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radiant over slab

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hot_rod
hot_rod Member Posts: 22,158
they offer some high psi gyp products they claim can be colored and used as a wear surface. The gyp products seem to be a lot less prone to hair line cracks.

With a good installer you get a very smooth and flat surface.

Thin concrete, under 3-1/2" can be a problem as a finished surface.

I have heard of "super mixes" that use small aggerate and a bunch of special admixes for thin crack free installs. Check on the various concrete webpage.

David Pettigrew of Diamond D company in Capitola CA metioned a thin double pour method in the 2006 issue of the RPA Flooring Guide. I spoke with him on the phone once, he has some good tips and formulas for thin radiant pours.

hot rod
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream

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  • Mark_7
    Mark_7 Member Posts: 123
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    radiant over slab

    Have a job I looked at that the customer wants radiant heat over top of existing slab. Talking to carpenter, the customer wants stained concrete poured over radiant. Any thoughts on the install. Options,3/8 barrier insulation,heavy wire,run tubing,2" concrete. Or barrier insul. veiga snap panel,tubing, 2" concrete. Any other options?
  • bigwilly104
    bigwilly104 Member Posts: 50
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    Cracking

    Make sure you put in a disclaimer about cracking in your contract. a thin slab like that can cause problems. Every tube makes the slab that much thiner in a nice straight line to. I wont put inslulation in between just edge insulation. if the contractor uses a bonding agent the old slab and new slab with bond together also.
  • Paul_11
    Paul_11 Member Posts: 210
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    use barrier insulation

    You didn't mention much about the original slab. How thick, what kind of insulation is under it.

    But I like using a 3/8" bubble type insulation to isolate the new slab from the old slab. This greatly increases how fast your new radiant floor heats up and cools down. You have more control that way. If for some reason you don't care about that and do want to use the increased mass of the old slab with the newm, they don't isolate it.


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