Can IKO Permascreed be used as a Vapour Control Layer? Yes, in warm roof systems, a minimum 13mm thick layer of IKO Permascreed laid on IKO Glass Fibre Tissue separating lauyer will act as an effective VCL. What is the asphalt specification for a walkway on a council flat? I need to render the inside of a wall. Could you advise me on the best product, with the most straightforward installation?