Installing a Curtain Drain Can Keep A Basement Dry

LESLIE: Dion in Iowa is dealing with some sort of crazy situation in the basement. What’s going on? You got a lot of water in there?

DION: Yes, we live on a slope and the contours out in the yard, they pretty much funnel everything towards the house. I’ve got a good idea on what to do on the outside of the house but I want to finish my basement and I don’t quite know what to do on the inside to battle this mold off to where I don’t have to worry about it being inside the wall after I finish it off.

TOM: Mm-hmm. Well, on the outside is where I would start and, typically, if you have a hillside that points down toward your house, you want to intercept the water as it runs down the hill with something called a curtain drain. Are you familiar with this?

DION: That’s something like, say, a sub-drain?

TOM: It’s like a trench. And basically, you dig this trench …

LESLIE: It’s a moat, in this situation. (chuckles)

TOM: Yeah, it’s a moat. That’s a good point. It’s a very shallow, small moat about 12×12. So, you basically shovel out this narrow ditch and you put in a perforated pipe – so like a four-inch PVC pipe with holes in it – and then you surround that with stone. You put a little bit of weed cloth and then dirt and grass over it so when it’s done it’s invisible. But as the water runs down the hill, it falls into the curtain drain and then it comes up into the pipe and then runs off somewhere, wherever you point it.

DION: Would you want to horseshoe it around the house more or less? And outlet it on the sides and …

TOM: (overlapping voices) Yeah, right. That’s right. Exactly. And shoot it off – right, shoot it off to the sides where it’s not going to do any harm. That’s one way to intercept that water run off. I mean the other way is to create something called a swale, which is what should have been done, but it’s very hard to do at this point when the house isn’t new. And a swale is simply a way of grading soil away from the house walls and then the hillside grows into that or grades into that and then it collects that water, runs it around the house. But that’s a lot more complicated from a grading perspective. A curtain drain is pretty straightforward. It’s a couple of days of work but it works really well.

LESLIE: And does a landscaper do that?

TOM: Yeah. But I mean – well, I wouldn’t hire a landscaper that was the first time he ever built one.

LESLIE: Right.

TOM: They’re not that hard to do. You need about 1/8 to 1/4-inch-per-foot slope.