Quick answer
To get rid of mice in walls, find where the cavity opens into rooms (behind kitchen units, under stairs, around pipes and radiators), remove nearby food, place a deterrent at those openings so mice leave the cavity, then seal the gaps with wire wool and sealant once activity stops. Avoid poison: mice that die inside walls cause smells for weeks.
Scratching inside a wall at night is one of the most unsettling signs of mice, because you can hear them but can't reach them. The good news is you rarely need to open the wall. Mice come out to feed, so you can work on the openings.
Signs of mice in the walls
Scratching, scurrying or faint squeaking inside walls, usually at night, is the classic sign. You may also find droppings near skirting boards, behind appliances or in cupboards that back onto the wall.
- Noises inside walls or ceilings at night
- Droppings along skirting boards
- Small holes at the base of walls or around pipes
- Grease marks along edges where mice run
- A musty smell near a particular wall
How mice get into wall cavities
Many UK homes have cavity walls, and older houses have voids behind lath and plaster, boxed-in pipes and under-stair spaces. Mice get in through gaps where pipes and cables pass through outside walls, damaged air bricks, and gaps under floors.
Inside, they come out where the cavity opens into a room: behind kitchen units, the kitchen plinth, around radiator pipes, under the bath panel and behind the boiler.
1find where they come out
Remove the kitchen plinth, look behind the cooker and fridge (safely), under the sink, behind the bath panel and around radiator pipes. Look for droppings, gnaw marks and holes.
2remove nearby food
Mice leave the cavity to feed. Store food in sealed containers, clean under appliances and don't leave pet food out overnight. Without food nearby, the cavity becomes far less appealing.
3deter them at the openings
Place a deterrent right at the openings you've found so mice are discouraged from using them. MintGuard peppermint balls fit neatly under the kitchen plinth, behind appliances and beside pipe openings. Each placement lasts around 30 to 60 days. Follow the pack instructions and keep out of reach of children and pets.
4seal the gaps once activity stops
When you've had a week or two without fresh droppings or noises, seal the openings with wire wool packed tightly and finished with sealant, or with metal mesh. Seal outside entry points too: pipe entries, damaged air bricks (using mesh, not blocking ventilation) and gaps under doors.
Sealing too early, while mice are still inside, can trap them in the wall.
Why not use poison?
Poisoned mice often retreat into the wall to die, where you can't reach them. The smell can last one to three weeks and attract flies. See our dead mouse smell guide if this has already happened.
| Method | In-wall problem |
|---|---|
| Poison | Mice die inside the wall, causing smells |
| Traps | Only work at openings; need checking |
| Deterrent at openings | Encourages mice to leave; seal after |
| Opening the wall | Rarely needed; costly |
When to call a professional
Call a pest controller if noises continue for more than a couple of weeks, you hear activity in several walls, you can't find the openings, or you suspect rats (heavier noises).
Common questions
How do I get mice out of my walls?
Find where the cavity opens into rooms, remove nearby food, place a deterrent at the openings, then seal the gaps once activity stops.
Will mice in the walls die on their own?
Not usually. They come out to feed. Without food and with deterrents at the openings, they tend to move on.
Can I hear mice in walls during the day?
Mostly at night, but you may hear them during quiet times of the day too.
Should I cut a hole in the wall to get mice out?
Rarely necessary. Work on the openings first. If a professional needs access, they'll advise.
How do I stop mice coming back into the walls?
Seal outside entry points around pipes and air bricks with mesh or wire wool and sealant, keep food stored, and refresh deterrents before winter.
Looking for a product? See our mouse repellent page.
Sources and further reading
Written by the MintGuard UK team
Researched from trusted UK sources and checked under our editorial policy. Last reviewed 26 October 2026.
