Thermaboard vs Warmboard?

juliasanfrancisco

My architect specified Warmboard and my contractor tells me he wants to use Thermaboard. We are not doing structural subfloor - the plywood is already down. Is it a good substitute or are there more manifolds and smaller panels?

Alan (California Radiant) Forbes

Warmboard-S acts as subfloor AND radiant substrate. It's 1-1/8" thick and is usually used in new construction.
Warmboard-R is 13/16" thick and is used where there is already a subfloor.
Both products have a high quality, thick aluminum layer that is very effective at pulling the heat out of the tubing.
Thermalboard is a good product and I have used it on many projects. You will have more loops with Thermalboard because it uses 3/8" tubing where Warmboard uses 1/2" tubing.
Warmboard-R is 3/16" thicker than Thermalboard and I consider it a better product because of the thickness of the aluminum. If you look at their engineering notes, you get better heat transfer at lower water temperatures than other products.

Warmboard

As Alan mentioned, our Warmboard-R product would be the product to use for this situation. The panel is 4'x2' and is 13/16" thick. Thermalboard is 16"x48" and 5/8 thick. Hypothetically, on a 2000 square foot project, Warmboard-R will require about 3000 fasteners, while Thermalboard will require about 8500. You would also require about 2100 linear feet of tubing (with Warmboard) vs 3000 with Thermalboard. The narrower tubing used with Thermalboard limits loop lengths to 200-250 linear feet. Warmboard uses 1/2" tubing which can use 300 ft loop lengths, so depending on the scope of your project, you might also need additional manifolds. Warmboard also typically uses lower water temperatures.
If you'd like more information and some product comparison, we can provide that as well. We also have side-by-side thermographic video comparison if interested.