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How Do Mice Get In the House?

February 28, 2021
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Every year during winter, around 21 million American households report rodent infestations. These rodents are difficult to exterminate without the help of pest management professionals, which is why it’s better to stop them from entering the house in the first place.

So how do mice get inside the house? These pesky rodents utilize any opening they find to get into different buildings. Some of their common entry points are through open garage doors, window and wall cracks, chimneys, sewer lines, crawl spaces and basements, vents and air ducts, gutters, foundation cracks, and holiday decorations.

9 Common Ways Mice Enter the House

Mice enter homes in search of shelter, food, and water. Although they’re small in size, these rodents are a huge headache for many homeowners. Mice steal food from the kitchen, damage the house’s structure, and contaminate anything they touch. One of the best ways to stop a mice infestation from occurring in the first place is to prevent mice from entering the house.

Mice don’t get inside homes by knocking on the front door. These pests utilize every vulnerable opening in the house to enter. While there are natural ways to keep them out of the house, such as adopting pets who are good at hunting mice, sealing the rodents’ possible entry points are still the better solution.

Keep an eye out for these nine areas that are common entry points for mice:

1. Open Garage Doors

Mice are attracted to garages because of the shelter, warmth, food, and clutter. Most homeowners store their bird seed and pet food in garages, which makes the place all the more attractive for mice. Garages are also a goldmine for mice who are looking for nesting materials, such as cardboard, cotton, leaves, and other material.

They’re usually the first place that mice visit before entering the house and building a nest there. If the garage is left unchecked for months, the infestation becomes a more serious matter that only a pest management professional can handle.

Always remember to close the garage door when it’s not used. Here are four other fixes to ensure that the garage is secure from mice entry:

  1. Install rubber sweeps or weather stripping on the garage door.
  2. Fix or replace the garage door threshold.
  3. Repair the damages on the garage door.
  4. Seal any access holes for air vents, plumbing pipes, and air conditioner hose connections.

2. Wall and Window Cracks

Mice are small enough to squeeze through gaps and holes that are just the size of a dime. They take advantage of any cracks on the wall or near windows. Old buildings are especially vulnerable to mice entry because more wall cracks develop due to aging.

Windows frames exist to seal the space between walls and glasses, but they’re imperfectly installed most of the time. They leave small gaps in the corners that mice use to enter the house. Typical home sealants may not be enough to keep rodents out because their strong teeth easily chew through different materials.

Steel wool is an effective home remedy to prevent mice and other rodents from getting through wall and window cracks. The hole is typically plugged with steel wool and sealed with caulk. Even with their strong teeth and jaw, rodents find it difficult to chew through steel wool.

3. Chimneys

Many birds and animals get inside the chimney for different reasons. Some of them might be trapped, but others are there because chimneys are a good nesting place or entry point. Watch out for occasional scratching and squeaking noises, as well as other signs of rodent activity on the chimney.

To prevent mice from entering the house through the chimney, here are a few precautions to follow:

  1. Clean the chimney regularly.
  2. Keep the damper closed.
  3. Install a mesh-covered chimney cap.
  4. Seal all cracks and crevices on the chimney pipes and soffit vents.

4. Sewer Lines

Rodents like rats and mice love the sewer. The place provides the best conditions for these filthy rodents to thrive. It’s where washed down food from the sink and flushed excrements with half-digested nutrients from the toilets are found.

As scary and gross as it sounds, mice can learn to enter the house through the toilet and sewer lines. They’re excellent swimmers and climbers that easily fit through tight spaces. Here are some tips to keep these rodents out of the house:

  1. Always close the toilet lid.
  2. Cover the drains with tight-fitting screens grates or screens.
  3. Replace leaky pipes and repair all sewer lines.

5. Crawl Spaces and Basements

Crawl spaces are structures similar to basements that allow outside air to circulate under the house. They can be around a few feet high or as big as a basement. They’re also a handy place to install HVAC units and pipes. But with the convenience that crawl spaces bring is the huge chance of mice infestations occurring in the house.

Rodents like mice find that crawl spaces are ideal places to live in – it’s a dark place where they stay hidden, but it’s also near holes they use to get in and out of the house. Mice in crawl spaces also attack the house’s water barrier, which leads to the formation of mold and fungi in the area. Mice-proof the house’s crawl spaces with these steps:

  1. Avoid leaving food that mice might eat in the crawl space.
  2. Install a light in the crawl space.
  3. Keep the crawl space dry.
  4. Seal any gaps or holes in the crawl space.

6. Vents and Air Ducts

Air ducts and vents are common pathways for mice. These rodents travel through the air ducts and vents because they want to hide from humans. These are also excellent places for mice to build a nest in.

The biggest problem with mice staying in vents and air ducts is that they cause structural hazards. These rodents chew through everything to collect nesting materials or trim their continuously growing teeth. Protect the house’s vents and air ducts with these tips:

  1. Get the ducts professionally sealed.
  2. Install vent and flue covers.
  3. Repair damages that were previously caused by other rodents.

7. Gutters

Mice have paws that grasp almost any kind of surface. This allows them to climb the gutters and other roof openings to get inside the house. Gutters are also a great place for mice to gather twigs, leaves, and other nesting materials. However, removing the gutters and downspouts in a home isn’t a viable option because they’re a place for excess rainwater and melted snow.

The best way to ensure that mice won’t climb the gutter in the house is to keep it well-maintained. Several companies offer gutter cleaning and repair services if you’re too busy to do it. Gutter spikes and gutter guards are effective in preventing mice from climbing and staying in the gutter without interrupting the water flow.

8. Foundation Cracks

In addition to being excellent climbers and swimmers, mice are also great at burrowing. These rodents dig under manmade structures to build nests or hide from humans and other predators. Since they burrow the ground near the house, it’s highly likely that these rodents eventually find their way inside the house once they spot a crack in the foundation.

These rodents also cause the foundation to weaken directly and indirectly. Their constant burrowing habit negatively affects the concrete’s stability. Some of them also chew through the construction material.

To keep these pesky rodents out of the house, make sure to frequently check the yard for signs of burrowing. It’s also crucial to repair any cracks in the house’s foundation before they become bigger; remember that mice only need a hole in the size of a dime to invade a house.

9. Along with Holiday Decorations

When the holidays roll around, many people design their houses to look festive. It’s time to open cabinets and boxes upon boxes of holiday decorations from the unused shed in the yard. But this time is also the perfect opportunity for mice to move from the shed into the house.

Holiday decorations stay unused in cabinets and storage rooms for months, which is why mice tend to burrow in them. Before moving these boxes of decors into the house, carefully inspect them first for signs of mice nest or activity.

How Do Mice Entry Points Look Like?

In the cartoons, mouse holes are nicely cut semi-circle entrances along the baseboards of the walls. But in reality, mouse holes aren’t easy to find because they might look like any of the following:

  1. Damage wall section
  2. Gap between building materials
  3. Space between mortar
  4. Crack in the foundation

Mice easily squeeze through the smallest crawl spaces and holes as small as a dime. And even if you managed to find these holes, they don’t automatically lead to mice nests. They only serve as a door or a pathway for the pesky rodents to get in and out of the house.

Blocking mice entry points is a good preventative measure to keep the rodents out of the house. But if they already managed to get inside, it’s better to eliminate them completely first before sealing all possible entrances around the house.

Rodent control devices like traps and bait stations are effective for catching mice. Make sure to plug the holes with caulk and steel wool so that the rodents will have a hard time chewing through the material and returning to the house.

Keep Your Home Rodent-Free with Positive Pest Management

Finding the mice entry points around the house is only the first step in keeping it rodent-free. If you suspect a mice infestation at home, call Positive Pest Management to eliminate the filthy rodents quickly and effectively.

Here at Positive Pest Management, our professional staff is experienced in handling any rodent extermination situation. We utilize IPM-based practices to ensure that the family and the environment is safe as we get rid of rodents on the property.

Learn more: Best Bait for Mouse Trap