Drill screw

摘要

The invention provides a screw for use particularly in fastening ribbed sheeting - such as roof sheeting, and especially roof sheeting made of plastic material - to a support such as a purlin wherein the screw has means for forming an enlarged hole in the sheeting so as to permit relative movement between the sheeting and the support due to thermal expansion and contraction. The screw has a shank, a head at one end of the shank, screw threads on an intermediate part of the shank, and between the head and part at least of the screw threads at least one outwardly extending wing member operable to enlarge a hole previously formed in the sheeting to allow the screw-threaded part of the shank to be fitted therethrough. This screw is preferably a drill-point, thread-cutting screw and the wing means are adapted to form in the sheet an enlarged hole large enough to permit relative movement as between the sheet and the support due to thermal expansion and contraction of the members.