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.

A mouse in your wall isn't out to get you. It found warmth, food and a gap to get through. Poison doesn't close the gap. It spreads through bugs, owls, hawks and pets, and the next mouse walks right in. Seal the gap and nothing has to die.

Illustration of a small mouse sitting calmly
House mice often move indoors in autumn, when nights turn cold.2 They're following warmth, not waging war.
Start here

They're looking for shelter.

Mice don't choose your home out of spite. A house is a warm, dry cave full of crumbs, and every pipe, vent and seam in it is a possible door. When a mouse finds one, it moves in, and its family follows.

So the question was never how do I kill the mouse? It's how did it get in? Answer that, close it, and the cycle ends for good.

Killing the mouse inside doesn't close the door it used. The next one walks right in.

The hidden cost

Poison doesn't stay in the box.

Follow one poisoned mouse and you'll see why the "easy" fix spreads harm through the whole neighborhood, and still leaves the gap open.

55 of 59

dead burrowing owls tested on Marco Island, Florida had rat poison in their systems.5

Owls, hawks and foxes hunt mice for free. Poison turns them into casualties.

  1. 1

    The bait is built to be eaten

    Rodent baits are flavored to attract animals. Pets and wildlife can take the bait too, which is why the EPA requires locked bait stations around children and pets.

    Sources: NPIC, EPA
  2. 2

    The mouse doesn't die right away

    Most rodent poisons are anticoagulants: the animal bleeds internally and dies days to two weeks later. Sick and slowing down, it keeps moving: back to the nest, into the walls, sometimes out into the open.

    Source: EPA
  3. 3

    It often dies inside your walls

    Mice rarely travel far from their nest, so poisoned mice often die inside the house. That's the smell coming from inside the wall, where you can't reach it.

    Source: UC IPM
  4. 4

    The poison moves up the food chain

    An owl, hawk, fox, cat or dog that eats a poisoned mouse can be poisoned too. It's called secondary poisoning, and it reaches animals that never touched a bait box.

    Sources: NPIC, EPA
  5. 5

    And the gap is still open

    Nothing about the house changed. The next mouse finds the same opening, and the cycle starts again.

    Source: UC IPM: exclusion is "the most successful and permanent form" of control

What we’ve seen in the field: why not poison

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 that rodent poisons can harm children, and requires tamper-resistant stations wherever kids may be.

EPA3

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.

Fix the house,
not the mouse.

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.

Where they get in, highlighted.

Tap a number to label a spot. These 8 are the usual suspects on most houses.

Illustrated house with common mouse entry points marked in highlighter 8 marked spots: Roofline, soffit and fascia, Roof returns, Where building materials meet, Pipes and AC line sets, Utility penetrations, Weep holes and the foundation line, Garage door corners and bottom seal, Doors without sweeps. Use the numbered buttons to read about each one.

Based in part on the CDC's checklist of places to look.1 See all 8 entry points, 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, free.

Mouse-proof my house
Real houses

Real gaps, marked

Here are some of those entry points on real houses we’ve inspected. The highlighter shows where a mouse would get in.

See all the real examples

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

This weekend

Simple first steps.

No poison, no chemicals. Just a flashlight and an hour.

Walk the outside

Go slowly around the house with a flashlight. Look low (foundation, sill, crawl space vents) and high (rooflines, gables, soffits).

Use the finger test

If a gap is about as wide as your finger, a mouse can use it. Check every place a pipe, wire, cable or AC line goes through the wall.

Check the doors

Look for daylight under entry doors and at the bottom corners of the garage door. Doors and screens should fit tight.2

Take away the bridge

Mice are excellent climbers. Trim shrubs, vines and branches back from walls and the roof.2

Close the pantry

Store food, pet food and birdseed in sealed containers, and keep garbage lids tight.2

Pull the bait boxes

Ask your pest company what's in the black boxes around your house. If it's poison, ask what's being sealed instead.

Use materials that last. Soft plugs like plastic screening, rubber, vinyl or wood don't stop mice.2 Permanent repairs use stainless steel or galvanized hardware cloth and other exterior-grade metal, sealed in with exterior-grade adhesives and sealants so there's nothing left to gnaw. Getting that right on your house is what the custom guides below are for.

Want a second set of eyes?Send photos from your walk-around and we'll turn them into a plan: each gap marked, what to seal it with, and in what order.

Mouse-proof my house
Already have mice inside?

Lock the doors first. Then clear the house, once.

House mice and roof and Norway rats aren't native here. They arrived with people,2,7 and they can live inside alongside us for long stretches.2 So the ones you seal in have to come out.

  1. First

    Seal every way in

    Like locking your doors before you deal with a break-in. Until the gaps are closed, anything you remove is simply replaced by the next one.

  2. Then

    A one-time cleanout

    Remove the house mice and rats sealed inside with indoor snap traps, set where kids and pets can't reach them.2 Traps only ever go hand in hand with sealing, so this is a single cleanout, not a cycle.

  3. After

    Nothing has to die again

    With the house closed, there's nothing new to catch. No bait boxes, no monthly visits, no next generation in the walls.

Squirrels and anything bigger: one-way exits only.

They're let out through a door that only opens outward, then the opening is sealed behind them. Never trapped, never killed.

Never poison. It doesn't stay in the box, and poisoned mice often die inside the walls.2,3

Never glue traps. Animals caught on glue boards may not die quickly,2 and England made setting them for rodents a criminal offense in 2024.6

Sealing comes first.A photo-based plan, free, shows you which gaps to close, and in what order, so the next one has nowhere to come in.

Mouse-proof my house
Mouse-proof my house · Free

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.

  • Made from your photos, for your house
  • Prevention first. No poison, ever
  • Plain steps you or your contractor can follow

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

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

Take a break

The arcade. Learn by playing.

Three quick games about how mice get in, and why sealing beats poison. Best on a tablet.

Endless · farthest run

Mouse Run

Run as a mouse through the house at night. Dodge the cat and the broom. Skip the poison.

Play Mouse Run

Open the arcade

The whole idea

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.