How to Keep Mice Out of an Old House in Western New York

Western New York has a lot of beautiful older homes: farmhouses, Victorians in Buffalo neighborhoods, village homes with fieldstone foundations. They have character, and they also have a century or more of settling, patching and additions. That gives mice plenty of ways in, especially once the weather turns cold in the fall.

How are mice getting into my old house?

Mice follow walls and edges, and they look for warm air leaking out. In older homes, the most common entry points are:

• Sill plates. The wooden beam where the house sits on the foundation often has gaps, rot or uneven spots, especially in older framing.
• Utility penetrations. Gaps around gas lines, water pipes, dryer vents, cable and electrical lines, and old abandoned openings from past upgrades.
• Garage doors. Worn or missing bottom seals and gaps at the corners of the door are an easy path into an attached garage, and from there into the house.
• Stone and block foundations. Mortar crumbles with age, and fieldstone foundations have many small voids. Hollow block walls can act like highways.
• Rooflines and chimneys. Mice climb well, so gaps at soffits, eaves and around chimneys matter too.
• Bulkhead and basement doors, crawl space vents and old coal chutes.

How small of a gap can a mouse fit through?

Smaller than most people expect. A house mouse can fit through an opening about the size of a dime, roughly a quarter of an inch. If you can fit a pencil into a gap, assume a mouse can use it. That's why a careful inspection matters more than spotting one big hole.

Why don't traps alone solve a mouse problem?

Traps are useful, and we use them. But traps only deal with the mice already inside. If the entry points stay open, new mice keep arriving, especially in fall and winter. Mice also breed quickly, so catching a few rarely catches up with the population.

Other common reasons traps seem to fail:

• They're placed in the middle of a room instead of along walls where mice travel.
• There are too few of them for the size of the problem.
• Food sources nearby, such as pet food, bird seed or pantry goods, are more appealing than the bait.

What does a long-term mouse plan look like?

We follow three steps:

1. Inspect. We look at the whole house, from the foundation and sill plate to the garage, utility lines and roofline, and note droppings, rub marks and nesting signs to find where mice are active and how they're getting in.
2. Seal. We close entry points with materials that mice can't chew through, and we focus first on the openings they're actually using.
3. Monitor. We use traps or tamper-resistant stations to deal with mice already inside, then check back to confirm activity has stopped and no new gaps have opened.

What materials keep mice out?

Mice can chew through foam, wood, rubber and plastic. The best sealing materials include:

• Copper mesh or stainless steel wool packed into gaps around pipes, then sealed over
• Hardware cloth (heavy metal mesh) for vents and larger openings
• Sheet metal flashing for gaps at sill plates and corners
• Mortar or concrete patch for foundation holes and crumbling stone joints
• Heavy-duty door sweeps and garage door seals with rodent-resistant inserts

Expanding foam alone isn't a good long-term barrier, because mice chew right through it. It works best combined with metal mesh.

How do I clean up mouse droppings safely?

Some wild rodents can carry hantavirus. In the northeastern U.S., the deer mouse and white-footed mouse are the main concern. The CDC recommends cleaning up rodent droppings safely rather than sweeping or vacuuming them, which can stir particles into the air.

The CDC's basic steps are:

• Air out the space for at least 30 minutes before you start.
• Wear rubber, latex or vinyl gloves.
• Spray droppings and nesting material with a disinfectant or a bleach-and-water solution and let it soak for about 5 minutes.
• Wipe it up with paper towels, then bag and throw it away.
• Disinfect the area, then wash your gloved hands, remove the gloves and wash your hands again.

For heavy contamination in attics or crawl spaces, follow the CDC's guidance for larger clean-ups or ask us about options.

Keeping mice out of old houses FAQs

Why do I get mice every fall?

As temperatures drop in Western New York, mice look for warm shelter and food. Older homes with gaps at the foundation and sill plate are easy targets. Sealing before fall makes a big difference.

Can mice get in through a stone foundation?

Yes. Mortar in older stone foundations wears away over time, leaving voids that mice can use. Repointing or patching those gaps is often part of a long-term fix.

Will steel wool keep mice out?

Steel wool or copper mesh packed into a gap and sealed over works well for small openings. Copper mesh doesn't rust, so it holds up better in damp spots.

Do ultrasonic repellers work for mice?

Research on plug-in ultrasonic devices has been mixed, and they don't stop mice from getting in. Sealing entry points is far more reliable.

Is your mouse exclusion work warrantied?

Yes. Our exclusion work comes with a written warranty. Length and terms vary by service, and we'll explain exactly what's covered before we start.

Get a free mouse inspection

Gernatt Pest Solutions is a family-owned company serving Western New York. Owner Ben Gernatt has been in the pest control industry for over 20 years. We offer free estimates and warrantied exclusion work, and we'll show you exactly where mice are getting in. We can't promise a home will never see another mouse, but we'll make it much harder for them.

Call (716) 605-5676 or email info@gernattpestsolutions.com.