How to Install a Patio

LESLIE: If the warmer weather is making you want to get outside, you’re like Vince in Florida who wants to do a patio.

Vince, how can we help?

VINCE: I’m a do-it-yourselfer. I live on a pond in Land O’ Lakes and I want to do an open patio, a flagstone patio, and I know I have to pull the side up and cut down and lay a sand foundation. I’ve never done one before. I don’t know how much sand to lay and then whether to put grout in between the flagstone or can I fill it with sand so when we get those wonderful summer showers that it doesn’t start to buckle my patio. How much sand do I need to put in as a foundation?

TOM: Well that’s a great question. Let’s take it step by step. First of all, you need to strip out all of the sod, like you said.

LESLIE: Do you then want to put weed blocker?

TOM: Well you could. But if you put a proper gravel base in – I use a gravel mix for this. Basically it’s a finely-ground gravel mix and it’s very, very compactable. So you don’t put the sand in as the base; you put the gravel mix in as the base.

VINCE: Oh.

TOM: Once you put the gravel mix in and you tamp it down – and I would recommend renting a mechanical tamper for this because it’ll do a really good job of compacting it – and this is where most people go wrong; they don’t compact the base enough. When you’re done, you ought to have a perfectly flat, hard, gravel base that’s just like – when you walk on it, it’ll be just like walking on a concrete patio. It’s that hard.

Now when that’s done, then, on top of that, you can start setting your flagstone or your paver brick.

LESLIE: So no sand at all.

TOM: Well, really, no sand at all; just a little bit maybe, especially when you’re talking about flagstone if the bottom is uneven. If it was paver brick and perfectly flat, you wouldn’t need any sand at this point.

So what you want to do is go ahead, set the flagstone, use a little sand if you have to, get the mortar joints as close together as possible, and then you can use a mortar on that. I would recommend an epoxy-based mortar that’s a little flexible because otherwise it’s going to fall out pretty readily.

Have you looked at the paver bricks? Because they’re probably a more durable option than flagstone.

LESLIE: And you don’t need grout, right?

TOM: And you don’t need grout either.

VINCE: Oh, is that right? Let me just ask, how much of the gravel mix do I put in? A couple inches or …?

TOM: How thick? Yeah, you’re probably going to want it to be at least, I’d say, 3 to 5 inches.

VINCE: OK, so I’m going to put that gravel base and then I can just put a little bit of sand and then the flagstone on top of that.

TOM: Correct.

VINCE: OK.

TOM: Alright, make sure you retain the edge, too.

VINCE: So just maybe like a 1x …

TOM: Well there are metal retaining strips that work for patios that you could buy or you could do a wood retaining edge.

VINCE: Oh, I’ll send you a picture when it’s all done and I’m sitting out there having a lemonade.