Electric radiant floor heat

Electric radiant floor heat. I need to encase this wire in a lightweight mix to distribute the heat evenly. They suggest a light weight gypcrete mix. I read a few facts and it looks very well suited for the hydroic radiant heat systems. I have used this wire system before in thinset & tile with no problems. This surface will be covered in a floating wood laminate. Only 150 sq ft, inch thick. I was thinking of using a cement sand mix instead of gypcrete. Should I use any additives with it? Oh yeah, it will be going over an uninstalled concrete slab. They suggest using reflectix (bubble foil wrap between the mix and slab. Anyone done this before?
Thanks TP
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One problem I see with the reflextix is movement. You put that down and it won't bond with the slab and may cause breakage of the mix. I don't know of any solution.
Another thing is the reflectix is not tested for insulating value unless there is an air space. While it's better than nothing, it's not much insulating value.

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TP wrote:

Bubble foil would be an odd choice. I'd think that it wouldn't have the compressive strength and the air could leak out over the years.
Look into Wedi board - it's a 1/4" or 1/2" foam panel with fiberglass mesh on both sides covered in an acrylic/cement coating. Think Durock with a foam core. It's also recommended by some of the radiant manufacturers.
Gypcrete or other self-leveling topping is the easiest thing to do in most cases. The sand mix would be a distant second in my mind. It would work but it's a lot more work than mixing and pouring. If you do use the sand mix, latex additive would probably be wise. How thick is the mortar topping going to be?
R
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Polyisocyanurate board, eg 1" Atlas Energy-Shield roof insulation.
Nick
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snipped-for-privacy@ece.villanova.edu wrote:

Thanks for the replies. I was going with my gut and using a polyiso board base, then the 1/2" gypcrete on top. Im glad I asked about the bubble stuff cant figure out why they recommend it. I see gypcrete isnt sold to DIYers, so that is why I may go with the sand mix.
TP
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wrote:

Somewhere I may have a recipe for gypcrete. Email me and I'll send it to you, if I can find it.

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