Cracks in Concrete Foundation: Assessing and Containing
LESLIE: Alan in Idaho is on the line with a crack in a foundation. Tell us what’s going on at your money pit.
ALAN: You know, when I first bought the house, a contractor buddy of mine said it was no big deal and he gave me some epoxy. Said to drill some holes in it and squirt it in there until it mushed out all the way through and then just go and smooth it off. Well, I didn’t seal it but it’s cracked right again beside it.
TOM: OK. So you have a crack in the foundation that you filled with epoxy and it’s continuing to crack. Is that the case?
TOM: How old is your house?
ALAN: 1967 is when it was built.
TOM: Alright. So it’s concrete-block wall or cinderblock wall, correct?
ALAN: It’s concrete.
TOM: Now, do you have any drainage issues around the house?
ALAN: Not that I know of.
TOM: Have you had any moisture in the basement or signs of that?
ALAN: The only time I’ve ever had any moisture in the basement is a previous owner drilled a hole in the floor and ran the condensate drain through the air conditioner into the floor.
TOM: Alright. That’s not the kind of moisture we’re concerned about. The reason I asked that question is because it sounds like your wall is a little unstable and that’s continuing to move. And the first thing to do when that happens – if it’s not a serious crack, not one where the wall is being displaced – is to make sure that your grading and your drainage conditions are absolutely letter-perfect. Because the more water that soaks around the outside of that house, the more water that comes off gutters and gets discharged against the wall, the weaker that foundation gets.
It’s kind of like this: when it’s rainy and you walk across a field, you sink into the mud because wet dirt is not as strong as dry dirt. So we want to try to keep the dirt around your house – and specifically, under your footing – as dry as possible. So drainage control is important.
Now, beyond that, if this is just sort of a hairline crack that’s forming – is that what we’re talking about here?
ALAN: Yeah, yeah, it is. Well, the original one was a pretty good-sized crack but …
TOM: Well, what I would do if it’s a hairline crack is I would fill it with silicone caulk, because it will expand and contract and won’t – epoxy is pretty stiff if it’s going to break and crack through it. So I would just fill it with silicone caulk; that will just keep out some moisture and drafts from coming through it.
ALAN: Alright. And now, if I dig down – I know it doesn’t go clear to the footing because I’ve been down that far. I dug down to see how far it went down. And so, dig down and suggest maybe tarring it up below grade?
TOM: I wouldn’t go through all that. I mean right now, it’s – I would just improve the drainage conditions and seal the crack from the inside where you can.
TOM: Alright? I don’t think it’s going to really add to it to tar up the whole foundation. You don’t seem to have any major moisture problem here, so we’re just trying to deal with the drafts and any potential leakage in the future.
Good luck. Thanks so much for calling us at 888-MONEY-PIT.