Finding The Right Natural Flagstone for Hydronic Heat

by Pete Sutsos
(Sonoma, CA USA)


I was wondering if you could answer a technical question for me about flagstone? We are building a home that is going to be using hydronic heat (in floor radiant) and are planning on using flagstone as an overlay flooring material over the concrete floor that is going to be poured to support the hydronic heat tubing.

We want to use an irregular style neutral color (brown or sandy color) natural flagstone. Can you make some recommendations of what would be the best to use for our application? We want the floor surface to be as smooth as possible and are going to have a seal coat placed over the top.

Thanking you in advance for your assistance and direction.

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most stone should work
by: David

Dear Pete,

My dad has laid stone many times over heat mats, but I can't remember him laying any stone over any type of hydronic heat.

I would think that just about any stone that you find or like would radiate the heat. I actually have it in my house with flagstone. (I bought the house with it. My dad didn't do it.) We love it! The heat is so even.

The flagstone in our house is a hard, buff flagstone. I know you're looking for a smooth stone, but I think it should work on that.

Before you lay it though, do a test run. Get some samples of the stone that you like and set it over something warm and see how it does.

Also, talk to the stoneyard where you buy it. A lot of times they know a lot about the stone that they sell.

I'm sorry I couldn't be more specific, but we've never done it and I don't want to say anything that we don't know.

Great luck with your project!

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