Check the flooring r-value before installing. As long as the flooring product has an r-value of 1 or less, it should work well with electric floor heating. Underlayment must be placed on the subfloor and be placed under the heating layer. For ease of installation, we strongly recommend the underlayment be at least 1/4" thick, and the heating element should be placed between the underlayment and the flooring. Do not place any underlayment between the element and the flooring.