Abstract: A panel for self-supporting roof structures of extruded profile elements having at least one main duct closed at the ends with closing members (10) which are made of plastics material and have the same profile as the profile elements and is closed at one end (17). The closing member (10) is of so reduced dimensions as to fit into any main duct in the profile element while allowing some air exchange without the risk of penetration of dirt.The closing member (10) has preferably resilient sealing flaps (12, 13, 14, 15) on two opposite sides, so that one and the same member (10) can be used for closing profile elements of varying size and shape, e.g. as a result of manufacturing inaccuracies. A V-shaped groove encircles the outer surface of the closing member and permits movement of the two parts of a bipartite flap.

Abstract: A hollow panel of extruded plastics for walls and roof structures and having at least two main ducts separated by a secondary duct divided into three or more subducts, one of which is dimensioned so as to accommodate an anchor bar intended for absorbing upwardly directed wind pressure. Each of the main ducts is divided into two channels by a thinner intermediate wall extending through the secondary duct or ducts.A self-supporting arcuate roof comprising such panels provided with coupling members forming together locking ducts wherein locking wedges or reinforcing bands of metal are inserted.The subducts of the panels are designed to resist pressure and torsional forces without separate reinforcing elements.