Yes, a kind of carrier layer such as Fermacell, OSB boards or Mi-board has to be laid over the heating foil. This carrier layer has the function of mechanically protecting the carbon heating foil and absorbing the infrared rays as a heat transfer medium and distributing the heat evenly. The thermal resistance of the entire structure has to be considered. This must not exceed a value of Rλ = 0.15 (m²K)/W.