Mouse Proofing Questions

April 6, 2020 8:31 AM

Looking for strategies to mouse proof an old house, with lots of tiny holes for them to travel through.

Hi all, we've been plagued with mice for a while, and we're trying everything short of getting cats to be rid of them. We've gotten better at food storage, and making sure that the dogs' food is away at night. We've been cleaning up areas that have gotten cluttered to reduce hiding spots. We're trying to plug up holes where they travel.

I have questions about specific spots in the house that are harder to deal with. First, what's the safest way to plug the holes around heating pipes? We've got hot water baseboard heat throughout the house, with copper pipes coming through the floors and walls. Can we use spray foam or steel wool, or are we running a risk of combustion.

Second, how to people deal with spaces underneath appliances? I moved my fridge away from the wall, and found a classic mouse hole in the sheetrock behind it, as well as tons of droppings. I know that they also go under the stove and the dishwasher. I could move the stove to clean behind it, but I don't think I can move the dishwasher. Any suggestions?

Finally, how do you deal with areas that are essentially inaccessible? We have a wood stove insert in our fireplace, and the mice have been hanging out behind it. I've put traps nearby, which only occasionally work, and sprayed peppermint oil back there, but I'd love a more thorough solution.

Thank you in advance!

posted by SobaFett to Home & Garden (12 answers total)

Around pipes, I've had great success with a combination of fine steel wool and spackle. Goosh the spackle into the steel wool, shove it into the hole, and then apply more spackle over top of it. This has worked for me where steel wool alone failed, and is much easier to control than spray foam.
posted by showbiz_liz at 8:47 AM on April 6, 2020 [1 favorite]

Also you should be able to move your dishwasher. Mine was secured in place with a tiny bracket that I just unscrewed.
posted by showbiz_liz at 8:48 AM on April 6, 2020 [1 favorite]

We did not have success keeping mice out until we focused on the exterior. There seemed to be a space between our foundation and house all the way around. We used concrete to fill the gap all around the perimeter and did not get any mice after that. YMMV, of course.

Good luck. They are very annoying to deal with!
posted by bruinfan at 9:38 AM on April 6, 2020

Response by poster: showbiz_liz, spackle is a great idea! I'll try that with the next round of steel wool.

bruinfan, I haven't looked at the outside of the house yet. Now that the weather is better, I'll need to see what gaps I can find.

Thanks to both of you!
posted by SobaFett at 9:55 AM on April 6, 2020 [2 favorites]

Can we use spray foam or steel wool, or are we running a risk of combustion.

Spray foams are available specifically to block rodents (Great Stuff, Dap, Tomcat). They can be safely used around even steam pipes.

You should avoid putting steel wool against copper pipes as galvanic corrosion can damage the copper pipe.

RE: mouse traps. Some traps are much better than other's even of a particular style. When I've had to live places with a mouse problem I've had the best luck with Victor snap traps with the plastic trigger. While designed/priced to be disposable I reuse the same traps repeatedly; I only throw them out if they get get gory.

If you have lots of mice the traps you construct with a bucket and roller or hinge work really well but you have to deal with either a bucket of live mice or a bucket of drowned mice.

If you seal the holes where plumbing comes into the dishwasher cavity it won't be a transit point. It should be possible to pull the D/W out with the removal of a few screws. Some people don't leave enough length in the supply and drain hoses or electrical connection to pull the D/W out though so be careful when sliding it out.
posted by Mitheral at 10:14 AM on April 6, 2020 [2 favorites]

Seconding emphasis on outside. We had professionals rat-proof a house in Austin TX (a wonderland for rats), and I was a bit surprised that they spent 100% of their effort sealing the exterior. It worked. They used screws, staples and fine hardware cloth to close the gaps, and recommended steel wool with a binder for very small gaps.
posted by SaltySalticid at 11:10 AM on April 6, 2020

As a kid, I spent summers in a house on an island. Seasonal homes are total mouse paradises, as you may know. We always brought the cat with us and for weeks at the beginning of every summer she would leave us tails, noses, internal organs, etc., while she taught them to stay outside. My advice is, why are you waiting to get a cat?
posted by Lawn Beaver at 12:13 PM on April 6, 2020

Response by poster: Lawn Beaver, the biggest reason we don't have a cat is allergies, mine and my wife's. Secondary reason is our two dogs, who would probably be fine with a kitten or two, but less thrilled about a full grown cat moving in.
posted by SobaFett at 12:30 PM on April 6, 2020 [1 favorite]

Counterpoint -- I have TWO cats and a significant mouse infestation that I had to call professionals to deal with. The mice were eating the hippie wheat-based cat litter, even, and hanging out IN the cats' litter boxes. So do not assume that cats will solve this problem!

The rodent control people used spray foam around the pipes, including the hot water pipes, and mesh and foam in other spots. There has still been some evidence of mouse activity (droppings, mostly) but it's been a lot less.
posted by gingerbeer at 5:26 PM on April 6, 2020 [1 favorite]

Unpleasant though it is, we have had success with baits, in addition to interior traps near known mouse runways, cleaning so we can see if it's old poop or new poop, lifting everything off the ground that isn't furniture, and blocking of holes we are able to access.

But yeah, baits in our roof space have had the biggest effect.
posted by freethefeet at 6:10 PM on April 6, 2020

If you prefer dogs to cats, get a Jack Russell. They're cute high-energy little dogs & they very much like to catch a mouse.
posted by rd45 at 1:05 AM on April 7, 2020

Traps traps traps traps. As you are no doubt aware, poison baits are out since you have dogs (I also have dogs) and the risk of one of them getting hold of a poisoned mouse is too great. But snap traps or electrocution traps are fine. You need way more than you think. Put them along the edge of the walls - they run along the edges. Put three or four on every single wall. Put five under the stove. You will catch them if you have enough traps. Do all this as well as sealing all the holes and eventually you'll get rid of them. Remember, if you think you only have one mouse you have like five. And even if you genuinely only have one mouse, you'll have thirty really quickly. So trap them like crazy as well as sealing everything up.
posted by mygothlaundry at 12:50 PM on April 7, 2020