We moved into our house about 1.5 years ago and are having a problem with mice getting in. We think they are coming in through the grates that lead to the crawl spaced under our house. The crawl space is open to the partial basement, so the critters would have no trouble getting into the house once they are in the crawl space. The house was built around 1930, and we have no idea why these grates exist. Would there be any problem with covering them or boarding them up some how? We have a modern gas furnace. The grates may be part of the old coal storage area from when the house had a coal furnace, but this is a guess. Any ideas to why they are there and if it will cause a problem if we cover them?
Don’t board them up, just nail hardware cloth over them. Crawl spaces need air circulation, otherwise they get nasty.
I confess that I have never heard of hardware cloth. <googles hardware cloth> What would be a sufficient gauge to keep the mice from chewing through it?
hardware cloth (whatever is sold) will stop mice. window screen in addition will stop insects, which might nest in there.
window screen might need to be cleaned of seeds and debris periodically.
Mice don’t chew through wire, generally. But I’d get galvanized, it would probably hold up better over time (take longer to rust). Just my homeownery opinion.
Are you talking about a vent as seen here:
Or do you mean some sort of big iron grate for loading coal?
If you mean the foundation vents, closing them is a matter of debate. In some conditions they worsen the problems they are meant to address (moisture).
Normally vents include a wire screen that would keep out insects and other vermin. If yours lack this, you could replace the vents or add some screen to the inside. You can buy rolls of window screen at hardware stores.
Make sure there’s no one in there first.
The grates are basically what you’ve show in the picture, just bigger and older. My guess is that they are original to the house built in 1930. But there is only a grate there isn’t any mesh or screen to keep the mice out. We will likely do as advised and buy some hardware fabric to put behind the grate.
The dirt (ground) in the crawl space is covered by a plastic tarp as part of our radon abatement system, so I don’t know if moisture would be an issue. There is a pipe that goes under the plastic tarp and a fan that pumps the air from under the tarp to the outside of the house.
Anyway, thanks for all the advice. Do you think the hardware fabric will also help to keep the bats out of the house? Assuming we can figure out where they are getting in?
There are different sizes of hardware cloth, get 1/4 inch to keep mice out, 1/2 inch is too big. I would back that with screen also to keep bugs out. Mice can chew through screen so you do need both.
The same size should keep bats out if that’s their way in. I would also look higher for bat entrance points. Make sure there’s something over the chimney, check your gable vents or any other roof venting. Go in your attic during the day with the lights out and you might see where they’re getting in.
that will keep bats out.
best is a one way bat door, so they can exit but not enter. two pieces of hardware cloth tacked on each side of the hole(s), with the free ends meeting and peaked in the middle. when you are sure they are gone (like if when they might migrate to a warmer climate in fall) then you could tack it permanently over the hole.
consider putting up a bat house if you have a few regular bat residents. they do come back to the same location in the next year. they eat hundreds of mosquitoes every night. bat house plans are all over the net; are simple; can mount on the side of the house (out of sun) or on pole or tree).
Had another bat last night. That’s two this week. We have a wild life removal guy coming out tonight to put in a one-way bat door. Keep your fingers crossed!