UNE 104-402 and NBE QB-90. The membrane consists of a first layer of POLIBREAL, a smooth aluminium interlayer and a second layer of POLIBREAL (UNE 104-402 and NBE QB-90 standards). The intermediate sheet can also be a polyester film (UNE 104-400/6).
In both single- and multi-layer systems, the separating layer between the membrane and the heavy-duty protection is a waterproof and gas-tight synthetic film.