If you’ve heard scratching sounds under the floor late at night or spotted droppings near the skirting boards, you might be wondering just how long mice can actually live under your floorboards. It’s not a pleasant thought, but it’s something you need to know if you’re dealing with—or trying to prevent—a mouse problem in your home.
The truth is, mice can survive under floorboards for a long time. If the conditions are right, they can live there for months. In some cases, they might stay hidden for over a year without ever being seen. It all depends on a few key things—what they can find to eat, how safe they feel, and whether anything drives them out.
So let’s walk through what really keeps mice under floorboards, how long they stick around, and what you can do to stop it.
Why do mice go under floorboards in the first place?
You’re not going to find mice living out in the open. They prefer quiet, dark places where they feel safe and hidden. Floorboards tick all the boxes.
They’ll squeeze through gaps, cracks, or holes—especially where pipes and cables go through walls and floors. Once they’re in, they’ll explore. If they find warmth, shelter, and access to food nearby, they’ll stay.
Places under floorboards give mice:
- Protection from predators
- Consistent warmth, especially if there’s underfloor heating
- A clear run between rooms
- Nesting spots with soft insulation or dust
- Easy access to kitchens or food cupboards if there’s a gap nearby
Once they’re in, they don’t usually want to leave.
So, how long can they survive down there?
If nothing changes and they keep finding food, mice can live under floorboards for a long time. Some mice can survive over a year in the same spot. Their lifespan in the wild is shorter—usually around 12 months—but when they live indoors, they’re better protected.
Mice need three main things to survive:
- Food
- Water
- Shelter
If you’ve got crumbs, pet food, cereal boxes, or bin bags lying around, that’s enough to feed them. They don’t need much. A few crumbs a day will do. They also get water from condensation, leaky pipes, or even moisture in the food itself.
As long as they’re not disturbed and they can keep feeding, they’ll keep nesting and breeding. That’s when the problem grows. You might start with one or two mice, but before long, you could be dealing with a whole colony.
What keeps them there?
You might be hoping they’ll just move on. But unless you take away what’s keeping them there, they won’t go anywhere.
Here’s what encourages mice to stay under your floor:
- Easy access to food. Even a few dropped crumbs or an open food bag can feed a mouse for days.
- Warmth. Floorboards close to heating pipes or insulation are cosy.
- Darkness. They prefer places where no one bothers them.
- Nesting material. If they find soft bits of insulation or paper, they’ll use it to build nests.
It’s not just that they can survive under the floor. It’s that your home, if left unchecked, makes it easy for them to do so.
What happens if they breed under the floor?
Mice don’t just survive—they multiply. A single female can have five to ten litters a year. Each litter can have around six to eight babies. That means dozens of mice in a short space of time.
And they don’t wait long. Mice start breeding when they’re around six weeks old. So that one mouse you saw? It might already have a family underneath your feet.
Once they’ve set up a proper nest, things move fast. More mice means more droppings, more noise, and more damage. You’ll hear scratching, gnawing, or rustling sounds at night. You might even start to smell them.
Can mice live under the floor without being noticed?
Yes, they can. A lot of the time, mice under floorboards go unnoticed for weeks—or even months. Especially in quiet rooms or second homes. You might not spot the usual signs straight away.
They move mostly at night, when everything’s quiet. If they’re under carpeted floors or thick boards, you might not hear much. But that doesn’t mean they’re not active.
Look out for:
- Tiny droppings near walls or corners
- Smudge marks along skirting boards
- Gnaw marks on food packaging or wires
- A faint musky smell that won’t go away
- Pets acting alert or staring at certain spots
Once you’ve seen these signs, the mice have likely been there for a while.
Can mice stay alive without regular food?
They don’t need much to live on. A single mouse can survive on a few grams of food a day. And they’re not picky. They’ll eat:
- Bread crumbs
- Pet food
- Leftovers
- Dry food in unsealed bags
- Grease and food waste around cookers or bins
Even if your home is mostly clean, mice can still find bits to nibble. They’ll explore the entire space once it’s quiet. So if your kitchen is upstairs and your floorboards are downstairs, don’t assume they’re separate. Mice can travel between floors through wall cavities or pipe holes.
Will they ever leave on their own?
Not usually. If they’ve found everything they need, they’ll stay. They don’t just pop in for a night and leave again. Once they’ve built a nest and got a route to food, they treat your floor as their home.
They’ll only leave if:
- You block access to food
- You seal entry points so they can’t return
- You disturb their nest
- The population gets too large and they’re forced out
Otherwise, they’ll stay—and breed—until something forces them to go.
What problems can they cause while they’re under your floor?
Mice don’t just sit quietly under the floor. They chew, they scratch, and they leave mess behind. Over time, this causes real damage.
Some of the issues include:
- Chewed wires – which can lead to electrical faults or even fires
- Damaged insulation – especially in older homes with wool or foam insulation
- Structural weakening – from constant chewing at wood or supports
- Smell and hygiene issues – from urine, droppings, or dead mice
You might not notice all the damage until you lift a floorboard or get a professional in. By then, you could be facing repair costs as well as pest control bills.
How do you get rid of them?
If you think mice are living under your floorboards, you need to act quickly. It’s much easier to deal with a small number early than a full infestation later.
Step 1: Cut off their food supply
- Clean up crumbs straight away
- Store dry food in sealed containers
- Clear pet bowls at night
- Keep bins shut and emptied often
Step 2: Find and block their entry points
- Look around pipes, cables, and floor edges
- Fill holes with wire wool and sealant
- Use door sweeps to block gaps under doors
Step 3: Set traps or use professional control
You can try traps, but they need to be placed correctly—usually along walls or near entry points. Poison is available, but it can be risky if you’ve got pets or children. And poisoned mice might die under the floor, causing even more problems.
If it’s a big issue—or you’re not sure how bad it is—it’s worth calling a pest control expert. They’ll check all the likely nesting spots and use safe, effective treatments to clear the infestation.
What if the mice die under the floor?
It’s not something anyone wants to think about—but it happens. If a mouse dies under the floorboards, you’ll know about it. The smell can be strong, especially in warm weather. It usually lasts for a few days to a couple of weeks, depending on how deep the body is and how big the mouse was.
In some cases, the only way to deal with it is to lift the floor and remove the carcass. Another reason why poison needs to be used carefully.
Can you stop mice from coming back?
Once you’ve cleared the infestation, you want to keep it that way. The key is prevention.
- Seal every possible entry point—even tiny ones
- Keep food sealed and stored
- Stay on top of cleaning, especially in hidden corners
- Regularly check lofts, basements, or unused rooms
- Set up traps as a warning system if needed
It’s much easier to keep mice out than to get rid of them once they’re in.
Final thoughts
So, how long can mice live under floorboards? The answer is—long enough to cause real problems. If they’ve got food, warmth, and shelter, they can stay hidden for months. They’ll breed, chew, scratch, and make themselves at home right under your feet.
If you suspect mice are living under your floor, don’t wait. Take action early. Block their access, remove their food, and consider calling in professionals if things are getting worse.
Mice won’t move out just because you want them to. You’ve got to make it hard for them to stay.
