Hearing scraping and scurrying sounds inside a wall late at night is unsettling — and a clear sign that you likely have mice in the house. Mice like to live inside walls, under floors, and in floor joists: it is warm, sheltered, and close to food.
This article helps you confirm whether it is mice you are hearing, find where they are getting in, and what you can do to deal with them — even when they are hiding in walls you cannot open.
What do mice in the walls sound like?
Mice are most active from midnight until early morning. The sounds are characteristic once you know what to listen for:
- Scraping and scurrying — rapid movements along tunnels inside the wall or floor
- Gnawing — a rhythmic, repeated sound when the mouse is working on wood, insulation, or cable
- Squeaking — young mice communicate with the female and can be heard as a thin squeaking sound
- Knocking — occasional taps against wooden surfaces as the mouse moves around
Rats produce heavier, more audible noise and move more slowly. If you hear light, rapid movements at night it is in all likelihood mice.
Try knocking on the wall where you suspect activity. A hollow sound can reveal a tunnel or space inside where the mice are moving.
Where do mice get into walls and floors?
Mice are remarkably flexible. They can squeeze through a hole that is 6 mm in diameter — roughly the same size as a pencil. Common entry points into walls and floors:
- Pipe penetrations in kitchens and bathrooms — the gap around pipes is often sufficient
- Cracks and gaps in the base and foundation wall near ground level
- Ventilation openings without mesh or with broken mesh
- Gaps behind refrigerators, dishwashers, and washing machines — appliances provide warmth and shelter
- Holes in floor joists from old pipe runs or electrical work
- Gaps along baseboards and door openings toward cold storage rooms or basements
Mice prefer to enter from below and work their way up. The crawl space is a common starting point — from there they can make their way up along pipes and into walls on all levels.
Confirm that it is mice — not rats or something else
Are you unsure whether it is mice or something else? Check these points:
- Droppings: mouse droppings are 3–6 mm, black, and pointed at the ends. Rat droppings are 12–18 mm and more cylindrical.
- Gnaw marks: mice leave small, shallow marks. Rats gnaw deeper and on coarser material.
- The sounds: mice sound light and rapid. Rats are heavier and more audible.
If you find no direct traces but continue to hear sounds you can sprinkle a little flour or talcum powder along a baseboard or in a cabinet corner. Paw prints the following morning confirm active movement.
How do you get rid of mice in the walls?
The difficulty with mice in walls is that you cannot reach them directly. The strategy must be based on directing the mice out of the wall and into traps, or luring them to baits that they carry back to the nest.
Step 1 — Place traps at the known movement points
The mice must leave the wall to search for food and water. Place snap traps or bait stations at the spots where you suspect they are coming out: along walls near pipe penetrations, behind appliances, and in cabinets near the floor. Use more traps than you think are needed — 6 to 10 in a home with active movement.
Step 2 — Remove access to food and water
Mice leave the wall to eat. Seal all food sources: store all dry goods in containers with lids, empty pet food bowls at night, and wipe down counters and floors in the kitchen every evening. The fewer reasons the mice have to come out, the more effectively they are affected by the traps.
Step 3 — Find and seal the entry points
This is the crucial step that prevents the problem from recurring. Inspect pipe penetrations, gaps in the base, and spaces behind appliances. Seal with steel wool (mice cannot gnaw through it) combined with acrylic filler or sealant. Do this step AFTER you have caught the mice — otherwise you will seal them in."
Step 4 — Electronic deterrence as a supplement
Ultrasound devices and bioacoustic mouse repellers can enhance the effect, especially in spaces such as the crawl space and storage room. They disturb the mice in their movement patterns and can contribute to them making their way out of wall spaces. Repello's mouse repeller covers up to 40 m² and works well in the rooms where you hear the most activity.
Can you hear mice in the floor?
Sounds under the floor follow the same logic as sounds in walls. Mice like to move under wooden floors and in floor joists, especially in older houses with a crawl space. The entry points are often the crawl space hatch, holes at pipe runs, or gaps at the exterior wall.
Sounds under the floor — scraping, scurrying — are virtually always a sign of rodents in the crawl space. Check the crawl space with a flashlight: look for droppings, gnaw marks on beams, and any nests made of paper or insulation material.
When do you need professional help?
There are situations where it is difficult to resolve a mouse infestation in walls on your own:
- You have had traps placed out for two weeks without results and still hear sounds
- The sounds are coming from multiple places in the house — a sign of a large and widespread colony
- You cannot find or access the entry points
- The crawl space is affected and you cannot inspect it properly
A pest control professional has access to a thermal camera and can locate the position of the nest without opening walls. They can also carry out a thorough sealing of all entry points as part of the treatment.
