How to Mouse-Proof Your Minneapolis Home Before Winter (Fall Checklist)

Every fall, it happens the same way. The first cold night hits, the furnace kicks on, and a few days later someone finds droppings in the silverware drawer.

That timing isn’t random. When temperatures in the Twin Cities start dropping in September and October, mice go looking for somewhere warm to spend the winter. Your house is warm, dry, and full of food, and if there’s a gap big enough, they’ll find it.

The good news: a couple of hours of work in early fall can keep most mice out. Here’s the checklist we’d follow on a typical Minneapolis home.

Why fall is the time to act

Mice are easier to keep out than to get out. Once they’re inside the walls, you’re dealing with trapping, cleanup, and sometimes a dead mouse smell. Sealing before they move in means you skip all of that.

Aim to finish this list before the first hard freeze, usually sometime in October.

Outside the house

1. Walk the foundation with a flashlight. Look for cracks, holes, and gaps, especially where the foundation meets the wood frame (the sill plate). In older homes with stone or block foundations, this is the number one entry point.
2. Check every spot where something goes through the wall. Gas lines, water spigots, A/C line sets, cable and phone wires, and dryer vents. Any gap around them bigger than a pencil is a way in.
3. Look at the garage door. Stand inside the garage with the lights off during the day. If you can see daylight at the bottom corners, mice can get in.
4. Check your vents. Dryer vents should have a working flap. Bath and kitchen vents should close. Crawl space and foundation vents need sturdy metal screening.
5. Look up at the roofline. Gaps at the soffits, roof returns, and gable vents let mice into the attic. They’re good climbers.
6. Trim back trees and shrubs. Keep branches a few feet from the roof and bushes off the siding.
7. Move the firewood. Stack it away from the house and off the ground. Same with mulch piled against the foundation.

Inside the house

• Basement: Check where pipes and wires come in, around the water heater and furnace, and along the top of the foundation walls.
• Kitchen: Look under the sink and behind the stove and dishwasher for gaps around pipes.
• Doors to the outside and garage: Add or replace door sweeps so there’s no gap at the bottom.
• Old basement windows: Seal gaps around the frames and replace broken glazing.

What to use (and what not to)

Mice can squeeze through a gap about 1/4 inch wide, and they chew through soft materials easily. Use materials they can’t get through:

• Steel wool or copper mesh packed into gaps, then sealed over with caulk or sealant
• Hardware cloth (galvanized wire mesh) for vents and larger openings
• Metal flashing for bigger gaps
• Door sweeps and garage door seals made with rodent guards

Avoid using spray foam by itself. Mice chew right through it. If you use foam, pack mesh into the gap first.

Clean up the food

Sealing matters most, but food is what keeps mice interested:

• Store pet food, bird seed, and grass seed in metal or hard plastic bins with lids, especially in the garage
• Keep pantry food in sealed containers
• Don’t leave pet food out overnight
• Clean up under bird feeders, or take them down in fall

When DIY isn’t enough

This checklist handles a lot. But call a professional if:

• You’re already hearing noises in the walls or ceiling
• You keep finding droppings after sealing
• The gaps are high up on the roofline
• You have an older home with a stone foundation (there are usually many small gaps)
• You think it might be rats, not mice

A technician can find the gaps you missed and seal them with professional materials. Learn more about our rodent exclusion and mouse-proofing service, or see what rodent control costs in Minneapolis.

Quick recap

• Seal before the first hard freeze
• Start with the sill plate, utility openings, garage door, and vents
• Use steel or copper mesh, hardware cloth, and flashing, not foam alone
• Store food in sealed containers
• Call a pro if you already have activity or can’t reach the gaps

If mice are already inside, our mouse exterminator page explains how removal works.

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.