can fit through really small spaces. It may be tricky to find their entry points, but it’s worth the effort.

Start by checking the exterior lower level of your home. In most cases, mice get in from the outside and climb their way up to the attic. A mouse might climb into the attic through:

  • Cracks of gaps in your home’s foundation
  • Loose siding
  • Outdoor water taps
  • Gaps around doors or windows
  • Openings near utilities, water pipes and dryer vents

Once you’ve found the mice’s entry points, it’s important to seal all cracks, gaps and holes that are larger than 1/4.”

What’s the best way to seal holes?

  • Use steel wool or caulk for small holes
  • Use sheet metal, concrete mortar or heavy-gauge hardware cloth to fill larger openings
  • Make sure that windows, screens and doors fit tightly
  • Apply weatherproofing strips around doors that are loose

Don’t use plastic or wood products to seal holes or gaps. Mice will only chew on these materials and move right back into your attic.

2. Mouse-Proof Your Food Storage

The mice in your home want food. Once they’ve found it, they’ll stick around until you force them out. Even then, they’ll try to get back in because they know that your home is an easy source of food.

It’s easier than you think for mice to get into your food. They can easily chew through cardboard, paper and plastic. Yes, mice can chew through some plastic food storage containers, especially if they’re thin containers.

Store dried foods and snacks in glass or metal containers. You can also find mouse-proof plastic food containers of all sizes. Large containers are ideal for storing pet food and bulk grains.  

3. Lay Traps

Traps are the most effective way to get rid of mice. Yes, repellents can be effective, but if you already have mice in your house, you need to evict them first before trying to use deterrents.

You can also use poison, but then you have to worry about children or pets coming into contact with the substance. The other problem with using mouse poison is that you’ll have dead mice hiding in your home. If a mouse dies in a wall, it will be hard to access and the smell will be overwhelming.

Traps are the best option. Use either a snap or live trap to catch the mice. Snap traps are fatal, but live traps are not. There are other non-lethal traps as well.

You’ll need bait to attract and trap the rodents. Contrary to popular belief, cheese is not a good option for bait. It goes rancid too quickly.

Better bait options include:

  • Chocolate
  • Bacon
  • Peanut butter

It’s important to lay traps where there is known mouse activity in the attic, such as:

  • Entry points
  • Where you’ve found droppings
  • Near the nest

Laying traps is the first step, and it’s important to check them often (especially if you’re using a non-lethal one). The last thing you want is for the mouse to dehydrate or starve to death before you have the chance to release it. You also don’t want to leave a dead mouse in a snap trap for too long.

If you’re using non-lethal traps, make sure that you follow the directions properly.

It may take a few days to catch a mouse in a trap. If you find that no mice are being trapped, try moving the traps to different spots in the attic.

4. Release or Dispose of the Mice

As mentioned earlier, it’s important to check on your traps regularly.

If you’re using a non-lethal trap, you’ll want to release the mouse into the wild. Be sure to release them far away from your home, or they will return to your home. Find somewhere that’s several miles from your home and not on private property.

5. Clean-Up

If you’ve used a lethal trap, such as a glue trap or snap trap, you’ll need to clean up the dead mice before they start decaying. You’ll also need to clean up the droppings and destroy the nest. But it’s important to stay safe when cleaning up. Otherwise, you’ll expose yourself or your family to potentially serious disease.

Wait until there is no more evidence of a mouse infestation before getting ready to clean. Wait about five days, and be sure to cross-ventilate the area for at least 30 minutes by opening doors and windows. The fresh air will help remove potentially contaminated air from the area. Be sure to leave the area during the airing-out period.

The U.S. Centers for Disease Control and Prevention (CDC) provides tips and advice on how to safely clean up after rodents.

You’ll want to make sure that you’re fully covered (long pants, long sleeves, etc.), and that you wear latex gloves throughout the entire clean-up process.

Cleaning Up Urine and Droppings

Before you start cleaning, it’s important to be careful not to stir up dust. Do not sweep or vacuum droppings, nesting materials or urine.

While wearing latex gloves, spray the droppings and urine with a disinfectant, or a mixture of bleach and water (1 part bleach to 9 parts water). If you’re using a commercial disinfectant, make sure that you follow the directions properly. Allow the solution to soak for five minutes. This will inactivate any virus that may be hiding in the droppings or urine.

Use a paper towel to pick up the droppings and urine. Dispose of the waste in the garbage. Once you’ve disposed of the urine and droppings, disinfect the area again using a commercial disinfectant or bleach and water.

Cleaning the Attic

Depending on the type of attic, you may or may not be able to clean and disinfect the flooring. If so, use either a bleach and water solution or a commercial disinfectant.

If mice have gotten into exposed insulation, you’ll need to carefully remove contaminated pieces and place them in plastic bags for removal.

If you have potentially contaminated materials in storage bins or boxes, carefully remove the storage vessels and place them outdoors in a well-ventilated area that receives direct sunlight. You may be able to disinfect the storage containers using a disinfectant or bleach and water.

Any contaminated items inside of storage boxes or containers should be removed while outdoors in the ventilated, sunlit area. The CDC recommends staying upwind to avoid having any dust or debris being blown in your face. You may be able to decontaminate some of the items, but it’s best to discard any items that you really don’t need anymore.

Dispose of all cardboard boxes that have been contaminated with urine or droppings. Glass, plastic and metal containers can all be disinfected with either commercial disinfectant or a bleach and water solution.

When you’re done cleaning the area, make sure that you decontaminate your gloves, and wash your hands well with soap and warm water.

Removing Dead Rodents and/or Nests

When removing a mouse nest or dead rodents, it’s important to wear gloves and, if possible, a respirator.

Here’s what the CDC recommends when disposing of dead rodents and nests:

  • Spray the dead rodent, nest and the surrounding area with a disinfectant or a bleach and water solution.
  • Allow everything to soak for five minutes to deactivate any virus that may be in the droppings or on the dead mouse.
  • Place nesting materials and/or dead mice in sealed plastic bags. Place the bags in a second plastic bag, and seal again.
  • Place the bags in a covered trash can for disposal.

6. Adopt a Cat

If you want to avoid having to trap and clean up after mice, your best bet may be to adopt a cat. Cats are natural predators of mice. They will catch and dispose of the mice for you. They’re also a natural deterrent. If you have a cat in your house, you can be sure that the mice nearby will know about it and won’t want to take any chances.

Mice are sneaky little pests, and they can easily build a nest in your attic without you even knowing about it until it’s too late. Use our tips above to trap mice, clean up after them and keep them from coming back in the future.

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