What type of flooring is 2nd best over radiant floor heat?

What is best? Well, it is a fit between efficiency and comfort.

You can cover a radiant floor with practically anything, but generally less is more.

Bare concrete will transfer heat at the lowest design water temperature,followed by vinyl, tile, engineered wood, marble, engineered bamboo, oak, maple, thin carpet and pad and cork in typical installed thicknesses.

Low design temperatures mean lower fuel bills, especially when a condensing boiler is used as the heat source.

Most suppliers will have an R value for their product which is a critical design detail that must be determined before starting any radiant floor design.