How to Seal a Foundation Wall to Prevent Mice from Entering
LESLIE: Ron in Pennsylvania, you’ve got The Money Pit. What can we do for you today?
RON: I have an 1865 farmhouse that is in very good condition, with about 2-foot-thick stone walls that are the basement walls. And from what I understand, those old, stone walls are made, basically, of stone and sometimes they put rubble in the middle. Somehow, field mice have found their way through from the outside and I’m trying to figure how to maybe parge or put cement in between the stones to protect that from happening.
TOM: So, the mice, you think, are coming right through the foundation wall?
RON: Oh, yeah. They’re finding their way through. It’s been 150 years.
TOM: Why can’t you point the openings up? By pointing I mean add mortar to those cracks or those crevices in the foundation wall, to try to seal those gaps up?
RON: My biggest question, I guess, is: how do I get that part cleaned out so that I can point that up? I guess I should use air rather than water to try to blast it out, to get the dust out of there so that the moisture would – so that the whatever cement I use will adhere. Would you recommend water or air to try to clean that?
TOM: I think you could probably do it with a pressure washer but you’re just going to have to make sure it dries really well, you know, before you go ahead and point it up.
RON: Is there any particular type of concrete product you would recommend or cement you would recommend for that?
TOM: I would take a look at the products that are made by QUIKRETE – Q-U-I-K-R-E-T-E. And you can find a mortar patching compound that QUIKRETE makes and use that. Because it usually has sort of a stickier component to it, so it’s easier to press it in those places.
But listen, aside from just sealing up those gaps, just keep in mind that there’s a lot of different places that mice can get into your house. It might not just be those gaps in the foundation. They only need the space of about the width of a nickel to squeeze through.
RON: It’s amazing – pretty amazing – how easily they can get in. We don’t have a lot of trouble with them now as we did a little bit earlier. But I’d like to try to make those walls nicer again. They have the old horse-hair glass.
TOM: Yeah. Well, of course, and that will basically handle both of those challenges. Generally, you want to avoid doing anything around your house that could be a nesting site. So that could be stacks of firewood or newspapers or things like that. You want to make sure you’re careful with food in the house, especially pet food or types of food products that you keep on the ground, where it’s accessible. You want to make sure those things are in sealed containers.
You want to look for all those gaps. If you find any little gaps like that, another little trick of the trade, just temporarily, is just to put steel wool in there. Because mice can’t get through steel wool.
And then you want to use rodenticides. You want to be careful if you have pets. If you do, there are bait stations that the bait can be held by that pets can’t get into. But keeping those in and around the interior perimeter of the home, especially if it’s up on a basement or a crawlspace, are effective, as well.
RON: Yeah. Alright.
TOM: Alright. Good luck with that project, Ron. Thanks so much for calling us at 888-MONEY-PIT.