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Uponor Joist Trak & Uneven Subfloor Panels

HFC Member Posts: 29
While installing Uponor Joist Trak on the underside of our bathroom subfloor I noticed where the adjoining subfloor panels meet, (the tongue & groove) one panel is displaced higher than another.

I would imagine having a portion of the Joist Trak not in contact with the subfloor would create cold spots. Is there a preferred method to address this? Does some type of filler need to applied to the underside of the subfloor and then sanded to create a flat surface for the Joist Trak?

Thanks for taking the time to read my post and consider my question.

<img src="http://www.fototime.com/AB27197DE628CE8/large.jpg" width="1024" height="683" alt="" />


  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    I don't think it is going to make that big of a difference...

    But if you are really concerned with it, maybe you could take some heavy duty aluminum foil, and place it between the gap and the plate to enhance conductivity at the point of no contact, and then screw the living bejezits out of that area, like 3" O.C. ...

    I seriously doubt that many contractors even stop to give it any thought.

    How is it that the gap showed up? Did the sub floor warp.Maybe you could take 2 X 2's. and screw them to the side of the joist, then run screws through the 2 x 2 and into the subfloor, sucking it down?

    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.
  • Jack
    Jack Member Posts: 1,046
    I'd be more concerned

    With the hi/low on the plywood. What type flooring goes above it? If it is tile that seam could give a real problem in the futrure. At least it could be a squeaker. Get the floor set correctly and your problem goes away.
  • MikeG
    MikeG Member Posts: 169
    Unlevel floor

    As a previous poster said the topside may be more of an issue.  I've seen this often in new construction where the subfloor gets wet.  The edges especially the T&G sides swell up. OSB seems to be worse even though they say they put a waterproof coating on the edges.  Generally the subfloor is glued with construction adheasive.  I've also had issues where the adheasive started to set up and the plywood or OSB was not drawn up tight.  Had to use a belt sander on high joints to lay a wood floor or used floor leveler to taper out the seams.  Usually if carpet is installed they put down underlayment but even with pad and carpet who wants an uneven floor. Tile floors directly on plywood can be leveled out with thinset, but issues arise if you have too much variation in thickness especially with potential stresses in radiant floor.  The underside may not be that big of an issue depending on how much of an area you have to bridge with the plates.  They don't bend that much.   Just some things to consider.  Mike
  • HFC
    HFC Member Posts: 29
    Thanks everyone

    I believe the displacement of the subfloor panels is due to a major earthquake we experienced back in 1989 and it runs across the three bays where the Joist Trak panels are installed. Currently there is underlayment on top of the 3/4” plywood subfloor with vinyl flooring on top. Later this year we will remodel the bathroom above and remove the underlayment and vinyl flooring and replace it with tile. Since the ceiling below the bathroom is currently open I decided to install the plates and pex now.

    The displacement between subfloor panels is 1/8” or less so I think I will use a belt sander to bring them flush. I did one as an experiment today and I think this will work.

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