How to Add Proper Drainage Behind a Retaining Wall
LESLIE: Terry in Tennessee needs some help with a retaining-wall problem. Tell us what’s going on at your money pit.
TERRY: Yes. I have a leak problem from a drain on my back end of my house. I have a full basement and it’s heated and cool but I use it as a garage/work area, et cetera. From my garage, there’s a retainer wall that goes past the end of my drive? It’s about 20 yards long. I have two drainpipes at the bottom of that.
And when it rains, well, mud is coming out, so undoubtedly it’s stopped up. And I’m hoping that you can give me the name of some apparatus without digging out the whole entire back of the retainer wall.
TOM: So the mud gets from behind the retainer wall and then comes out the bottom of it on the low side and what? Runs down your driveway or something?
TERRY: Yeah, the retainer wall is right at the end of my driveway, coming up from the street to the end of the house.
TOM: So, the solution here would have been in the way the retaining wall was built to begin with. Because behind the retaining wall, it sounds like there’s a lot of dirt sort of pressed right up against it. The way to build this is dig down around the retaining wall, probably about 2 feet behind it. And then you’re going to have stone that is about 12 inches away from the retaining wall. Behind that, you’d have filter cloth and then behind that, you’d have soil. I’m talking vertically now.
So, up against the retaining wall, you have stone. Right behind the stone, you have filter cloth. Right behind that, you have the soil. And so, if you don’t have something like that and you’re getting a lot of dirt that’s just basically turning into mud and running through the wall, then that’s going to happen.
Now, I guess your question is: is it really worth it to regrade the area behind the retaining wall to put in the proper type of drainage stone and so on? Or do you just put up with cleaning your driveway every once in a while? I mean for me, if I bought into a house that was like that, I’d probably clean the driveway every once in a while.
TERRY: Yeah. Well, it’s almost a constant thing when it rains. But when the drainpipe – of course, it was put all the way around the house: the proper drainage factor, like the drainage pipe; the gravel over the pipe; the cover over that. So it was all done that way, as far as having that done.
TERRY: It’s just, over time, it’s – the house is 17 years old. Well, it started to leak and some way or another, it filtered down into the drainpipe, which drains past my driveway or it did at one time, anyway.
TOM: Well, you could always rerun those downspouts so that they’re not discharging that close to the house and keep them well away. That could help you a bit, as well. But it really comes down to how that soil is put together behind the wall, if that makes sense to you.
TERRY: OK. OK. Well, that was my question and I thank you so much for your help.
TOM: You’re welcome. Good luck with that project. Thanks so much for calling us in 888-MONEY-PIT.