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Overfloor radiant heating

drawerskis | Posted in Energy Efficiency and Durability on

Hi folks,
Doing a remodel. Changing out my floors and I’ve always loved the idea of radiant heating and trying to make it work. I have a concrete perimeter with a wooden subfloor over a crawlspace. So, not the ideal set up (as a concrete slab seems best from my limited research), but it seems still possible.

I’ve decided to go with the setup these guys offer:
I might not buy their package but use their idea. Basically, PEX tubing in aluminum plates, over wooden subfloor, separated by OSB. I realize this might not be the most effective radiant setup, but alas, every other option I’ve searched seems price prohibitive to me. Seems like all I’m paying for is PEX (cheap), aluminum plates (sorta cheap), and OSB (cheap). Money-wise, I can do this.

A few questions for the experts here:
1) what do you think? Is this an ok idea?
2) Do I need a insulating barrier under the PEX and over my subfloor? Could you please give me specifics as to what is best I am dumb at this?
3) I know I need to get engineered wood floors (real wood, sadly, will cup). But can I put a really thin (1/4″) plywood over the OSB and PEX? I need to do a lot of work in my house after the radiant is installed (drywall, insulation) and I would love to have a thin plywood to prevent the PEX from being punctured.

Thank you and happy holidays to all.

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  1. user-2890856 | | #1

    Your idea is fine if that is what you have determined . Depends on what your time is worth but there is nothing wrong with sweat equity .

    All radiant heat requires insulation (resistance= RValue) on the opposite side of the space to be heated . Heat travels omni directionally (360*) form it's source . The insulation below your subfloor should be sufficient at R13 or greater .

    Who told you you must use engineered as opposed to REAL wood ? This is nonsense and a wives tale started by people who did not take the right precautions . Only poorly installed hardwood floors , those with no proper moisture control and those designed with no regard to surface temp will suffer . See , 100% of hardwood problems do not have radiant to blame , often times it is an easy Patsy or Fall guy .

    I would suggest you stay off internet forums and reading old wives tales and visit somewhere like and ask for some truly good advice from REAL Radiant Professionals that have been getting people out of jams and helping them avoid getting into jams for 15+ years . A post in the radiant professionals section or Main Wall would be prudent . You could also visit healthy heating .com . Start with radiant myths . The science is all there and stay away from the internet peddlers who will be gone after they have your money .

  2. GBA Editor
    Martin Holladay | | #2

    Designing a hydronic distribution system (for example, a radiant floor) takes experience. The first step is that same as for any heating system: you need to perform a heat loss calculation to determine your design heating load. Once you know your design heating load, you can begin designing your system: variables that you have to consider include water temperature, flow rate, circulator sizing, and tubing spacing.

    If you get the design right, everything will work well. If you don't have much experience with these issues, you'll discover that there are many ways to mess things up. You may want to hire a contractor who has experience with hydronic systems to help you.

    Here are links to articles that discuss installing hardwood flooring over radiant floors:

    Maple flooring over radiant heat

    Installing Hardwood Floors over Radiant Slabs

    Hardwood Flooring over Radiant Heat

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