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Retrofit on slab on grade.

HAROLDS Member Posts: 9
I am looking to install radiant heat in my family room. The room is 24' x 24'. the issue is the room is and existing slab on grade. We are going to install tile and want the radiant to warm the floor to increase the comfort of the room.

I have been looking at the quick tr-ax system but the cost is really up there. I need to limit the thickness of the tubing to 1/2" in order to allow the cement board and tile to not become to great of a "step " as you enter the room.

Does anyone have any thoughts and suggestions


  • Al Letellier_21
    Al Letellier_21 Member Posts: 402
    slab on grade

    You are limited in your options to heat that floor without adding a lot of thickness. You can groove the concrete but what is under it for insulation? You may end up spending lot of money to heat the slab and the ground below. We have done several rooms like this with good results but it involves dropping down a layer of 1" marine plywood and QuikTrac above it.........you could consider doing electric radiant if floor warming is all you are looking for. Several manufacturers have mating that can be laid down under tile for floor conditioning.

    Good luck
    HAROLDS Member Posts: 9

    I have done another room in the house with electric mats and it is much to expensive to operate. I have thought about placing a sheet of aluminum down on rosin paper and placing sleepers on 12" centers. Then cement board and tile.

    I know the slab has 2" of insulation around the perimeter. No idea what is under it.

    How much heat will go down? heat rises? I thought the rosin paper would act as a thermal break?
  • furthur
    furthur Member Posts: 25
    you can drill it...

    If you get a concrete bit, you can drill a hole int he slab to check what's under it.  I did mine to see, and found...nothing.  In Alaska.  Really?.  Anyway...  easy to patch with a bit of wet concrete, or even epoxy.
    Just a doit yourselfer, learning the hard way, as usual.
  • Gordy
    Gordy Member Posts: 9,514
    edited January 2011
    If you are going to do that

     Then I would do heavy gauge aluminum plates, and tighten up to 8" centers with ceramic tile.

     Conduction is your friend. Putting an aluminum sheet then plywood over it is not getting the heat to the finished floor, as a matter of fact it would probably transfer it to the slab more than your finish floor.

     The conduction chain for the emmiter is the water to the tubing wall to the plate to the finished floor. Any break in the chain creates higher water temps, and or less output. The omega aluminum plate design wraps the tubing to help achieve this. Just laying tubing on a sheet of aluminum does not give much benefit.

    Radiant heat does not rise.. Hot air rises.

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