Where do mice hide in a house?

How a mouse chooses a spot

Three criteria, in this order, and they explain everything else on this page.

Within easy reach of food. A house mouse typically forages within about ten to thirty feet of its nest. That short range is the single most useful diagnostic fact on this page: if you have droppings in a kitchen cupboard, the nest is almost certainly in that room or the wall behind it, not in the loft.

Dark, enclosed and tight. A mouse feels safe with its body in contact with surfaces on several sides. An open shelf is not a nest site; the gap behind the shelf unit is. This is also why mice travel with one shoulder against a wall and almost never cross open floor.

Warm and undisturbed. A boiler cupboard, a hot water pipe run, the warm void behind a refrigerator's compressor, an engine bay that was warm a few hours ago. Warmth is also why autumn brings them indoors in the first place.

Add in the entry requirement — a mouse gets through a quarter-inch gap, about the width of a pencil — and the list below writes itself.

The twelve places, in the order worth checking

1. The kick space under kitchen cabinets. The void behind the toe-kick board is usually open to the wall cavity and sits directly under the food. This is the most common house mouse nest site in an American home, and it is also why traps along the cabinet base work so well. Mice in the kitchen is the full room-by-room treatment.

2. Behind and underneath the refrigerator. Warm from the compressor, dark, never cleaned, and there are crumbs. Pull it out and look at the floor and the back of the unit.

3. The cabinet under the sink. Where the water and waste pipes pass through the wall or floor is the most common entry point in the whole house, and there is usually a nest within a few feet of it.

4. Underneath and behind the stove. The gas line penetration, plus the warmest floor space in the room.

5. Inside wall cavities. Especially near pipe and cable penetrations, and in the vertical runs between floors. If you hear scratching behind plaster at night, that is this. Mice in walls covers it properly.

6. Loft and attic insulation. Tunnelled runs through the insulation, often near a water tank or where the pipes come up. Shredded insulation is the tell. Best mouse traps for attic is the right category up there.

7. Stored cardboard boxes. A box of papers or clothes in a garage, basement or spare room is a nest with building material included. Mice shred cardboard and paper into exactly the material they want.

8. Behind the washing machine and dryer. Warm, enclosed, undisturbed and rarely moved. The dryer vent run is also a frequent entry path from outside.

9. Inside upholstered furniture and mattresses. A sofa in a garage, a mattress in storage, a car seat. Foam is ideal nesting material and the cavity is already dark.

10. Garage and basement corners, especially behind shelving, inside stacked plant pots, in a stored barbecue cover or under a pile of timber. Mice in the garage and best mouse traps for basement deal with these.

11. Near a boiler, water heater or pipe run. The warmest enclosed space in the building, and the one mice choose first in a cold snap.

12. A vehicle engine bay or cabin. Particularly a car parked in a garage and not driven daily. Shredded cabin filter, nesting material on the airbox, chewed wiring insulation. Best rodent repellents for cars is the prevention page.

Where they are not

Worth saying, because it saves you time:

• The middle of a room. Mice travel on edges. An open floor is a threat.
• A bright, busy, frequently-used space. They will cross one at night to reach food, but they will not nest there.
• Deep inside a chest freezer or a cold room. Too cold.
• A sealed, hard-sided container. They chew through cardboard and bags, not glass or metal — which is the whole argument for moving food into hard containers.

Confirming a nest rather than guessing

Four signs, in rough order of reliability:

Droppings, concentrated. Dark, rice-grain sized, pointed at the ends. Scattered droppings mean a travel route; a dense pile in one spot means you are at or near the nest.

Nesting material. Shredded paper, insulation, fabric, cardboard or foam packed into a void. This is the definitive sign.

Rub marks and runways. Greasy dark smears along a skirting board or around a hole, from oil in the fur. They build up on routes used nightly.

Noise at night. Scratching or scurrying in a wall or ceiling between dusk and the small hours. Mice are mostly nocturnal, so a 2 a.m. noise is normal and a daytime sighting usually means a larger population.

And a smell. A persistent musky ammonia smell in a confined space means accumulated urine and nesting material. How to get rid of mouse smell deals with that, and signs of mice in the house covers the full checklist.

A flour or talc trick is useful if you are unsure: dust a thin layer along a suspected run overnight and look for footprints and tail drags in the morning.

What to do once you have found the spot

Do not simply clear the nest out and hope. The sequence that works:

Trap first, along the route, not at the nest. Set traps flat against the wall between the nest and the food, with the trigger end toward the wall. Several of them. The runway is a far better trap location than the nest itself. Where to place mouse traps and how to set mouse traps have the technique.

Then clean, wet. Spray the nest and droppings with disinfectant, wait five minutes, pick everything up with paper towels and bag it. Never sweep or vacuum dry rodent material — see cleaning up mouse droppings.

Then seal. Trace back from the nest to the gap it came in through — under the sink, behind the stove, the dryer vent, a utility penetration on the outside wall. Pack with stainless steel wool or quarter-inch hardware cloth and seal over.

Then remove the reason. Food into hard containers, pet food in a bin with a lid, clutter and cardboard out of the garage. A nest site with no food nearby does not get reoccupied.

Keep two traps set as permanent monitors afterwards. How to get rid of mice is the complete sequence if you are starting from scratch.

The short version

Look for dark enclosed voids within thirty feet of food, near warmth, along walls rather than in the open: the cabinet toe-kick, behind the refrigerator and stove, under the sink, the wall cavity, the loft insulation, stored boxes, behind the washer, inside stored furniture and the engine bay of a car that does not move. Confirm with concentrated droppings and shredded nesting material, trap on the runway rather than at the nest, clean wet, and seal the hole.