Repair a Crack in a Concrete Slab Floor
LESLIE: Casey in Louisiana listens to The Money Pit on KEEL and you’ve got a foundation question. What can we do for you?
CASEY: Well, I have a 43-year-old house and it’s got a foundation across … it’s got a crack across the entire foundation.
LESLIE: What direction does the crack run in?
CASEY: What direction? It runs from east-to-west. (chuckling) It runs across the body of the house.
TOM: It’s a horizontal crack?
CASEY: And it varies a little bit; it’s not exactly in a straight line but fairly close.
LESLIE: And how big is this crack? Is it fairly wide? Fairly deep? Describe it a little bit.
CASEY: Well, where we can see it – because there’s linoleum that’s on the floor; sheet linoleum – it’s separating some of the linoleum. It’s not, probably, but about four or five inches deep, at the most, that I can tell. And it’s not very wide. But it’s gotten a little wider in the eight years that we’ve been in the house.
TOM: Okay. So the crack is in the floor and it kind of goes in and out from under the linoleum? Is that the situation?
CASEY: And we can feel it under the linoleum. There’s some difference in … the height difference from one side to the other, but nothing significant.
TOM: And this is a basement or the first floor?
CASEY: We only have a one-floor home.
TOM: Okay, so it’s a slab on grade home.
TOM: Alright. Well, concrete slabs crack.
TOM: Sometimes … some would say that’s what their designed to do. Usually it happens because of shrinkage. Really two reasons; either shrinkage when the initial pour …
LESLIE: Well, it could be ground settling, couldn’t it?
TOM: Or it could be some movement of the soil.
CASEY: We have very clay soil here.
TOM: Well …
CASEY: It moves horribly.
TOM: Yeah. I was going to say the best advice we can give you is to try to keep that soil as stable as possible and that comes back to moisture management; making sure that the water around your house is draining away from the house and the gutter system‘s extended out so you keep the soil as dry as you can.
Do you have any evidence that this crack is active? Or is it something that’s sort of always been there?
CASEY: It’s been here since we moved in. And I couldn’t … it was my … my husband’s grandfather built the house …
CASEY … himself and it was here when we got here and there’s no evidence that it’s like getting wider all the time.
TOM: Alright, well that’s good news. Then, I would tell you not to worry about it. If you ever decide to replace that floor and you have it up, I would fill the crack with a flowable urethane, which is a flexible caulk kind of material that will seal it in really good and stop any soil gases from coming through there. And you can build it up a little bit and not feel it, now, when you walk over the new floor.
TOM: But in terms of structure, if it’s been there all this time and you see no evidence of it moving, then I wouldn’t worry about it.
CASEY: Okay. Well, here’s my question; my bottom line question. Because we would want to … we would want to fill it and replace the flooring. We’ll eventually move from this house; we know we will. And how do you sell a house with a crack in the foundation? Because, obviously, it’s done. But people have said, “Oh, no, you’re going to have to get the foundation fixed.”
TOM: Well, if it’s … if it’s the floor, it may not be the foundation. You may be confusing the two parts of your house. It depends on how the floor was poured. Now, sometimes you build a house with, say, a footing and then a concrete block wall that comes up and then the wall is on top of that. And then the floor is, basically, floating and it goes in between those walls. In any event, most of the floor surface is not load-bearing; it’s only load-bearing under the walls itself. So it’s not, technically, the foundation that’s cracked; it’s really just the concrete floor that’s cracked.
There are two ways to handle it. You know, if you want to be incredibly honest with the people that are buying your house, you can tell them that there was a crack under the floor and that it’s been there since your grandfather – your husband’s grandfather – built the house and it’s never moved, you’ve sealed it properly and you refloored over it. If it’s something that they’re concerned about, they could have a professional home inspector or an engineer evaluate that.
The other thing that you could do is, if you really just want to put your fears to rest, is have that done right now. Have an engineer look at it and provide a report for you identifying the condition, recommending any repairs. And then get those repairs done, have them reinspect it. And that kind of creates what Leslie and I like to call a pedigree on the repairs so that we know that it was done correctly. Then you pass that along to any future owner and …
LESLIE: Yeah, and it’s a level of reassurance, to that future owner, that you’ve done something properly and you’ve got all the paperwork to back it up.
CASEY: I really don’t know – because this is our first home that we’ve ever owned. And I would want to sell it so that they would know and that it was … that it was fixed properly. What kind of – and this is another thing I don’t know – what kind of cost does that run into? Or do you know?
TOM: Well, it really depends on what’s wrong. You want to start with the inspection itself. And the inspection’s probably going to cost you two or three hundred bucks for an inspection and report. And then, from there, you can decide what your best option is. I mean it may be that the engineer comes out and says, “I don’t see any reason to repair this other than just sealing it,” like we’ve suggested; and you’re done. But if there is a repair that’s suggested, then you could evaluate your options.
In any event, if you want to put your mind at ease, have a design professional – like an engineer or an architect – review that crack and determine whether or not it’s of structural concern. And then, move on from there. Okay?
CASEY: Excellent. Thank you very much.
TOM: You’re welcome. Thanks so much for calling us at 1-888-MONEY-PIT.