| 摘要 |
A fastener assembly including a screw threaded fastener which has a rigid expander positioned around its shank below the head. A resilient washer having an outwardly directed flange is then provided on the fastener shank and the assembly is completed by a rigid spacer. In use, the fastener is applied to secure a roofing sheet for example to a purlin with the spacer supporting the sheet away from the purlin so as to accommodate relatively soft insulation material disposed between. The expander is forced into the sealing washer during tightening of the fastener to form a water tight seal. |
