How to Repair a Crack in a Concrete Floor
LESLIE: Ray in North Carolina is on the – on the floor, I was going to say.
RAY: You sound like me today.
LESLIE: Sorry, Ray. I’m reading what your question is about and I introduce you as “Ray is calling in from the floor.”
No, we’ve got Ray from North Carolina on the phone who’s got a crack in the garage floor. Tell us what’s going on there.
RAY: Unbelievable. We’ve got a very small – not unbelievable but had a very small crack since we moved in, which is back in 1996, and it never really moved. And we had a little earthquake here. I don’t know if you heard about it but it was a small, little earthquake that – the one that affected the Washington Monument and all that.
RAY: But it did drag down here. But anyway, I don’t know if it’s really related to that or not but there are no cars in the garage because I’ve had too much junk, unfortunately.
LESLIE: Join the club.
RAY: But now the crack is now about a ¼-inch to, in a couple of spots, almost a ½-inch wide. And it goes from one end to the other. We’re talking about 17 feet. I don’t know what to do.
TOM: Well, first of all, the concrete floor is not structural in the sense that it’s not helping to hold up the building, in most cases.
LESLIE: And essentially, it’s right over dirt.
TOM: Yeah. Think of it as a very stiff type of flooring because that’s basically what it is.
TOM: Now, to fix that crack – you’re never going to make it go away but what you can do is seal it. And when you seal it, you stop moisture from getting in there: water that runs off the car, for example, in the wintertime. That could freeze and cause it move more quickly.
So, there’s a couple of products out there that will do this. I would take a look at a very basic and effective product called QUIKRETE Concrete Repair. Basically, it’s a crack sealer that’s in a tube, like a caulking tube.
TOM: And you cut the tip off, you try to keep it to about an 1/8-inch, if it’s a ¼-inch crack. You can fill that crack from one end to the other, let it dry. And then you could put a concrete floor paint on top of that. And so that will make it very difficult for you to see, especially if you paint the floor and you use one of the products that has sort of a color chip in it. Gives it a little bit of a pattern and makes it harder to see; it’s not quite as obvious.
So, I would simply fill it, paint it and call it a day.
RAY: Very good. Yeah, it actually is painted now. Let me ask you this. The only other problem I’ve had in the past, real quickly, is that when I have tried to fill it, if I wait too long, it’s too high. And obviously, it’s very hard to sand down flat or level. Is this a self-leveling product? Can I just grind it down with a grinder?
TOM: Well, it’s not going to be stiff like concrete. It’s a sealer, OK? I mean it’s a repair product, so it doesn’t – it’s not hard like concrete.
RAY: OK. I’ve got you.
TOM: But you basically want to put it in so it sits just below the surface.
Now, a little trick of the trade is if you have a really deep crack, you can sort of stuff the crack first with a backer rod or some other type of product like that so that the repair material stays up towards the surface.
RAY: Mm-hmm. OK.
TOM: They have another product called a “self-leveling, polyurethane sealant.” And with that, it will definitely flow nice and even.
RAY: Excellent. Well, I appreciate your help very much and I enjoy your show.
TOM: You’re very welcome. Thanks so much for calling us at 888-MONEY-PIT.