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Radiant Heat Questions

Ringo311 Member Posts: 22
Part of my home that was a house addition (14'x24') was built on an uninsulated concrete pad. I live in Western NY so the floor gets very cold in the winter (as does the room).

Im adding on to the room 10' out (making it 24'x24') and building a new roof. The only heat source for the room is a gas fireplace and I want to add radiant heat to the entire completed room. 

What are my options for installing over the uninsulated pad and for matching the existing pad? <strong>Should I match the existing floor with a poured concrete pad or with wood framing floor and joists</strong>? I do have the option of raising the finished floor elevation several inches if necessary so I could get some foam boards over the old pad. Im not keen on breaking up the old pad and insulating underneath but its possible I would do it.

Any advice would be appreciated.


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    You're going to have to..........

    Insulate the pad.  Otherwise it just wont perform well.  I would match the concrete pads in elevation, insulate above the pad, and frame over that.  A better choice, if this makes the floor too high, may be to do a radiant ceiling, but still insulate over the pad.

    There was an error rendering this rich post.

  • Gordy
    Gordy Member Posts: 9,546
    Floor covering choice

    What will it be?

    Radiant ceilings are a wonderful alternative. Will the ceiling be cathedral?

    Floor transitions from adjoining room?
  • SWEI
    SWEI Member Posts: 7,356
    over the top of existing slab

    Roth Panel or Raupanel are both pricey, but they deliver upward heat with little waste downward.  Depending on which you choose, you'll gain 3/4" to 1-1/4" there.
  • Ringo311
    Ringo311 Member Posts: 22

    The floor will be hardwood (3/4"). There is a plywood subfloor fastened to the existing concrete floor. So what if I matched the existing and proposed concrete level and matched the plywood subfloor then put down 2" of rigid foam? I could lay 2x4's above that, lay out my pex and fill with gypcrete to the top of the 2x4's. then fasten the hardwood to the 2x4's. it's bamboo so they are all equal length (no short pieces). This would leave about a 3" difference in finished floors, there's only a 36" opening to enter the room from the main part of the house.

    I can't see any other way to get the insulation I need. Should I build it up with insulation to make a proper step?
  • SWEI
    SWEI Member Posts: 7,356
    so height is not an issue

    in the existing slab area?  That's unusual to say the least.  Adding height usually implies re-framing doors, raising electrical outlets and perhaps switches, and moving a few windows.
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