I know slab foam rubber pads from Foamex and Sponge Cushion are recommended for use over warmboard, but I'd like to know if anybody has actually purchased a specific line of pad from one of these companies for use over warmboard? 1. What was the name of the pad (SCI has several different lines, in different thicknesses)? 2. Where did you order from (SCI referred me to a distributor who referred me to a retailer - none of whom new anything about radiant floors, and shipping was pretty steep)? 3. Are any of these slab foam pad products available through a home center? Thanks

Ergnut: The Warmboard web site listing is not comprehensive, neither is foam pad the only type you can use. It is the best approach for heat transfer reasons, but you have a wide selection of pads that can be used over Warmboard. The caveats:

Avoid rubber that has clay in the mix.
Avoid rebond (any thickness).
Both of these tend to break down faster than most and heat makes it worse.

Nearly anything else is fair game, but be sure to note the R-value of the one you select. It will effect the water temperature settings some.

Give Warmboard a call at 877-338-5493. The technical staff is pretty informed on such matters - sometimes much more than the floor covering people themselves (as you just found out).

Barry E. LaDuke
Warmboard, Inc.
Northwest Regional Manager

I just got this response from Foamex about the slab foam rubber (which is recommended by Warmboard): Thank you for visiting FXI on the web. FXI no longer manufactures slab foam rubber pad. If interested you can use a rebond product, with a low R value. I hope this information is helpful.