A fastener for retaining sheet cladding, such as roof or wall sheeting, with outstanding flange joints, comprising an anchoring portion intended for attachment to a substructure, either directly to it or via an anchoring plate, and a fastening portion lying generally at right angles to the anchoring portion, which is intended to be united with the outstanding flange of the sheet. The attaching portion is made in hard-rolled thin sheet with a thickness of 0.15 mm or thinner, so that it can be seam-welded to the outstanding flanges in conjunction with welding these together without the continuity of the welding seam being broken, and the anchoring portion is reinforced by means of a doubling plate which preferably lies exterior to the anchoring portion.