EJOT fastener solves slippage issues for Big Six Profile roofing sheet

EJOT UK has announced the launch of the its first BAZ Screw, developed specifically for the Big Six fibre cement roofing profile widely used for agricultural buildings.

The product release follows concerns raised by RIBDA relating to slippage and movement of traditional profiled sheets used in agricultural construction.

The concern focused on the possibility that once in position, the roofing sheet is subject to natural movement created by the environment. 

It was thought that this movement may cause the gap created between the fixing and the purlin to increase, putting a strain on the securing washer.

Tests carried out at the time seemed to support the theory across a range of commonplace industry-supplied fastenings.

Another issue 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. 

In recent years it is now common to see purlins of 1.3mm and 1.4mm being used, as yield strengths of steel purlins have increased the thickness has decreased.

Kevin Rackley, product manager for EJOT UK comments: “We had a case of a common application with a problem and in need of a solution. Fastener design and development is what EJOT is all about and our R&D team were quick to run with the industry-wide challenge.”

Bespoke fastenings

WIth the aim of becoming the first manufacturer to create a bespoke solution rather than provides a ‘fits-all’ offering, EJOT carried out a series of modifications and tests on its traditional wing-drilling fastener. 

The initial phase of re-engineering concentrated on eliminating any possibility of the panel ‘jacking’ and to look at the installation holistically.

The team’s objective was achieved by repositioning the fasteners ‘wings’ whilst shortening the length. 

The drill point and thread configuration was subsequently analysed leading to the development of a purpose designed fastener to accommodate and provide positive engagement into purlins of 1.2mm to 2mm thickness.

Extensively tested

The length of the fastener has been designed to ensure that the BAZ washer sits against the sheet sooner, avoiding any movement that could unduly elongate the installation hole in thinner purlins. 

This was achieved through careful and extensive development work within the EJOT Applitec laboratory.

Pull-out test carried out in September demonstrate the fastener recording an ultimate mean performance of 3.8 KN from 1.4mm steel purlins and a 3.0 KN from 1.2mm galvanised steel purlin sections, clarifying that the fastener not only improved on the installation performance but also from a technical standpoint.

Antony Lowther, of frame manufacturer AJ Lowther and Son, witnessed the original tests that questioned the broad range of fixings being supplied to fix the Big Six profile: ”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.”

The new EJOT Baz screw will be product coded as the JT2-FZ-3-6.3 x 90 BAZ and is available from the manufacturer now.

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