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Cracks in Concrete Floors

  • Transcript

    LESLIE: Sam in California just bought a house and found something you didn’t quite expect to be there. Tell us about it, Sam.

    SAM: There was a … I removed a carpet and there was a crack, in the living room, in the slab.

    TOM: The old carpet-covering-the-crack trick. (laughing)

    SAM: Yes. Yes. And I didn’t know what the best remedy is for it but what I did was just fill it up with foam and put a little bit of … like a layer of concrete on top of it. Just like a thin layer.

    TOM: Well, let’s talk about what the crack looked like, Sam. When you pulled the carpet up, was it very wide and was it very deep? Explain it to us.

    SAM: It was about half an inch at the widest point.

    TOM: Okay.

    SAM: And it started from the fireplace all the way … almost to the other side of the house (inaudible).

    TOM: Okay. How old is your house, Sam?

    SAM: It’s thirteen years old.

    TOM: Okay. Well, with that age house, I wouldn’t be terribly concerned about it. I’m suspecting that it was, most likely, a shrinkage crack. It could have been there for a very long time. Sealing it up is a good idea. It really is just to stop any moisture or dirt from getting up through there, any soil gas …

    LESLIE: And causing any further damage.

    TOM: Yeah. It probably is a fairly static situation and it probably won’t get any worse. So what you did was the right thing. I will caution you, though. You said that you sealed it and then you put concrete on top. The concrete you put on top, unless it happened to be an epoxy patching compound, probably won’t stick. Because just using a simple concrete mix – or cement mix, I should say – or mortar mix on top of an existing slab does not have enough adhesion for it to stick. And that might crack and chip off. But that wouldn’t be indicative of movement in the slab. That’s just kind of that that’s just not going to work. But as long as it’s smooth, now – and, I presume, you’ve re-carpeted that area.

    SAM: I put laminate floor on top of it.

    TOM: Oh, you put laminate floor. Well, then, that’s fine. As long as it’s smooth like that, then it should be okay. If you see any other evidence of structural movement – like a crack in the wall or something of that nature – then we need to have another conversation. But one static crack like that is fairly common. And the fact that you found it under the carpet is not the least bit unusual. Obviously, that’s not something you can do when you buy a house; it’s something you do after you own the house. But whether or not it was covered on purpose or not we don’t know; but the fact that it was there doesn’t give me a lot of concern at this point in time.

    SAM: Yeah, the carpet wasn’t wet or anything like that. It was in okay condition, I guess, so …

    TOM: Yeah, probably just a shrinkage crack. Okay, Sam?

    SAM: Thank you very much, guys. I enjoy your show very much.

    LESLIE: Thanks, Sam.

    TOM: Thank you for calling us at 1-888-MONEY-PIT. 888-666-3974.

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