How to Seal a House From Mice

Any home can experience a rodent infestation, especially in the fall and winter when mice are looking for shelter and food. You may think your home is rodent-proof, but mice can squeeze through a hole that is only 1/4 inch wide, which is why it’s vital to learn how to seal your home from mice. 

If you spot tiny black droppings, nests, gnawed-on cereal boxes, or suspicious holes in your baseboards or cabinets, you likely need to take steps to protect your home against little Mickeys and Minnies. Luckily, our guide will show you how to safely, humanely, and cost-effectively seal your house from mice. 

1. Fix Gaps Around Your Home

Sealing gaps with rigid materials that mice cannot chew through is vital. Mice notoriously chew through wood and plastic vent covers and ducts. Instead, you should use the following materials to seal gaps:

1. Use steel wool to stuff mice holes.

2. Add bricks to your home’s siding or foundation to keep mice out.

3. Use caulk to seal any gaps or cracks in walls and doors.

4. Use hard-wired metal screens—lath metal and hardware cloth.

5. Cut larger metals to fit large holes in metal sheeting and roof flashing.

2. Inspect and Cover Fans and Vents

An exhaust fan or dryer vent can look like a welcome mat for mice. Cover exhaust fans and vents with a galvanized metal or copper screen with mesh to keep rodents out. Check the screens annually to ensure they’re still intact.

3. Close Holes in Cabinets and Closets

Mice love to burrow in tiny crevices in your kitchen cabinets and pantry. They also love to hide in small holes in the corners of closets (bedroom and coat closets). To prevent infestations in these areas, stuff the holes with steel wool and apply caulk to keep the holes sealed. 

4. Examine Exterior-Facing Items

Mice tend to cozy up in your home during cold months, and items like fireplaces, windows, and doors may allow them inside. Caulk your windows and doors before winter sets in. 

While mice can’t chew through bricks, they can still make their way down your chimney unless you keep the damper closed when the fireplace isn’t in use. Also, you’ll need to install a mesh-covered chimney cap to keep rodents out. Consider hiring a local chimney repair professional to help seal your fireplace.

5. Seal Gaps Around Pipes and Sewer Lines

Since indoor pipes lead to the outdoors, they present the perfect opportunity for mice to burrow inside. Check all the pipes around your washing machine, sinks, furnace, AC unit, and hot water heater. In addition, also inspect the gas, sewer, and water lines—use lath metal to seal any gaps around the pipes. 

6. Check the Attic and Basement

Mice love to camp out and build nests in your attic, basement, and crawl space. Stuff smaller holes with steel wool and use caulk to secure the area. For larger holes, attach metal sheeting to cover the gap.

7. Repair Damaged Fascia

Inspect areas where the gutters connect to the fascia board. Cracked or rotted boards will let in mice and bigger rodents, such as squirrels, and, of course, water. Get your fascia repaired as soon as possible to prevent unwelcome guests from entering your home.

8. Trim Trees

Remember when we said mice are good climbers? Tree branches reaching over your home are bridges for rodents. Keep tree branches trimmed, so mice don’t use them as direct pathways onto your roof and into your home.

9. Repair Roof Damage 

Your roof can suffer holes and cracks, especially after a major storm. You’ll want to check the eaves, soffits, gables, rafters, and vents for any holes or gaps. We recommend hiring a local roofer to examine your roof and fill the gaps with steel wool, lath metal, and metal sheeting. 

10. Fix Cracks in Your Foundation

Because your home’s foundation is close to the ground, it provides easy access for curious mice to enter. Take a walk around your home and look for small cracks and gaps in the foundation. Seal the gaps with silicone caulk, which is tough enough to withstand exterior elements and will keep mice out.

11. Fill Gaps in Garage and Exterior Doors

If your garage door or any doors that lead to the outside, such as a mudroom or sunroom door, are uneven or don’t have weatherproofing, a mouse can easily slip through the gaps. You’ll want to seal any cracks with silicone caulk and install weather stripping—which you can expect to cost between $129 to $427 per project.

12. Use Essential Oils

Find the entry points the mice use, such as the gap between the floor and wall, and apply peppermint oil—directly or diluted with water—to the area, or you can soak cotton balls in the oil and stuff them into mouse holes. Change out the cotton balls once a month to keep the smell potent. Mice dislike peppermint’s strong scent, but you can also try citronella, eucalyptus, and lemon. Keep in mind that peppermint oil is toxic for dogs and may not be safe for other household pets. Consult the instructions on the oil bottle and check with your vet before using any essential oils. 

How to Deter Rodents 

Even if you’ve sealed every crack and crevice and made your house impenetrable to rodents, it's best to keep those furry little critters far away from the property.

Here are the 10 most effective ways to deter rodents from coming near the inside and outside of your home:

1. Don’t leave any food, including pet food, out in the open.

2. Store food in airtight containers made from metal or glass instead of cardboard.

3. Clean the house regularly, especially after spilling food or drink. 

4. Store pet bowls in elevated and covered areas at night.

5. Don’t leave dirty dishes in the sink.

6. Keep wood piles at least 100 feet away from the house.

7. Regularly take out the trash, and make sure your garbage cans are securely closed and far away from the house. 

8. Remove bird feeders or move them at least 100 feet from the house.

9. Keep up with yard maintenance, like mowing the grass, picking up sticks, and trimming shrubbery.

10. Use physical deterrents like bright lights, strong smells, and traps.

Signs of Mice in Your Home

Mice are nocturnal, so you might not see them scurrying through your home during the day. Instead, there are other tell-tale signs that mice are partying in your pantry when you’re asleep. 

Here are the signs you might have mice: 

• Droppings: Mice typically leave ¼ inch droppings that resemble small brown pellets, while rats can leave much larger droppings. 

• Sounds: If you hear rustling or scratching sounds, you might have mice in your walls and ceilings. They also may be dashing around your floors in the middle of the night.

• Smells: If mice leave excrement and urine in your home, you’ll often smell a musky odor resembling ammonia.

• Holes: Mice love to chew tiny holes wherever they can. If you notice new holes in your baseboards, pantry, closets, or kitchen that are no larger than the width of a pencil, it's a sure sign that mice are afoot.

• Nibbles in food packaging: Mice typically tear into packaged foods (human and animal) looking for a snack. If you find holes in your favorite treats, discard them immediately as mice are most likely the culprit.

• Nests: Mice are resourceful, using everyday items such as fabric, plants, and paper to build nests. If you come across a ball-like nest behind your refrigerator, wall, or garage, call in a pro for removal. 

• Pet behavior: If your furry friend barks at the wall or starts chasing after something unseen in your home, they may have found a family of mice before you did. 

• Sightings: If you see one mouse, there are likely more hiding in your home.

Why Is It Important to Keep Mice Out of My Home?

While mice might look sweet and furry, they can turn your house upside down. Mice chew through food boxes, baseboards, and gas lines and leave their droppings anywhere, contaminating your dishes, food, countertops, and floors.

According to the Centers for Disease Control and Prevention (CDC), mice can also carry diseases, such as viruses and fevers. Mice are also avid breeders, quickly multiplying—and the last thing you want is a family of mice to make your house their home. For your health and safety, it’s crucial to cover mouse holes and seal your home from mice. 

How Much Does It Cost to Seal Your House From Mice?

We recommend consulting a pest control service near you to seal your home from mice. The average pest control service cost runs between $200 to $600, depending on the size of the infestation and the required solution. For example, filling a gap in a closet will likely cost less than filling a gap on your roof, which will require extensive equipment and labor. 

DIY vs. Hire a Pro

You can seal your house from mice yourself if you can get to your roof, crawl space, and other hard-to-reach places. You’ll need to purchase steel wool, caulk, and metal screens—you can expect these items to cost between $5 and $20 each, and you can purchase them online or at your local hardware store.

On the other hand, a professional pest control company near you will perform rat exclusion on your home, meaning they will seal off all entry points. Pros will seal holes, gaps, screen crawl spaces, and roof vents. You can expect the cost of a rat exterminator to run between $200 to $600.