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Roof deck snowmelt

RomanP
RomanP Member Posts: 102
Hello, gents

Started a new project in NYC. They call for snowmelt system on all three of their roof decks. The tricky part is.... it's a paver roof. Pavers are sitting on little styrofoam and plastic supports, so there's the gap between an actual roof and a bottom of the pavers. Theoretically, if I lay my tubing in between these supports, some convection and radiation should get the job done. The thing is, I never had an installation like that, so no idea if it would work properly. Any suggestions?

Thanks!

Comments

  • Zman
    Zman Member Posts: 6,993
    That is going to be a tricky one.
    You need to push roughly 100 BTU/sq ft to melt snow effectively. I don't know of an assembly where you can transfer that much energy through an air space.
    Usually a job like that would be planned from the roofing on up before the pavers are installed. You would have waterproofing, then drainage mat, insulation, a sand bed with radiant tubing then pavers.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Gordy
    Gordy Member Posts: 9,514
    So the snow melts, and seeps between pavers onto roof deck below? No, or very little pitch to roof?
  • Zman
    Zman Member Posts: 6,993
    edited April 2017
    Gordy said:

    So the snow melts, and seeps between pavers onto roof deck below? No, or very little pitch to roof?

    I have seen these systems before. The pavers are bigger and the sit on adjustable stanchions. The roof can slope up to 12" or so. The pavers remain level
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Gordy
  • JeffM
    JeffM Member Posts: 174
    You might want to take a look at Therma-HEXX panels. I haven't personally used them, but have seen them in person and the concept is reasonable. They are basically a hydronic panel made to the same footprint as the pavers and designed to sit on the same supports.
  • Zman
    Zman Member Posts: 6,993
    JeffM said:

    You might want to take a look at Therma-HEXX panels. I haven't personally used them, but have seen them in person and the concept is reasonable. They are basically a hydronic panel made to the same footprint as the pavers and designed to sit on the same supports.

    That is a clever solution. I do have to say, all those connections make me nervous. Maybe someone on here has had real world experience with that product.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • JeffM
    JeffM Member Posts: 174
    The number of connections has made me cautious in the past too. That risk is somewhat reduced because they are accessible for repair if needed - just lift up a couple of pavers and their panels and you can get at the connections. Having those connections exposed to all of the melt water isn't going to do them any favors though.
  • Leonard
    Leonard Member Posts: 903
    edited April 2017
    Structural load from all those pavers would be high.
    But it's possible to design any structure if you have the money.

    Here in NH design snow load is 45 pound/sq ft. Guessing pavers would take up most of l that.
  • RomanP
    RomanP Member Posts: 102
    Thanks for the input, gents. The roof itself will have a roof drain. I will have about 5" of space from the surface of the roof to the bottom of pavers. I think I will experiment with ultra-fin. Their system is suspended between the joists with aluminum transfer plates. I'll lay reflector on the roof. Suspend my pex tubing with ultra-fin plates 2" above the roof, probably, will double up on transfer plates and run high temp. Their rep is assuring me that it will work just fine and from the physics stand point of radiant I know it should. Wouldn't want to look like a donkey if that system doesn't perform and people paid an arm and a leg for it
  • RomanP
    RomanP Member Posts: 102
    I will definitely check out therma-hexx product. Thank you
  • Gordy
    Gordy Member Posts: 9,514
    RomanP said:

    Thanks for the input, gents. The roof itself will have a roof drain. I will have about 5" of space from the surface of the roof to the bottom of pavers. I think I will experiment with ultra-fin. Their system is suspended between the joists with aluminum transfer plates. I'll lay reflector on the roof. Suspend my pex tubing with ultra-fin plates 2" above the roof, probably, will double up on transfer plates and run high temp. Their rep is assuring me that it will work just fine and from the physics stand point of radiant I know it should. Wouldn't want to look like a donkey if that system doesn't perform and people paid an arm and a leg for it


    If they are willing to pay I'd have steam coming off the roof :p nothing like seeing your money well spent.
  • Zman
    Zman Member Posts: 6,993
    Do be sure to follow up on how this performs. I am genuinely curious.
    I suspect that carefully controlling your gaps, especially at the edges of the paver system will a key to your success.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RomanP
    RomanP Member Posts: 102
    That therma-hexx looks tailored for my project. It's expensive but let's see...
  • RobVerreault
    RobVerreault Member Posts: 3
    Hey Guys,

    A little insight into the Therma-HEXX product. The panel is specifically designed to work with pavers that are typically used with roof decks and terraces. These pavers are elevated off the pitched roof with a pedestal to achieve a level surface and allow for drainage. The panel is sandwiched between the top of pedestal and bottom of paver providing full contact with the paver to achieve efficient snowmelt. The panels are connected in rows with socket fusion welded connections between the panels, which is a very robust connection. The product is also used with sand set pavers on grade as it provides a very solid base and prevents settling of the pavers. Because of the heat transfer capabilities of the panel, they can be used under pool patios for solar collection. In this application heat is harvested from the pavers and used to heat the pool, this has a cooling effect on the paver surface. I hope this helps!
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837


    Be aware that ThermaHexx is not an oxygen barrier product, and that I am a little leary of the BTUH quoted based on the flow that one can reasonable expect to get through a 1/2" connection.

    ME
    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.
    Gordy