Use of Reflectic for infloor radiant heat

I have a 170 sq.ft.log cabin i want to put infloor radiant heat in..It has a true 1"x12" wood plank floor with one layer of Reflextic (Reflectic=aluminum foil on both sides and 2 layers of air bubbles inbetween)under it....It was suggested to me to put 2 layers of Reflectic on the wooden floor then the Pex tubing,then 2 inches of what is called 3/8 mix concrete....My question is will the Reflectc provide enough reflection for the heat ?????????? I have used this Reflectic product before in ceilings and walls and it is great.......Thank u

I have a couple of questions, which are probably best answered by the manufacturer:

1) This doesn't look like a product that you can walk on. It looks like something which should be UNDER the wood floor, between the joists.
2) It doesn't seem like the kind of product you would use 2 layers of. Why not one layer of the reflectix, and conventional fiberglass batts under that to increase the total R???

I think it would make a truely lousy underlayment for the concrete. While concrete is quite good in compressive strength, it isn't all that great in tensile strength - I think you'd end up with it cracking since what you are talking about is basically metalized bubblewrap. Adding thermal mass to the floor is good. I'd put insulation under the floor. Note, for a radiant barrier insulation to work well, it CAN'T touch the surface...it needs an air gap, otherwise it becomes a conductor. 1/2" is fine.

jadnashua said:

I think it would make a truely lousy underlayment for the concrete. While concrete is quite good in compressive strength, it isn't all that great in tensile strength - I think you'd end up with it cracking since what you are talking about is basically metalized bubblewrap. Adding thermal mass to the floor is good. I'd put insulation under the floor. Note, for a radiant barrier insulation to work well, it CAN'T touch the surface...it needs an air gap, otherwise it becomes a conductor. 1/2" is fine.

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I wish i could put insulation under the planks BUT the guy built it with 2"x8"s for floor joists that rest on the solid (bedrock) ground...I would have to tear the whole floor up and i am not up to that...Also when i lay the PEX tubing out i will only be able to go with 2 inch thick concrete...Where i am at in a rural area they do not have that Gypcrete product,they recommend a 3/8 mix concrete with fiberglass mesh...I wish i could insulate it better....Any other ideas ??? Thanks

jimbo said:

I have a couple of questions, which are probably best answered by the manufacturer:

1) This doesn't look like a product that you can walk on. It looks like something which should be UNDER the wood floor, between the joists.
2) It doesn't seem like the kind of product you would use 2 layers of. Why not one layer of the reflectix, and conventional fiberglass batts under that to increase the total R???

Click to expand...

See post #4..Any other ideas ??? Just stuck where i am and do with what i can i guess..

Wediboard is not cheap, but in the thicker sheets would provide you with some insulation. It is a specially coated foam board that you set on the floor with thinset. It is designed to put tile on, either for floors, walls, or in a shower. Note, you'd have to put some plywood down first (minimum of 1/2"), as planks move too much, and would break the bond. You might want to call them up and see what they have to say, they may not think it's a great idea. Wood itself, is a poor insulator, but it does provide some.

Thank u all...