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    Garage Slab Thermal Break (21 Posts)

  • steveg steveg @ 11:57 AM
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    Garage Slab Thermal Break

    Anyone have any new methods for creating a thermal break between a radiantly heated garage concrete slab and an outside apron or for a partially snowmelted slab? 
  • zacmobile zacmobile @ 4:39 PM
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    Separate the two slabs with min 2" styro and fasten an aluminium tread over it.
  • hot rod hot rod @ 6:09 PM
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    a plastic cap strip

    is available to protect the edge. The product I used has a H shape, with a removal pull tab across the top. Once the concrete sets you pull the top strip and it provides a channel to apply a bead of polyurethane caulk.

    Mine has been in place for 10 years now, I did replace the polyurethane once after some gasoline softened it. It fits on 1/2 wide foam or homosite, I suppose you could triple it up, but it leaves a wide gap to caulk.

    I like the idea of a aluminum or stainless steel metal cap that could be formed locally. something that holds up to road salt and cleaning. The polyurethane handles any movement between the warm building slab and the cold driveway slab, and prevents water from getting between the two slabs.
  • SWEI SWEI @ 6:16 PM
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    got a link to that strip?

    I could really use something like that for slabs under walk-in freezers.

  • hot rod hot rod @ 10:02 PM
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    a different brand

    from what I used, but they have some interesting seals that should work for your project.
  • SWEI SWEI @ 10:46 PM
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  • Steve Whitbeck Steve Whitbeck @ 5:14 PM
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    Why all of the extra cost -  I just use the brown board the cement guys use. It's not like you are heating your garage to 70* all day long. Yeah it melts the snow out 12" but it can't cost that much in wasted heat. I am heating my barn to 50* all winter with only 90* water from the boiler.
  • heatpro02920 heatpro02920 @ 7:38 PM
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    Hey steve, I don't know if you are kidding or not lol, I personally don't want to heat outside at all, not even an inch, other wise why insulate the attic, I know its nice not to have to worry about snow on the roof, but I would rather take it off with a snow rake if it ever an issue....
    Thermal breaks are good, esecially when it comes to the system shutting down, with no break you dont have long to find out its off and fix the problem, where with a break I have seen systems down for days with out freezing....   I have seen pleanty old systems with no breaks freeze, and I dont know if you ever tried to defrost a frozen pipe with frozen cement around it, but it ussually takes waiting until the sun does it for you--- or a lot of jack hammering....
  • Steve Whitbeck Steve Whitbeck @ 10:12 PM
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    I always keep the tubing away from the door openings by at least 18 inches. never had one freeze. even with a big heat break the earth is still going to transmit heat.
    even with 2 inches of blueboard around the perimeter of the walkout basement walls you will still not have snow up against the cement walls. And I run insultarp up onto the footings to break the slab contact to the vertical walls. I am just saying that the sayings won't pay for the effort and cost of a break that would make it worth it.
  • Zman Zman @ 11:15 PM
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    I was under the impression that insultarp has little real insulation value. It's just 2 layers of double bubble and a thin layer of compressible foam. It has been debunked and banned in my area. 2" ridgid is the only thing allowed.Perimeter insulation is required.
    I like the ideas for capping the break.
  • SWEI SWEI @ 11:30 PM
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    Insul-tarp is worth a read.
  • hot rod hot rod @ 12:51 PM
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    Robert Bean

    Has some good info about under slab and edge insulation. He had an article in www.hpac Maybe March last year, worth a read.
  • SWEI SWEI @ 4:06 PM
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    Robert Bean

    March issue had the second part of something called "Together Forever" -- was that it?

  • Steve Whitbeck Steve Whitbeck @ 9:49 AM
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    Lets see you cover the footings with 2 inch blue board.
  • heatpro02920 heatpro02920 @ 12:05 PM
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    I had to go check

    what the name on the stuff I use is, lol  Mine is prodex total, works really well, some times when the budget is tight I use a different one, its just 2 layers of bouble wrap type insulation....
    I stay 8"s off outside walls with my tubing when doing a floor, My office building is at 70 and we just got 12" of snow day before yesterday and it doesnt look at all melted {except where the gutter drains are since we are in melting temps rite now}....  Im sure the losses are small but why pay to melt snow, I go out of my way to make sure the systems are as efficient as possible it seems silly to not make sure my heat is not going to waste, even if its running through a 89% appliance...   When I as building my office I wanted to put an unheated entry way where everyone could take off their jackets and then enter the climate controlled space, but then my office manager was the first one to say "wait a minute, then I have to put a cold jacket on in a cold room" and I figured out that it was a bad idea....   But I am cheap when LP and oil are $4 a gollon...   I like to pull up to my house and see a snow covered roof and ice stuck to the corners of the stucco....  It means all that money I spent on insualtion is working for me...   Although the money would probably have been better spent geting my sons classes on how to shut off the bathroom fan {I can not count how many times I come home and that hting is humming away blowing my BTU's outside}....
  • SWEI SWEI @ 12:15 PM
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    bathroom fan

    vacancy sensor might work there.

    Have you seen the new Broan Ultra?
  • heatpro02920 heatpro02920 @ 9:26 PM
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    thanks swei

    Im going to look into it, I was thinking about stripping a hot lead and running a metal switch so they get zorked when they try to leave the bathroom with out shutting the fan, but your way sounds more humane and less likely to cause a fire...
  • Zman Zman @ 5:32 PM
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    I am a little blown away that you guys are still using insultarp.

    Why not just use visqueen? I think the real insulating values are similar and it costs less.
     Yes it is difficult to apply blue board to footings. I can be done. I also don't like the toxins in blue board. Closed cell spray foam works very well.

    I intend no disrespect, but there is no science to support double bubble.
  • SWEI SWEI @ 5:58 PM
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    in XPS are about as minimal as you can get for a polymer.  I'd worry more about polyurethane or polyiso.
  • Jim Godbout Jim Godbout @ 6:56 PM
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    Code on insulation required for heated slab

    We have very strict code compliance here in Maine building code requires R15 foam
    We use 3 inch .Crete Heat and 2" for thermal breaks for radiant floor installs
    This is actually National code
    Jim Godbout
  • Kevin Koenig Kevin Koenig @ 12:43 PM
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    Thermal Break Details

    Here are some construction details we have found to be very beneficial ln reducing edge losses.  Its the small details that seperate a good installation from an OK installations. 
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