Patent AT-E400711-T1: [Translated] MULTI-LAYER MATERIAL, ESPECIALLY FOR USE AS A SUB-ROOF

A water vapour permeable laminate (16), especially for use as underroofing or underslating for roofs. The laminate comprises an outer layer (18) that is formed by a perforated first film or foil, and an inner layer (19) which has at least some areas formed by a second, non-perforated film of the type having a water vapour diffusion resistance, which varies in dependency of the relative humidity of air in contact therewith. Thus, the vapour diffusion resistance is reduced, when the relative humidity increases, and vice versa, and the laminate is characterised in that the water vapour diffusion resistance of the outer layer (18) substantially exceeds the maximum water vapour resistance of the second film (19).