Installation into the slab is preferred, because it makes the heating unit more efficient. The installer staples up radiant heating units underneath floor joists. With this type of installation, the temperature on the floor is a factor, especially in homes where the installation has to work with specific types of existing flooring. A wood floor for example can be susceptible to high temperatures, possibly causing the floor to buckle warp or even split. Wood floors cannot be exposed to little more that eighty degrees Fahrenheit.
Laminated floors can take a little more heat but only by a few degrees.
Installers should consult with floor manufactures as to how much heat they can actually allow on the flooring in their homes. Wood flooring must be seasoned and any possible moisture must be taken out, in order not to damage the flooring itself. The flow of air circulation produces more dust and debris, which makes air-purification difficult. With a radiant floor, you don t have any air movement per say. You are eliminating the air process, which solves the asthma factor.