Abstract: A fixing device for use in fixing insulating boards and waterproof sheeting, if required, to be fixed with the insulating boards on a sheet panel forming a cover plate for a flat roof, includes a sleeve inserted into a drilled hole extending through the waterproof sheeting, the insulating board, and the sheet panel, the lower end of the sleeve projecting beyond the sheet panel and including an expandable part which is opened out beyond the drilled hole diameter by tightening a nut on a bolt which passes through a plate or disc-like abutment element and the bore of the sleeve. The fixing device is made such that it can be detached again so that the roof covering can be repaired, renewed, and reconstructed, if required, without causing significant damage to the sheet panel.

Abstract: A self-tapping screw (1) for use in fixing insulating boards (4) and waterproof sheeting (3, 3'), to a flat roof sheet panel (2), has a screw head (6), a self-drilling tip (10) and a screw shank which has a self-tapping thread (9) adjoining the self-drilling tip (10) and divided into sections (9/2, 9/3) by at least one smooth shank section (8). A further smooth shank section (7) directly adjoins the screw head (6). The diameter of the smooth shank sections (7, 8) is smaller than the root diameter of the self-tapping thread (9), and the end (15) of each thread section nearest the screw head (6), extends radially inwardly to the screw-shank diameter in the form of a flat radial surface (16) which is free of a thread run-out and is perpendicular to the axis of the screw shank. The screw (1) provides greater reliability against being unintentionally slackened, released and pulled out of its anchorage hole under the typical stresses experienced by flat roofs.