Can mice climb walls?
By The Pest GuyLast updated
Yes, and the part worth acting on is not the climbing, it is where it puts them. Midlothian Council's pest control guidance is specific about one route in particular: if you have any creepers growing up the outside of your property, mice can use these to climb to roof level. So the question underneath this one, which is whether you have been looking in the right place, usually has an uncomfortable answer.
Most people proofing a house work at knee height. They check under the back door, around the pipe where it comes through the kitchen wall, along the skirting. All of that is right and none of it is finished, because a mouse that gets to the roof does not need any of the holes you just filled.
Once inside, the same guidance says they move around in ceiling voids and cavity walls, and Oxford City Council adds that mice often nest in hard-to-detect places such as under floorboards or in wall cavities. That is a mouse using the inside of your house as a corridor. It is also why the scratching people hear is so often above them rather than beside them, and why a gap you cannot find at floor level may simply be somewhere else entirely.
The measurement does not change with height, and it is the one number to carry up the ladder with you. Midlothian puts it as a gap beneath an external door of less than 6mm, with the test most people can actually apply: if you can get a pencil under a door, a mouse can get in. Oxford says the same of gaps around pipes. That is as true of a hole under a soffit as it is of one behind a washing machine, and the full guide to mice getting in sets out where to look and what to block it with.
What I am not going to tell you, and why
Search this question and you will be given numbers: how high a mouse can jump, how far with a run-up, and a list of which wall surfaces it can and cannot manage. I have left all of it out.
I could not find a source behind any of those figures, and none of them is about British housing stock. They also do not help. Knowing a mouse can jump some number of inches tells you nothing you can act on, because the mouse is not jumping up your wall, it is walking up something attached to it.
What the councils document is routes, and a route is a thing you can go and look at. A creeper, a climbing plant, a trellis, a downpipe run, a cable tray, ivy on a gable. Those are the sentences worth having, and they are the ones nobody quoting jump heights bothers to write down.
So where does that leave the proofing job
Go outside and look up before you buy anything. If something is growing up the wall, that is a ladder, and it is the specific thing the guidance names. The same goes for anything else running from the ground to the roofline that a small animal could use.
Then look at where that ladder arrives. Soffits, the gap where a roof meets a wall, loose or missing tiles, vents at high level. A mouse arriving at roof level does not need a hole any bigger than the one it would have used at the bottom of the door.
And if the evidence you have is up high rather than at floor level, settle what left it before you commit to a treatment. Droppings in a loft can be a mouse, and they can be several other things, and the answer changes what you do next: reading droppings properly narrows it down before anyone charges you. If what you have up there is a smell rather than droppings, read how long a dead mouse smell lasts first.
One honest limit. A climbing route at roof level on a two-storey house is not a stepladder job, and some of it will not be yours to fix at all: a creeper on a shared wall, or a defect at the roofline of a flat, can sit with a freeholder or a landlord. Worth settling whose problem it actually is before you pay someone, and what the work should cost before you accept a quote for it.
Can they climb into a bed, or up the stairs
Both get asked a lot, and the honest answer to both is that there is nothing special about either. A staircase is a series of steps a mouse can walk up, and a bed is furniture standing on a floor the mouse is already on. No source I would trust puts a limit on either.
What that means practically is that finding one upstairs is not evidence of anything unusual and does not change the job. It is still a question of what route they are using and where the gap is, and the gap is still about 6mm wide.
It is worth saying plainly, because the way these questions are usually answered online is designed to alarm. A mouse in an upstairs room is a mouse that found a way in and kept walking. It is a proofing problem, not an escalation.