In 2013, when RIBDA raised concerns relating to ‘slippage’ or movement of traditional profiled sheets used in agricultural construction, EJOT UK took the call for action seriously. As a result the company is set to launch what can be called the first BAZ Screw developed specifically for the Big Six fibre cement roofing profile, so widely used for agricultural buildings. The original concern focused on the possibility that once in position, the roofing sheet is subject to natural movement created by the environment and over time, this movement may cause the hole created between the fixing and the purlin to enlarge, putting a strain on the securing washer.
Another aspect that was taken into consideration was that the top fix self-drilling fastener for fibre cement sheeting was originally developed when steel supports were between 1.5mm and 6.0mm in thickness - designed for the traditional hook bolts. Over recent years as yield strengths of steel purlins have increased the thickness has decreased, so it is now common to see purlins of 1.3mm and 1.4mm being used - in some instances as low as 1.2mm.
The EJOT team achieved their objective by careful repositioning of the fasteners ‘wings’ whilst shortening the length. The drill point and thread configuration was analysed leading to the development of a purpose designed fastener to accommodate and provide positive engagement into purlins of 1.2mm to 2mm thickness. Even the length of the fastener has been designed to ensure that the BAZ washer sits against the sheet sooner, to avoid any movement that could unduly elongate the installation hole in thinner purlins. These achievements were made through careful and extensive development work within the EJOT Applitec laboratory.
Antony Lowther of frame manufacturer AJ Lowther and Son Ltd witnessed the original tests that questioned the broad range of fixings being supplied to fix the Big Six profile. He has been amongst the first to trial EJOT’s new fastener and said "This new fixing is absolutely solid. Two years ago we were shocked to find that some fixings could be wound back out of the purlin with fingers; there is no way this fixing is going to back out.”