A sheet material for thermal insulation, comprising a flat core of an open-pored material having two parallel extending surfaces, and a circumferential region inter-connecting the surfaces; a first barrier film in contact with a first surface of the core and comprising a sealing layer, and a fully circumferential protrusion of the first barrier film; a flat filter material in contact with a second surface of the open-pored core and disposed oppositely first barrier film and providing a fully circumferential protrusion a second barrier film in contact with the outer face of the flat filter material and comprising at least one sealing layer facing the flat filter material, and a fully circumferential protrusion of said second barrier film; a sealing seam extending circumferentially along the protrusion of the two films and fixing the two films to each other; wherein the filter material is welded circumferentially into the sealing seam, and wherein the volume between the two barrier films and the sealing seam is sealed and evacuated; and method for producing the insulation sheet.