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  1. #1
    Join Date
    Oct 2007
    Posts
    5

    Hydronic over existing slab

    Installing hydronic heat as part of a remodel of a ranch house in the northeast. Approx. 1000 feet over existing slab and 150 ft over basement joists. Slab is not level but levelling has been achieved with tapered sleepers where necessary. Considering using Warmboard as subfloor, as it seems to be a good (if not inexpensive) solution for our project.

    Questions:
    Where warmboard is going over joists, should i use foil insulation below the subfloor?

    Where warmboard is being attached to sleepers, will foil insulation on the slab work to improve efficiency?

    Where concrete is at high points, and no sleepers are present, will I run into any comfort issues if I don't put down insulation below the warmboard, or is it simply a lack of efficiency?

    We are considering the use of an outdoor reset control but may wait to do this later after we see performance, because of cost concerns. Thoughts?

  2. #2
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    You must insulate the whole floor. Lay down 2" foam, staple pipe to foam and then do a gypcrete pour over. You can level the floor with gypcrete if it's not too out of level.
    Karst means cave. So, I search for caves.

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