A popular feature of Heat-Sheet is that it can eliminate the need for a layer of poly/vapor barrier.
However, some builders are hesitant to skip this step. How should a Heat-Sheet installation be detailed to properly eliminate the poly?
First, if you need to protect against radon, you will still need the layer of poly/vapor barrier.
Otherwise, to eliminate the layer of poly under Heat-sheet:
- Your layer of Heat-Sheet needs to be R10 or thicker and needs to meet or exceed a compressive strength of 25 psi (is Type 3 and Type IX EPS), and
- You will need to seal the perimeter of Heat-Sheet layer to footing or the wall and apply vapor barrier tape over any cracks or broken lap joints.
