Flagstone over a Existing Concrete patio

by Dan
(Ambler, PA)

We have a concrete patio which has some cracks on it that we would like to repair. We are also thinking of extending the patio. We do not want to rip up the existing concrete patio. We would like to put Flagstone over the existing patio. We live in PA. Does the Flagstone have to be cemented in, on top of the existing patio? Or can we just lay some sand over the concreted patio and then just lay the flagstone on top of that? Maybe we can use concrete just for holding down the flagstones on the edges? What do you recommend? Thank you for your time. By the way, you have a great website with lots of great information.

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by: Anonymous

lay with fine layer samd an put gator dust in cracks its repair able an easy..

lay it in cement
by: David

Hi Dan,

You actually lay the stone in cement as you're going along. There's about 1/2 to 1 inch of cement that you put under the stone.

You could get cracks where you have them in your concrete over time. It's hard to totally stop settlement of concrete. However, we've found that the cracks happen in the joints, so you can easily replace them, if need be, in the future.

Take care,


Thank you
by: Dan

Thank you for the speedy reply. So, would you just put more cement over the concrete patio and lay the flagstone on that? I was afraid that flagstone was going to crack somehow and it would be hard to repair it. However it looks much nicer in cement in your pics.

best to use concrete
by: David

Dear Dan,

Thanks for the compliment! It makes my dad happy that his knowledge can help out so many people.

You really can't lay the stone in sand on top of concrete. We've heard it being done, but it's just as much work as if you lay it in concrete.

Laying your stone in concrete will be much smoother and nicer over the years. Check out the difference here:


If you want to extend your patio, you'll need to pour some more concrete, so make sure your contractor ties it in with your existing patio.

You can check out our free tutorial on the process for laying stone in concrete here:



or it might be worth it for you to spend $15 and check out our DVD.


Great luck with your project!!


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