Radiant heat tubes in a concrete slab, I can say from personal experience in my own home, are the perfect heating system. Most radiant heat tubes are tied to the wire mesh in whatever pattern the plumber feels like following before the slab is placed. But Thermo-Snap is a better alternative. Not only does it provide the perfect way to get the heat tubes where you want them, it also insulates beneath the slab, providing an R-value over 8. This material comes in 16 psi or 25 psi versions (for heavier live loads). Go to http://benchmarkfoam.com for more information.