Often I get questions asking what should be done to catch a mouse, but much less frequently do I get asked how to keep mice out. From a pest management professional's point of view, discovering how the mouse got inside in the first place would be my main mission. Sure, I'm interested in capturing the little rascal before he urinates and leaves his droppings all over my pantry items, but I know, again, from a professional point of view, that catching a mouse is a fairly simple task which can be done, in most cases, overnight.
I want to make sure that once I have eliminated the intruder, its relatives do not come calling. So, knowing the habits of the house mouse or field mouse is very important to gaining the upper hand in learning how to keep mice out.
The first thing is to closely examine the exterior of your home for entry points. Mice are great climbers, so you need to look high and low. Inspect any place
where pipes or conduits come through a wall. Electrical lines, plumbing fixtures, air conditioning conduits, hose bibs and clothes dryer vents should all be totally sealed around their edges. It only takes a hole the size of a dime for a mouse to gain entry. That is only about one-half inch, but that is all it needs to squeeze its head through. The rest of its body can elongate itself and wiggle its way inside. I like a product called Xcluder for sealing up holes. It's inexpensive and very easy to use.
Most often we find mice get inside by getting under worn or missing garage door thresholds. New thresholds must be installed every few years to keep seals tight. Make sure the seals go all the way across the door to include edges. Same for pedestrian doors. If you can see light streaming under the door you can assume that the door will not stop a mouse. Hold a dime on its edge and see if you can hold it upright under the door threshold. Smart Park has a kit that includes everything you need to replace the garage threshold.
Mice love the cover of tall grass along foundation walls. You might think having nice, lush grass along the foundation wall looks good, but the negative aspect is that it gives mice the cover they seek. Eliminating vegetation along walls is one of the things we require of our commercial customers. Homeowners may be less willing to have a uniform bare strip running along their foundation walls, but, at the very least, keep this strip cut very low. Behind the cover of tall grass, mice can gnaw on lose or missing motor joints and discover an entryway into your house. Roundup herbicide does a nice job of knocking down unwanted vegetation along foundation walls.
Be sure to check joints where sidewalks meet the foundation of the house. Old or worn away joint filler can leave cavities that may provide access under slabs or expansion joints leading under slabs. If a mouse can get under a slab and burrow, it may eventually find where toilet plumbing comes up through
the slab into your home. Replacement joint fillers can be made of everything from rigid board impregnated with a blend of asphalts to cork fiber to rubber and more. I don't care what you use, as long as there is something filling that expansion joint.
As for the holes on the outside of the house I suggest using a quick setting concrete patch using a product like Quikrete. If the hole is meant to allow the passage of air you don't want to seal it, but you can fill it with the Xcluder stainless steel wool product I previously mentioned. Regular steel wool eventually rusts once wet and it is not recommended to fill these holes. You can also use hardware cloth to cover holes. Hardware cloth, which is not cloth at all, but rather a mesh of galvanized metal, comes in a roll and costs about $8.00 for a 3' x 4' sheet. You need a sheet metal cutter to cut it, but it is a very inexpensive way to seal up holes and rodents cannot chew through it.
Follow these suggestions and you will do a pretty good job of securing your castle from invading rodents.
04 Feb 2013, 14:19
We have seen two mice coming up from the gas line in the floor of our
family room next to our woodburning fireplace. I put some steel wool in
the hole and think I have found the outside entry. The air conditioning
conduit seems to have the foam all gnawed off. I put steel wool in that
hole as well. If there is mice inside, will they die and/or where will
they go? If they die will I smell them?
06 Feb 2013, 18:18
there is a small gap under my foundation were mice are coming up into the
walls however they are stuck in the wall nowhere for them to get out. i am
planning on sealing the gap but how do i get the mice out before i do so
they don't die and stink in there. i know this is there entry based on
footprints in the snow and tunnels
13 Feb 2013, 14:15
We have had a mouse problem in our house for several years. We are pretty
sure they are getting into a crawl space underneath the house by first
getting under our deck that is against that wall. We have put very small
screen all around the deck, but to no avail. We think they may be coming up
on the deck and getting between the boards and going under it that way. Do
you have any suggestions? We've been told we can't seal all of the deck
spaces because it will cause the deck to puddle and mold.
Ask the Exterminator
13 Feb 2013, 14:22
You can use Xcluder ito fill the problem cracks. Xcluder, which is sold on
this website, is similar to steel wool, except the "steel" is stainless and
won't corrode when exposed to weather. It will allow air and moisture to
pass through, but not mice. You might want to discuss this with a deck
08 Apr 2013, 11:37
i cant get mice to stay out of the dressers in m house and they keep
eating up my clothes what is the best way to get them outof the dresser and
out of my house?
30 Jul 2013, 11:37
We installed new rubber stripping on our garage door (which is attached to
our house) and mice keep chewing through the rubber seal. We put steel
mesh at each corner and that stopped it for a while, but now they are
chewing through the middle of the strip. is there anything we can do to
prevent them from chewing through the rubber? Thanks.
28 Aug 2013, 12:13
We have mice entering our dryer vent and then that leads to our pantry. I
just saw one scurry under our couch. I have read that steel wool can be
used where the dryer vent tubing meets the exhaust hole in the wall. My
concern is that steel wool is a Great fire starter. Won't it potentially
catch our house on fire? That's one way to get rid of mice but I don't
want to get rid of us! Thanks!
Ask the Exterminator
28 Aug 2013, 13:59
As long as you are not blocking the air flow of the exhaust pipe, using
steel wool should be no problem. Personally, I prefer using Xcluder, as
mentioned in the article above. Xcluder is made of stainless steel wool so
it won't degrade over time.
30 Aug 2013, 17:40
Ok, so here's the situation. I recently moved in with my Father after he
went ill (terminally, maybe 6-8 months), to take care of him. My Mother has
already passed and after his diagnosis he sold his house to pay for medical
bills, etc. In our house growing up, I never seen one bug... literally. He
now rents a mobile home (it's newer), mainly due to it's what I can afford
(I'm a Teacher). After I moved in, I started to notice weird things, little
droppings in cabinents, my towels under the sink started to get holes, the
smell under sinks were old smelling, my computer wires had chew marks,
etc... anyhow, I had my ah-ha moment and understood that we had mice. Then,
one night I went into the kitchen and turned on a light and a mouse ran
right by me. I was so freaked out and literally stood on a chair for 3
hours crying hysterically. Shortly after, I tried to tackle the problem
after reading as much as I could on the web. I pulled everything out of
kitchen, cleaned with bleach, sealed every single opening I could find in
under counters, behind stove, fridge, dryer, washer, baths, etc, I packed
every non essential in plastic tubs and put down traps (any kind I could
get my hands on). I've caught 3 in a week. I then had a friend come and
look under the mobile home and see if he could see any access points, etc.
He said that there were "many" that could potentially be ways for the mice
(FIELD MICE) to be getting in and it also appeared that some holes had been
half-assed patched before we moved in. I asked the landlord to fix any
holes on the outside or under the mobile home however was told that it was
not the landlords responsibility. I know this is a long narrative... but as
a young female (who obviously is terrified) I don't know where to start on
the outside/under the house. The landlord suggested I leave the holes open
and put a "block" of lethal bait and let them die off. Then another friend
offered advice to seal any points outside first so that they don't die in
walls and/HVAC (where I believe they are). I contacted some exterminator
companies and was told that they only put out bait and do not seal access
points under or around outside of house. Do I then hire a contractor? Do
you have any idea how much it would cost to have someone seal possible
entry points? I figure I could do whats visable around the mobile home with
durable products. I am in no way going under the house. Is there anything
else I can do? Thank you for listening and/or giving any advice!
04 Sep 2013, 15:58
hot to keep mice out of the air conditioner unit outside?
06 Sep 2013, 09:46
My daughter lives in a first-floor apartment and she has problems with
mice. The apartment has heat/ac vents on the floor and we think that's
where the mice gain access to her apartment. Other tenants have problems
with mice as well. Since it's an apartment building and not a place she
owns, there is but so much she can do herself as far as sealing pipes,
etc., to keep the mice out. Is it safe to use the galvanized wire cloth to
secure over the floor vents, and what other options does she have? She's
using traps for any mice that may come in but she wants options to keep
them out in the first place. Any advice you can give will be greatly
appreciated. Thank you.
Ask the Exterminator
06 Sep 2013, 11:33
Galvanized wire cloth will certainly prevent mice from entering. However,
it does not stop the problem, as you well know. The landlord is obligated
to provide a pest free environment. It's the law.
08 Oct 2013, 19:38
I hear a mouse something in my a.c vent. I live in mobile home so vents are
on floor.Hoe can i trap it before i causes damage?
Ask the Exterminator
10 Oct 2013, 10:57
Try putting traps inside the floor vents. If you can find mouse droppings
or evidence of something the mouse is eating, place the traps near those
locations. Use lots of traps. Most homeowners put out one or two traps, but
if you put out a dozen traps you will speed the process.
14 May 2014, 00:35
I live in a townhome and have caught two mice within a week. I removed all
food off the open wall pantry, and have not seen any mice since, however I
swear I can hear them in the walls. My garage is not connected to the house
and the front door and back door are sealed very well. Could they be
getting in through the cracks? How many more are there? When will they
leave? I feel like I have done the standard things to not make them come.
I've set traps in the laundry room, by the pantry, under the couch, in the
water heater room, eat strictly at the table, and sweep the floor everytime
I see a crumb on the floor. What else should I do? I actually just saw a
mouse walk across the outside sidewalk close to the trash can by the garage
28 May 2014, 00:05
I have the same issue as @Cher. I just saw a mouse outside. I have an
exterminator that comes and he can't even find the openings. He puts down
dozens of traps. I have a small dog so we are careful on the type but he is
not stingy in putting down dozens. I have not seen the mouse or mice but I
see the droppings. Will the mouse enter and exit through the same hole? My
basement is sealed with concrete. Do I need to have it finished as in
sheetrock? Won't they just be in the walls and find another exit point?
11 Jun 2014, 14:04
I too live in a townhome.... I moved in late last fall only to find out
once winter moved in there was a mice problem and the previous owner knew
it. I should have guessed after finding out she had 3 cats. I'm connected
to four other townhomes of which my neighbors all say that they have them
but "haven't seen them recently". I hear mice constantly in my walls,
behind my kitchen appliances and find random mice poop in different areas
of my condo... not to mention smelling the dead ones in my wall and attic.
I just noticed poop in my upstairs guest bathroom closet. I've tried
EVERYTHING! Peppermint oil, ultra sonic plug ins for every outlet, several
types of mouse traps that the mice are not going for.. hired an
exterminator that dropped 3 poison traps and went on his way. I need to
remove the poison traps due to my dog and it being fatal if he were to eat
the mice poop or the mouse. I will lose about $20,000 if I am forced to
move.... I need any an all advice. Do I caulk in between the siding
Ask the Exterminator
11 Jun 2014, 14:20
Like the article says, Nancy, the first step is to find all the places
where the mice are getting inside. The article talks about all the
possibilities. The article also mentions a product called Xcluder. You
cannot buy this product in stores, but it's an inexpensive and easy to use
The mistake homeowners make is they put out too few traps. Sonic devices
are a joke and repellent odors like peppermint don't make mice pack up and
move outside. You must trap the mice. You need to put out two dozen traps
per townhome. The traps must be placed perpendicular and touching the
baseboards of walls. If done properly, you can trap all the mice in a day
or so. All the townhouses must do it at the same time. For more questions,
please use the "Ask the Exterminator" link at the top of the page. This box
is for "comments".
20 Jun 2014, 11:47
There is a big vent (like an exhaust pipe) underneath our stove that goes
to outside. Mice are all the time coming in through this vent from the
outside. What is a good way to block the mice from coming in?
Ask the Exterminator
23 Jun 2014, 18:03
Hardware cloth over the vent. Buy it Home Depot for under $10. It's kept
next to the chicken wire.
26 Jun 2014, 21:46
We found 2 mice in our kitchen sink the other morning. The only droppings
were in the sink -- nowhere on the floor or counters. We're assuming they
came up from the pipes since they couldn't jump high enough to get out of
the sink. We have a brand new home and we checked the cupboards and under
the sink for holes -- nothing. It's sealed real good.
Is there anything we can do to prevent them from coming up the pipes,
through our garbage disposal and into our sink?
15 Jul 2014, 01:39
Is it possible for mice to climb into a A/C drain pipe? I noticed water
damage on my ceiling, and by following my A/C drain system I found that
where the pipe drains out side my home something had shoved the opening
full of leaves and grass and other detritus to the point that the pipe was
clogged and wouldn't drain.
Does this sound like something mice would do? We've had them in our house
and can't find the entry hole. Also would a simple metal screen over the
pipe exit keep them from getting in?
15 Jul 2014, 12:12
I have mice coming into my drop ceiling in the basement. They always hang
out right above my head so it's very unpleasant when we set traps and in
the middle of the night you hear the poor mice suffering. Anyways, the mice
are coming in from under our backyard deck. The problem is that we can't
take apart our deck to find the exact holes where the mice are coming in.
We've set traps up everywhere in the ceilings and always catch them, but we
need to eliminate them from coming all together. It keeps me up at night! I
bought steel wool to lay around in the ceiling, but like I said I can't
find the hole where they're coming in so it may not even be useful.
Do you have any other suggestions for me?
Ask the Exterminator
16 Jul 2014, 09:13
You know the mice are getting inside via entry points under the deck. If
you hired a pest control professional, they would require you to open the
deck to allow access to the problem area. So, you can either suffer with
mice, or open the deck to fix the problem. Simple!
10 Aug 2014, 02:17
I have a covered porch with a funny angled corner. Every few days, there
are mouse droppings just in that corner. Any idea why? And how can I get
rid of them?
27 Aug 2014, 13:42
We have a stone foundation/basement, any tips on how to control mice
getting in under ground through the gaps in the old foundation? Is there
anything we can use as a deterrent in the basement?
10 Sep 2014, 12:36
Helllp! I see a large hole near my stove pipe and think this is allowing
access. I wonder, too, if there is one behind my fridge. Do exterms
arrange to pull out these appliances to plug the holes, or is it expected
that the apt owner should hire others to do so? SO FREAKED OUT. Thanks
for your help
16 Sep 2014, 21:24
I have mice in my condo, a lot of others in the bldg also have mice except
those with cats. Is it safe to use steel wool to plug around the holes
where the pipes come into the unit for hot water heating systems.. Can I
remove the covers of the baseboard heaters safely so as to see the holes
There is also a 3/4 inch gap under the door to the unit that I will try
putting on a door sweep..
Exterminator placed posionous black boxes in the condo and bldg. They don't
seem to have helped...
Ask the Exterminator
22 Sep 2014, 15:55
Mouse control starts with closing the exterior access points. Replace door
thresholds where required. Steel wool is okay, but it rusts and rots when
exposed to rain. Instead, use Xcluder. It's just like steel wool, but the
"steel" is stainless and it won't go bad.
As long as the electric is turned off at the power panel you can open
13 Oct 2014, 21:39
I just give some advise....Feed the mouse with oatmeal, salt (a lot)and
some cheese flavor ,,the mouse go eat and go be thirsty, so , they go look
for water ( leave some the far you can from home) they go find it and after
eat they go explode.
03 Nov 2014, 18:19
We have mice getting in under our fireplace and entering our basement. I
have found the hole where they enter and fixed it. Outside under our
fireplace is dirt, what can I put under there to help keep the mice away?
Ask the Exterminator
04 Nov 2014, 09:42
Xcluder carries a product that you can lay down in sheets. Mice cannot
burrow or chew through it. Go to their website.