How to Fill a Void Under a Concrete Driveway

LESLIE: Now we’re heading on over to Mike in North Carolina who’s got a driveway question. Drive it on over. What can we do for you, bud?

MIKE: I had put in a new plant – or got ready to put a new plant in front of the house. And when I took the old one out, there was a crack in the foundation and also a pretty good-sized void underneath the driveway. And I’ve had three different companies out to take a look at it and after all that, I don’t quite know what to do.

TOM: OK. So this crack is in your foundation? It’s on your basement wall? Where are you seeing it – or on the outside wall? Describe it.

MIKE: It’s on the outside wall in the corner of the garage.

TOM: Alright. And you’ve got a driveway near there where the driveway is sunken in a bit? It sounds to me like you’ve got a water problem where water is collecting in that area. May have undermined some of the soil. Small cracks – is it vertical cracks – small vertical cracks are what it is?

MIKE: Vertical crack, yes.

TOM: Yeah. It’s a very minor, very almost commonplace kind of a crack, so I wouldn’t get too terribly worked up about it. You’d be surprised how many cracks foundations have. We see them all the time. So, I wouldn’t panic about it. But if you’ve got an area that’s sunken in where the driveway is, what you are going to have to do is cut that driveway out, fill that area in, tamp it down, pack it properly and have the driveway restored in that particular area.

MIKE: The driveway hasn’t sunk yet. It’s just where it always has been.

TOM: Well, when you just said before – when you said before that there was an area that was sunken in, you did not mean the driveway? What’s sunken in?

MIKE: No, no. Actually, there’s a void underneath the driveway. You can see where the driveway pad comes up to the garage – when I took this plant out, you can see a void underneath the driveway.

TOM: OK. So the void’s under the apron, is what you’re saying.

MIKE: Correct, yes.

TOM: It’s under – OK. Alright. Same advice. You’ve got to fill the void in or the driveway will drop into that spot, OK? And water will continue to collect there and it’ll wash out what’s left of the footing around there – the soil under the footing – then you get more shifting. So, you’ve got to restore that soil.

Not unusual, because a lot of times you get organic matter that gets in there. It could be, I don’t know, wood. It could be paper. It could be anything that was accumulating there from when the foundation was dug. And then it rots away and the voids form and the water gets in there and it’s kind of a vicious cycle. So you need to get that repacked with soil properly and then regraded to slope away and then restore the driveway.

So I don’t think you have a big problem there. I think you have sort of a medium-sized maintenance problem but you should do it, because it can get worse if you ignore it.

MIKE: Yeah, OK.

TOM: Thanks so much for calling us at 888-MONEY-PIT.