No Mice Here Mouse-proof my house
A field guide to sealing your home for good

It’s not a mouse problem. It’s a house problem.

Mice get in through gaps about the width of your finger. Find them, seal them for good, and they stop coming back. No poison, no monthly service.

Mouse-proof my house Send photos, get a marked-up plan Start the free check

Built by a specialist with 25+ years sealing homes, starting in Connecticut. No poison, ever.

  • Free check
  • No sign-up
  • No poison
  • A flashlight and an hour
Illustration of a small mouse sitting calmly
Mice don't wait for cold weather. They work year round to find and use the gaps a house gives them.

How it works

Check. Plan. Seal.

  1. Check

    Walk the 10 spots with a flashlight and use the finger-width rule.

  2. Plan

    Get your gaps in order, what to buy and how to fix each one. Choose which gaps you’ll do and which go to a pro.

    Sample house check result listing the 10 spots: four marked Gap found, five Looks sealed and one Check again.
    A sample result, made with example answers.

  3. Seal

    Seal each gap with hardware cloth or metal, sealed with exterior-grade construction sealant, and check it off. Re-check at least once a year, and after storms or any work on the house.

Start the free check
The real fix

Any home can be mouse‑proofed.

Mouse-proofing means finding every opening a mouse or rat can use and closing it permanently, so the house itself keeps them out. Brick, block, stucco and sound siding already do that job. The weak spots are where things meet: pipes, wires, vents, rooflines and doors.

about a finger wide
a seam where boards meet

If a gap is about as wide as your finger, a mouse can use it. Even a thin crack where two materials meet, like boards that only touch at the corners, can be gnawed open into a mouse-sized hole. Seal the seams, not just the obvious holes. Also called the pencil or pinky test. A young mouse needs only a 1/4-inch gap, about the thickness of a standard pencil, to get its skull through. If the skull fits, the body follows.

Where they get in, highlighted.

Tap a number to label a spot. These 10 are the usual suspects on most houses, two of them round the back.

Illustrated house with common mouse entry points marked in highlighter 10 marked spots: Roofline, soffit and fascia, Roof returns, Where building materials meet, Pipes and AC line sets, Utility penetrations, Foundation and sill line, Garage door corners and bottom seal, Doors without sweeps, and at the back of the house, Low decks, Bulkhead and cellar doors. Use the numbered buttons to read about each one. BACK OF THE HOUSE

Based in part on the CDC's checklist of places to look.1 See every entry point, with a how-to for each

Not sure where your gaps are?Send us photos of your home and we'll mark them for you in a custom plan. The basic check is free, and the full-house plan is free for our first 10 homeowners.

Mouse-proof my house Send photos, get a marked-up plan
Real houses

Real gaps, sealed

Here are some of those entry points on real houses we’ve inspected. The highlighter shows where a mouse would get in. Tap or click a before and after photo to see the same spot sealed.

  • Close-up of a roof return on a shingle roof, where the weathered trim meets the shingles with a dark gnawed opening under it. Before
    Roof return: a gnawed opening where the trim meets the shingles. Out of sight from the ground, and wide open.How to fix it: Roof return
  • Looking up at an eave corner: a dark open slot runs down the fascia where it meets the soffit.Before
    The same eave corner after sealing, seen from a different angle: the fascia and soffit meet with no opening.After
    Eave corner: before, an open slot where the fascia meets the soffit. After, the same corner closed (shot from a different angle).How to fix it: Roofline and soffit
  • A stepped fascia corner where two roof lines meet, with a dark gap at the corner just above the lower roof edge.Before
    The same stepped fascia corner after sealing: the corner is closed.After
    Stepped fascia corner: before, a gap where two roof lines meet. After, the same corner closed.How to fix it: Roofline and soffit

See all the real examples

Before and after photos from real homes we've inspected and sealed, with the entry point marked in highlighter. Cropped so nothing identifies the house.

Who pays for it

Every bait box has a guest list.

Owls and hawks

The animals that hunt mice for free are the ones poison hits hardest. Hawks and owls face high secondary poisoning risk from the strongest anticoagulants.

NPIC rodenticide fact sheet4

Cats and dogs

Dogs dig for flavored bait. Cats eat what they catch.

NPIC4

Kids

The EPA warns rodent poisons can harm children and requires tamper-resistant stations where kids may be.

Mice come in for shelter and leave allergen in the dust. A national survey found it in 82% of U.S. homes, and in preschoolers with asthma who are allergic to mice, more allergen at home meant more days with symptoms.

EPA3 · NIEHS survey8 · Johns Hopkins study9

Your home

A mouse that dies in a wall void leaves an odor you can't reach and a sanitation problem behind the drywall.

UC IPM2

The cycle

Poison treats the mouse, not the opening. You end up paying to repeat it.

Mouse-proof my house · Free basic check

A plan for your house.

Send us photos of your home and a few answers. We'll send back a custom how-to guide that marks each gap, says what to seal it with, and puts the steps in order.

The basic check is free. The priority full-house plan and the live video walk-around are free for our first 10 homeowners.

  • Made from your photos, for your house
  • Prevention first. No poison, ever
  • Plain steps you or your contractor can follow
Selfie of Paul Trapp, the exclusion specialist who built this guide, outdoors under a cloudy sky.

Paul TrappBuilt by a rodent and wildlife exclusion specialist with 25+ years in the field, starting in Connecticut.

Show us the house. We'll show you the gaps.

It takes about five minutes, and your phone camera is all you need.

Mouse-proof my house Send photos, get a marked-up plan

Just one gap you’re not sure about? Send us a photo →

We'll never sell your info. How we handle it

Questions

Common questions

More in Get help.

Sources for this page are on Why not poison.

Is Check my house free?

Yes. There’s no sign-up and nothing to buy. It runs in your browser.

How small a gap can a mouse use?

About the width of your finger. That’s the finger-width rule, and it’s why the check asks you to look closely at seams, corners and pipe holes.

Can mice affect allergies or asthma?

They can. Mice leave allergen in household dust, and a national survey found it in 82% of U.S. homes. NIEHS researchers found that in people with allergies, higher levels at home were linked to more asthma symptoms. If someone in your home has asthma, ask their doctor about mouse allergy. Mice come in for shelter, so sealing the gaps keeps new ones out, with no poison, ever.

Start the free 10-spot check →

Sources: NIEHS national survey8 · NIEHS asthma study10

The pledge

Poison doesn’t close the gap.
Sealing does.

Close the way in, clear out the few already inside, and nothing has to die again: not the next mouse, not the owl, not the family dog.

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