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Any anecdotes about transfer plates under uneven T&G?

Gordan Member Posts: 891
I'm talking significant cupping on tongue-and-groove pine running perpendicular to the joists (of course.) Should I just use more screws to force the extruded plate to conform to the subfloor? Any other way to increase contact? Any reports on how well it worked for you, if you've ever done it?

I'm using pex-al-pex, so expansion noise or tubing popping out of the plate if things are not perfectly aligned should not be an issue.


  • Tim P._3
    Tim P._3 Member Posts: 50
    increasing contact

    I have added screws here-and-there where necessary without any noticable issues.

    If you have an entire floor that is going to require additional screws I would worry about squeaking.

    Never tried it (or heard of it being used), but I wonder if a thermal compound could be used for increased conductivity?

    Google "Virginia Thermal Mastic".  $200 for 5 gals doesn't seem too cost prohibitive.  Wonder if it would actually do anything?
  • Gordan
    Gordan Member Posts: 891
    Yeah, well...

    Not so worried about squeaking because there's a 4" slab poured over this subfloor. This is all original construction, in my own 1951 vintage home. What I *do* worry about is what air gaps may have developed between the concrete and the subfloor, where I can't even get at them.

    I guess I'll hope for the best. It's a fairly small area, just the entrance hall, so it's not a huge investment in time or materials. Thanks for the pointer, I don't think that a thermal compound would be a good match here but it could definitely come in handy elsewhere.
  • Gordan
    Gordan Member Posts: 891
    edited February 2012

  • Paul Pollets
    Paul Pollets Member Posts: 3,509
    Heat Loss

    I'd be concerned that the R value of the T&G + 4" of concrete will properly heat the space. Response time will be very long, at least.
  • bld999
    bld999 Member Posts: 47
    No fun solution

    I am pretty sure that if you wanted to, you could remove several of the cardecking planks and expose the underside of the slab without compromising the span capabilities of the 4" slab. Say remove every third or fourth plank? A decent 4" slab could easily and safely span across the 5.5" width of the missing plank [ i'm guessing 2 x 6 T&G]. You could probably wear out a sawzall doing it, and it wouldn't be much fun, but you could then silicone your plates directly to the bottom of the slab, or whatever attachment method makes sense, Is this the 4 x 6 beam plus 2 x 6 cardeck system?

    I wouldn't suggest this if it wasn't a small area....
  • Gordan
    Gordan Member Posts: 891
    It's 1x6 decking

    laid perpendicular on top of 2x8 joists. The joists are on 16" centers. Frankly, I doubt that the decking is serving any structural purpose presently, but I guess something had to hold up the concrete while it cured. Cutting out every other would accomplish little - I can't imagine laying tubing perpendicular to joist bays, which is how the decking is oriented.
  • kcopp
    kcopp Member Posts: 3,990
    Ouch really....

    4" of concrete and the wood.  Yikes! I think you would be better off going on top w/ either over pour, climate panel or cutting grooves in the top of the concrete.
  • bld999
    bld999 Member Posts: 47
    1 x 6

    Well, removing the wood is a bit easier then, but the number of obstructions might defeat it [pipes, wires etc]. Setting a skilsaw blade to 5/8 and running the 1.5" shoe against the joist would leave you an open concrete width of ~ 12". 

    I guess it depends on how important that contact with the concrete is.   Beware, crazy remodel contractor talking here...
  • Gordan
    Gordan Member Posts: 891
    I'm not sure I understand

    UColorado's R value table says that poured concrete is R .08 per inch. So four inches would still be less than half the R value of a 3/4" hardwood floor. I'm using extruded plates at 8" o.c. and there's plenty of room for excellent insulation below. What am I missing?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839

    Watts Flex plate. Flexible carbon fiber transfer plate


    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Gordan
    Gordan Member Posts: 891
    Mark, I looked at those...

    You'd think that with all the "extensive testing" that they've done that shows their plates outperform extruded aluminum plates (which ones?), that one would be able to find some sort of output graph. If such a graph exists, it must be well hidden because it's not in any of their manuals, specifications or brochures that I have seen. Instead we get a thermograph that's ambiguous at best, and we're supposed to make quantitative commitments on behalf of Watts that Watts is unwilling to make on its own behalf. It rubs me the wrong way.
This discussion has been closed.