Should I install aluminized radiant barriers under my SunTouch floor? Will that direct the radiant energy upwards?
We do not think so. To reflect radiant energy upward, you need an air gap. If you install that barrier below the floor (like in the joist bay) and allow for an air gap between it and the subfloor above, then the radiant barrier will help insulate your warm floor. When you install thinset over the SunTouch mat, that masonry bonds to the layer below through the gaps in the orange weave. If you put in a barrier below the mat, you can compromise that bond and actually make your finished floor more subject to cracking.
