A method of bird-proofing a metal purlin of substantially a channel or C shape. The method involves wedging a non-structural insert (1) between the lowermost flange and the internal surface (5) of the base (6). The non-structural insert is adapted to provide an inclined face preventing or deterring birds from perching on it. A lip (3) of the lowermost flange acts as a fulcrum, wherein the insert is engaged with the lip (as shown) and rotated around until an elongate portion (7) sits parallel and adjacent the internal surface (5) of the base (6). The portion (7) may flex around apex (9) to allow installation. The non-structural insert may comprise 0.4mm thick metal.
