Johannesburg-based roofing, cladding and steel frame fastener supplier Kare Industrial Suppliers has introduced a new range of ZAP fasteners designed for fixing roof sheeting to light steel battens and purlins.
Over the last few years, there has been an increase in the use of light steel battens and purlins in the roofing industry. Previously the battens were mainly used in low-cost housing projects but more recently they are also being used in domestic, commercial and industrial applications.
Selecting the correct fasteners to fix roof sheeting to light steel battens was a guessing game and normally one of three options was used. Firstly, the use of standard self-drilling screws, commonly used to fix roof sheeting to 2.5 mm cold rolled lip channel. Secondly, Type 17-point roofing screws that are designed to fix roof sheeting to timber purlins. Thirdly, multipurpose screws that can be used to fix roof sheeting to both steel and timber purlins.
Further, all three of these options can cause problems when fixing into thin gauge steel and will not result in a fixing offering decent pull-out values. The drill point of the standard self-drilling screws will drill the hole in the light steel batten too big and leave virtually no steel for the thread to tap into. The light steel batten is also too thin for the screw to actually tap a thread.
While the Type 17 cut-point on timber screws eliminates the problem of the hole in the batten being too big, the thread on timber screws is a coarse thread and the distance between the threads is greater than the thickness of the batten.
This results in a loose fixing which allows movement of the batten in-between the threads. Multipurpose screws compromise between timber and steel drill points and threads to make them suitable for fixing into timber and steel purlins. The coarse thread configuration, as with Type 17 timber screws, is not suitable for light steel purlins.
In addition, most of these screws are only available in Class 3 and 4 coatings making them too expensive for low-cost housing applications. The multipurpose screws are also not available with wafer heads for concealed fix applications.
In response to the abovementioned challenges, Kare Industrial Suppliers developed a range of ZAP fasteners that consists of a M6X38 mm Hex flange head and a M6X60 mm flange head, both seals for fixing corrugated and inverted box rib steel, and a M6X38 mm Hex flange head and M6X60 mm Hex flange head, also with seals, for fixing concealed fix roofing systems.
The fasteners are available with a SANS1273 Class 2 electroplated finish or a SANS1273 Class 3 mechanically coated finish. These coating options make the ZAP screws an economical option for many roofing applications ranging from fixing galvanised roof sheeting in low-cost housing applications to fixing zinc/aluminum and prepainted sheeting in moderate industrial and marine environments.
The correlation between the drill points and the thread diameter on these ZAP fasteners translates into high pull-out values, which, combined with the buttress thread configuration, ensures a safe and secure fixing.