LESLIE: Debbie in Ontario is on the line and has a question about cracks in concrete patio slabs. What’s going on?
DEBBIE: My question is to do with concrete – is that we had a cement porch and patio attached to the back of the house.
DEBBIE: We had to have a large portion of that – the porch, for sure, and a large portion of the patio – removed because we had around our foundation dug. New cement was poured. The porch first and then the patio was replaced. What happened is within about four days or so, it – they did the cuts the next day after the pour. But a few more days after that, we noticed two cracks came in the two cement pads that butt up against the porch. And left and right side, the crack goes diagonally across the pad.
We’re kind of wondering – the contractor saw what happened and he’s sick about it. And we were just wondering if there’s anything that can be done without having to remove those two large pads of cement, that attach to the house, and go through all that jackhammering and all that again.
TOM: So these pads, is this like a stoop that – you say they lead up to the porch? Are these parts of sort of the sidewalk?
DEBBIE: The patio – and then the porch is the only thing that’s higher than the patio. So, the patio is level with the cement driveway.
TOM: OK. Mm-hmm.
DEBBIE: And then the porch is up from that. So it’s on the patio itself.
TOM: And that’s where the crack is? Through the patio?
DEBBIE: Yeah, the patio. So the two cement slabs that are on either side of the porch. And the cuts that were made in the cement come up to the corner – the outside corner – of the porch on either side. But then you know how they can’t cut right up to …?
TOM: Right. But these are – OK. So you’re talking about a patio and you’re talking about two cement slabs that are opposite ends of the porch. So, I’m having a real hard time – as I’m sure others listening are, too – trying to figure out what this is all about. But it sounds to me like you’ve got slab-on-grade sections, right, and you’re calling that a “patio” or a “pad.”
DEBBIE: Mm-hmm. Mm-hmm. Correct. Correct.
TOM: Then you have the porch section. The porch seems to be fine. Is that correct?
TOM: OK. So, I would think that the soil underneath the patio areas would need to be especially well compacted before those slabs were poured. Because considering the amount of demolition that had to have happened, I suspect that that soil outside the porch area would not have been compacted. And that would have been really key to make sure you don’t get cracks in concrete patio slabs. The reason that they’re cracking is probably because there is some compaction that happened, based on the weight of the concrete and the drying and such. And that’s why they’re cracking now.
Now, can you do anything about cracks in concrete patio slabs? Well, whatever you do about it is going to be cosmetic, not structural. Also, if that concrete was not reinforced, that’s another reason that it would crack. There’s ways to put concrete in that’s just plain concrete and then there’s other ways that you could do it where it’s reinforced. So if it wasn’t reinforced correctly, that could be another issue.
But there’s nothing that you can do to repair cracks in concrete patio slabs, structurally, at this point. You’re always going to have cracks in concrete patio slabs. So, what you could do is seal that crack with a special caulk-like – it’s not caulk but it’s a caulk-like product that’s designed to seal concrete. But you’re always going to be looking at that crack unless you resurface the whole patio section. And again, there are products that are designed specifically for that, that will stick to the old concrete slab – which is actually pretty new, in your case – and perhaps cover the crack.
But that crack’s always going to be sort of a place where the patio decides to expand and contract with the seasons. So I do suspect you’ll always see some part of it. So, you either live with it and repair it cosmetically or just have it torn out and repoured. I mean a slab itself is not that big of a deal to get out, even though it seems like a big deal. But frankly, they break up pretty quickly.
And then, again, key is making sure that that base is properly compacted and properly tamped and that the slab is properly reinforced. If that’s done right, with the right concrete mix, this should not have happened.
DEBBIE: OK. Would it be alright, even, just to replace – like cut out maybe 2 feet along that slab and make – just take out the corner square of it?
TOM: You’re going to have that be separate slabs now. Depends on whether or not you want to see that. It’s always going to be a cut. So, no, probably not unless you want to make it an expansion joint and have it be completely separate pieces of concrete.
DEBBIE: OK. Very good.
TOM: Alright. Good luck with that project. Sorry that happened to you and thanks so much for calling us at 888-MONEY-PIT.
DEBBIE: Thank you.
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