Abstract: The outer cladding of a web of a building is provided by a plurality of panels extending vertically and horizontally thereof in an array. The panels are formed along a pair of opposite vertically extending edge regions with sheet metal flanges each provided with at least one dog-legged cut-out leading to a circular section in which a screw threaded rotatable member is located. The rotatable member has passed up through a narrow vertical section of the cut-out owing to its then being oriented so that parallel flat surfaces offering a narrow cross-section are vertical and has been rotated to extend across the diameter of the circular section and then bite into the sheet metal. The panel is rendered immobile in this way and thus largely incapable of generating noise as a result of absence of capacity for movement. The flanges and rotatable members can similarly be used wherever it is desired to fix a panel or to couple two or more panels together.