Why mice keep coming back every year

If you’ve had mice every fall for the past few years, you’re not unlucky. Your house has openings, and every year, a new group of mice finds them.

Traps and bait only deal with the rodents that are already inside. They don’t do anything about the next ones. Rodent exclusion is the part that actually stops the cycle. It means finding every gap a mouse or rat can squeeze through and sealing it with materials they can’t chew.

It’s the least exciting part of pest control and the most important one.

What is rodent exclusion?

Exclusion (also called rodent-proofing, mouse-proofing, or rat-proofing) is the process of physically blocking rodents from getting into a building. A trained tech inspects the whole structure, from the foundation to the roofline, and seals:

• Gaps and cracks in the foundation
• The sill plate, where the house frame meets the foundation
• Openings around pipes, wires, gas lines, and A/C lines
• Garage door corners and worn weatherstripping
• Dryer vents, exhaust vents, and crawl space vents
• Gaps under exterior doors
• Soffits, roof returns, and gable vents
• Openings around chimneys and roof penetrations

How small a gap can a mouse get through?

Smaller than you’d believe. A mouse can squeeze through a gap about 1/4 inch wide, roughly the size of a dime or the width of a pencil. A young rat can get through a gap about 1/2 inch wide, roughly the size of a quarter.

If their head fits, the body follows. That’s why the obvious holes are just the start.

Materials that actually stop rodents

Where mice usually get into Minneapolis homes

From what technicians see across the city, the same spots come up again and again:

1. The sill plate. In older homes with stone or block foundations, the sill plate often has gaps all the way around the house.
2. Garage door corners. The bottom corners of garage doors wear out and give rodents an easy way in.
3. Utility line entries. Gas, water, cable, and A/C lines often have unsealed gaps where they go through the wall.
4. Dryer vents. A broken flap is an open door.
5. Basement windows. Old windows with gaps around the frame.
6. Roof returns. Where the roofline meets the wall, there’s often a gap rodents can climb into.

Do freeze-thaw cycles open new cracks?

Yes. Minnesota’s freeze-thaw cycles are tough on houses. Water gets into cracks, freezes, expands, and widens them. Soil shifts and foundations settle. Caulk and sealants dry out and pull away. Ice dams can damage soffits and fascia.

That’s why exclusion isn’t always a one-and-done forever fix. Most good exclusion work lasts for years, but a quick check every year or two catches any new gaps before rodents do.

How our exclusion service works

1. Full inspection. Inside and outside, foundation to roofline. Every gap is noted.
2. A clear plan and price. You’ll see what needs sealing and what it costs before work starts.
3. Sealing. Gaps are closed with the right material for each spot.
4. Removal of rodents already inside. Usually done at the same time, so you don’t trap rodents in your walls. See mouse removal and rat removal.
5. Follow-up. The tech confirms activity has stopped and checks the work.

What keeps rats and mice away permanently?

Honestly, nothing is permanent with rodents, but this gets close:

• Seal every gap with chew-proof materials
• Keep food in sealed containers, including pet food and bird seed in the garage
• Keep firewood, mulch, and clutter away from the foundation
• Trim shrubs and branches back from the house
• Keep garbage and compost in sealed bins
• Check the outside of your house every fall before it gets cold

Exclusion for businesses and rental properties

For restaurants, warehouses, and multi-unit buildings, exclusion is the best investment you can make in rodent control. Dock door seals, door sweeps on all exterior doors, sealing utility penetrations, and wire mesh on vents protect inventory and tenants. Pair it with a regular monitoring program, and you’ll catch issues before they turn into complaints.

Rodent exclusion FAQs

What is rodent exclusion?

Rodent exclusion is the process of physically sealing a building so mice and rats can’t get in. A tech finds every gap in the foundation, walls, utilities, vents, doors, and roofline and seals them with chew-proof materials like steel mesh, hardware cloth, metal flashing, and rodent-resistant sealants.

How small a gap can a mouse get through?

About 1/4 inch, roughly the size of a dime. A young rat can fit through about 1/2 inch, roughly the size of a quarter. If a rodent’s head fits through an opening, its body can usually follow.

How much does exclusion cost?

For a typical Minneapolis home, exclusion often runs from about $300 to $1,500 or more. The price depends on how many gaps there are, how big they are, and how hard they are to reach. You’ll get an exact price after the inspection.

What keeps rats and mice away permanently?

Sealing every entry point with chew-proof materials is the most effective step. Pair that with storing food in sealed containers, keeping clutter and woodpiles away from the house, trimming branches, using sealed garbage bins, and checking the outside of your home every fall.

How long does exclusion last?

Quality exclusion work often lasts for years. Minnesota’s freeze-thaw cycles, settling foundations, and weather can open new gaps over time, so a quick inspection every year or two is a good idea to catch new problems early.

Where do mice usually get into Minneapolis homes?

The most common spots are gaps at the sill plate, worn garage door corners, unsealed utility line entries, broken dryer vent flaps, old basement windows, and roof returns. Older homes with stone or block foundations tend to have the most gaps.

Do freeze-thaw cycles open new cracks?

Yes. Water gets into small cracks, freezes, and widens them. Foundations settle, sealants dry out, and ice dams damage the roofline. That’s why homes in Minnesota benefit from a quick exclusion check every year or two.

Mouse-proofing near you

We connect homeowners and businesses in Minneapolis, Brooklyn Park, Edina, Richfield, and beyond with local exclusion pros.

Other rodent services

Norvane Rodent Control is a free referral service. Calls are connected to independent, licensed pest control providers serving the Twin Cities. We do not perform pest control services ourselves. Learn more.