How Mice Get in the House Without You Noticing

If you’re currently facing a mouse problem, you may be wondering how they got into the house. Mice are tiny, agile creatures that are good at climbing and sneaking their way through the smallest openings. An adult mouse can squeeze through gaps only one quarter of an inch wide. They’re so quiet that mice often come as a surprise.

While it may seem nearly impossible, know that you can keep mice out with a little pest-proofing. There are a few common entry points that you can fix yourself. Look for these openings below.

Door Gaps

Believe it or not, one of the most common ways that mice get into the home is by crawling under the door. If you can fit a pencil pen under the door, you can fit a mouse. Doors that have been left open in the evening may also invite mice into the home.

Invest in a screen door so you can let the air in and seal the gaps underneath your doors by adding some weatherstripping. You can find weatherstripping at the hardware store and install it yourself for just a few bucks.

Wall Vents

Mice can climb walls, then chew their way through plastic wall vents and into the walls of the home. While these are necessary for exhaust and ventilation, you can cover them to keep rodents out. Find some quarter inch, 16-gauge, galvanized steel mesh from the hardware store, then cut it to create a cap you can screw over the vent. If you can’t find the right materials, contact a local pest removal company.

This same logic goes for roof vents, too. Mice can climb onto the roof and slip inside them. Squirrel often chew their way through plastic roof vents and raccoons can tear them off with their paws. Cover them with the same mesh to keep wildlife out of the attic.

Window Frames and Screens

Window frames may crack with time, creating drafts and openings that let in mice. Take a look at your window frames and seal any cracks you find with silicone caulking. Be sure to secure the bottoms of your bay windows. Then, check your window screens and make sure that they are well fit. If they’re torn, you can patch them up or replace them entirely with new screens from the hardware store.

Utility Lines (plumbing and electrical)

The cables that run into the home are often surrounded with a gap that leads mice into the wall. Check your air conditioning unit, your garden hose, and other cables for gaps, then seal them off with expanding foam or caulking. Wider spaces can be stuffed with steel wool.


Damaged soffits and gaps between the soffits and the outer walls of the home are common entry points. Mice can climb up the walls, then crawl through the gaps and into the attic. From there, they may migrate into the kitchen and the rest of the home.

You can block out the gaps along your soffits with caulking. Wider gaps can be covered with mesh to ensure that no animals chew their way through.

How to Get Rid of Mice

The key to getting rid of mice is to find their points of entry and block them out. If you don’t exclude the home, you risk having more mice come, spoiling your attempt at extermination. Address every point of entry you found, then do the following.

Remove Food and Water Sources

Mice are attracted to homes where they can find food and places to hide. Before you set any traps, clean the home from top to bottom. Vacuum, mop, and clean every surface. Pull out your large appliances and clean the floors beneath them. Empty out the pantry, too, and get rid of every crumb. Store food in glass jars and impenetrable containers. Removing every piece of food like this will force mice into baited traps.

While cleaning, get rid of the things you don’t need and reduce clutter. Put things away properly to create space and get rid of hiding spots. Move things off the floor. Mice like to hide in wall voids, drawers, appliances, and other quiet, enclosed parts of the house. They move around in sheltered areas. Tidying up may help you find these nesting spots and bring mice out into the open.

Set Lots of Traps

Choose between snap traps, electronic traps, or live traps, then bait them with a very small amount of food. The more traps you set, the better. Wear a pair of gloves while you handle your traps to ensure that you do not leave your scent on them. Set them along the walls of infested rooms and in the backs of your kitchen cabinets.

Check your traps every day. If you are using traditional snap traps, spray any dead mice you catch with disinfectant before handling them. Wait for the disinfectant to work – about 10 minutes – then throw the animal out in a sealed plastic bag. Disinfect the trap, then reset it. Many electronic traps and live traps are contactless so that you do not need to handle the animals closely.

Call an Exterminator

The most reliable way you can get rid of mice is to hire a licensed exterminator. He or she will perform an inspection that finds every potential entry point, then get rid of the problem quickly with rodenticide. Rodenticide for mice comes in little plastic boxes that only mice will crawl into. After a few ingestions, they retreat into their nests and perish.

Not only will the technician get rid of the mice for you but offer pest-proofing, too. The technician can seal and block off every entry point so that no mice come back.

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