Warmboard Offers Subfloor Approach to Radiant Heating

Warmboard is easier to install, unlike previous systems that run tubing between the floor joists — "like lacing up a big sneaker with a really inflexible shoelace," Terry Alsberg says.

"We get lots and lots of calls from people who just want to heat a room. That's not us. We tell them to go with companies like NuHeat or Orbit if they are looking to heat the kitchen tiles. We're happy not to have that business," says Terry Alsberg, CEO and inventor of the California-based Warmboard, which makes the system.

Warmboard is radically different than electronic floor mats or hydronic systems of the past. The Romans employed hydronic systems, which used wood fires that burned in pillars, which in turn distributed hot flue gasses that ran horizontally underneath the stone slab floors. "The problem with those systems the Romans used was that they couldn't possibly heat the floor at a constant temperature, no matter how hard you beat the slaves," says Alsberg.

Equally erroneous were the systems developed after WWII used in the two Levittowns and in Joseph Eichler's communities in the Bay Area. Those projects showed how the staple-up, pipe-under-slab method of hydronic flooring used then didn't work well. Black iron (or copper) pipes fed hot water, nestled in concrete slabs, throughout the floor and walls. Not only did this slab method take a long time to heat a house, but about half of all those systems failed because once the concrete cracked, the black iron pipe underneath corroded.

Another failure was the synthetic rubber tubing called Entran II, developed by Goodyear and used by Heatway, in which a slew of systems either leaked or failed. "They say that there's no such thing as bad press, but when hydronic heating is the central article in the Wall Street Journal and it's Oprah's house in Vail that was affected, that's bad press," says Alsberg.

Rather than a staple-up method used by previous hydronic systems, Warmboard is applied the same way as any standard subfloor. "With the old way, you had to run rigid tubing between floor joists, kind of like lacing up a big sneaker with a really inflexible shoelace. And thermodynamically, it is woefully inefficient," says Alsberg.

Warmboard's APA Exposure 1-certified plywood modular panels are actually installed in place of a plywood subfloor, creating loop patterns that streamline installation down to hours.

The panels lock in place much like tongue-and-groove floor boards. "The tubing is visible during construction. There's a print a diagram right on the top of the panels with "Tubing Above: Do Not Damage" written over and over. Everything is visible right up to the point of floor covering installation. If you didn't get it right, you had your eyes closed," says Alsberg.

Another advantage of the Warmboard system is the PEX tubing used to distribute the hot water. The rigid, cross-linked plastic in PEX will not crack or degrade, the company claims.

Virtually any floor covering can be installed over Warmboard including carpet and hardwood.

Tile is installed using conventional mortar bed or backer board techniques. But like all radiant systems, insulation is needed underneath, and the company recommends standard R-19 fiberglass batts.

For the end user, the homeowner, the system saves time, reacting to temperature changes within 15 minutes without over- or under-heating the room. The end result is an evenly-heated floor with no cold spots.

That fact fits into Alsberg's philosophy: "Comfort is the absence of discomfort. You don't know when it's on or when it's off. I only notice my Warmboard in my house when I'm at someone else's house and the forced air system kicks in and everyone has to raise their voice a few decibels."