Daemmplatte aus nicht extrudiertem Hartschaumstoff fuer ein Umkehr-Dach

The invention relates to an insulation panel made of rigid foam for building a reverse roof (R roof), said insulation panel consisting of non-extruded, thermoplastic rigid foam and whereby at least one surface of the insulation panel is modified in such a way that said surface has a water vapour diffusion resistance greater than the core material of the insulation panel.