Fixing screw for roofing insulation incorporates hexagonal drive head with self tapping point and captive washer

摘要

The roofing insulation screw consists of a rod with a thread (7) surmounted by a hexagonal drive head (3). The rod (5) has a retaining section (9) for the retention of a dished washer (2). The thread in this area (9) supporting the washer, has a notched section (11) on the lower thread (10), towards the point (6), incorporating a stop (13) on the lower side (12) of this thread.