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Tar Paper + Concrete + Radiant Heating

pyrogerbil87 Member Posts: 1
edited October 2020 in Radiant Heating
I am planning to install radiant heating in the 2nd floor of my home and was concerned about the smell from tar paper. My floor will consist of wood planks, tar paper, pex piping, self-leveling concrete, and wood flooring. My concern is whether the tar paper smell in either the upper floor or lower floor when the radiant heating is on.


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Not a problem, although I’m concerned about the sandwich of gypcrete then hardwood over it.

    There was an error rendering this rich post.

  • GroundUp
    GroundUp Member Posts: 1,955
    I wouldn't think it'd smell, but I am wondering why you'd put tar paper over your planks at all. To keep the gyp from dripping through? How thick will the gyp be?
  • Paul Pollets
    Paul Pollets Member Posts: 3,658
    Red rosin paper should be used, not tar paper. The only hardwoods that should be used for direct placement on the slab would be pre-engineered hardwoods, rated for the application. Strip oak flooring can be applied if 2 sheets of plywood are placed on the floor prior to installing the strip oak. (Bollinger method) That method is rarely used anymore due to the cost of the plywood and the additional height of the finished floor.
  • TAG
    TAG Member Posts: 755
    Why the concrete ? are the floors way off?

    I have done about 10 projects (personal) -- pushing 30 years -- all of them have radiant under wood floors. Including some with very wide planks -- 10+ inches.

    They all had heat loads done and did not have 150 degree water running through them.
  • Zman
    Zman Member Posts: 7,605
    It sounds like this might be an older home. Has anyone evaluated this structurally? I would be concerned with both the additional dead load and the deflection.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 22,467
    edited October 2020
    probably what you have is asphalt impregnated felt paper :)
    It can handle the temperatures that you would typically run in gyp pours. Most of the engineered hardwood can be floated over gyp, tile sheet products like linoleum.
    You need to run the system for days to dry it out, lots of water in gyp pours and it comes out the top.

    A sealer can be put on also. I have seen tile over gyp, but you really don't want to get it wet. Even sealed it tends to come apart when wet, not unlike sheetrock.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • fuzzyjohn
    fuzzyjohn Member Posts: 1
    Did you ever figure this out? I’m looking for the same answer. 
  • mattmia2
    mattmia2 Member Posts: 9,941
    I think everyone suggested wood and aluminum transfer plates of some sort would be the way to go.