Total Contractor talks self-drilling fasteners, the importance of correct installation and how to ensure a safe and secure fix with Jon Knaggs, Technical Advisor, EJOT Applitec.
TC: At Contractor’s Day 2019, you were focusing on the issue of correct installation of self-drilling fasteners. Why is this such a big problem for the roofing and cladding sectors?
JK: Correct installation of fasteners is key to getting lifetime performance from your metal panels. Installed correctly, technical fixing and fastening products are building components that have been engineered in their own right to provide high-strength load performance, safe and secure joints, environmental longevity and countless other application benefits.
TC: So how do installations go wrong? I take it it’s not as simple as just drilling the fixing into the substrate…
JK: No, definitely not… With particular reference to the deployment of technical roofing fasteners, best practice also implies the need for roofing contractors to see the entire installation process through. Yet this can easily break down if everyone actively involved in the chain is not fully aware of the technical properties that a modern roofing fastener is engineered or re-engineered to deliver. It’s often down to the wrong choice of tools. Choosing the wrong installation tool is an easy mistake to make. Technical fasteners are engineered to seal at the head, thread and the sheet so a standard drill driver, for example, will only give you 800 revolutions per minute which is too low to properly drill the hole; in contrast a dry lining gun can turn at over 4,000 revolutions and will burn out the fastener’s drill point; impact drivers use a hammer action – great for high torque installation of anchors, but completely the wrong tool for self-drilling fasteners.
TC: So, what’s the answer?
JK: The majority of the tools mentioned above have no clutch mechanism to safeguard against over-driving and whilst it may be possible to achieve a correctly installed fastener using such a device, it can be argued that at best the installer is likely to be doing so by sensory perception – which cannot be relied upon across the installation of several thousand fasteners.
With this in mind, we use the FEIN AS CS 6.3 cordless screw gun but there are plenty of comparable guns available in battery and 110V format. They give the installer the ideal operating speed of between 1500 and 2000 rpm needed for specially engineered self-drilling fasteners to create a safe and secure fix.
TC: Describe a ‘safe and secure fix’…
JK: A safe and secure fix means the correct thread engagement into the metal thickness you’re installing into and the correct washer engagement to create a full seal. That means setting the depth the right way, and this easy to use nosepiece will give you all the help you need. The depth setting can be changed appropriately to suit the material you are fixing into and the fastener needs to be perpendicular to the substrate. What you’re looking for is a ‘bulging’ compression of the EPDM without forcing the washer to be flat, and providing you’re using the right tools and following a few important guidelines, installation the right way is a straight-forward process.
Undersetting the nosepiece will result in little or no compression of the washer and therefore no seal, whilst oversetting the nosepiece can result in the fastener stripping out its substrate – this means no seal and thread engagement is dramatically reduced.
TC: Where can readers find further information to assist them?
JK: Seeing first-hand evidence the varying levels of awareness relating to fixings and fastenings, we have produced the first in what is planned to be a series of technical guides in video and printed format in which our technical wing EJOT-Applitec review best installation practices relating to self-drilling fasteners. The Applitec guide also illustrates how to achieve correct settings that relate directly to the different type of the materials being joined, the easiest way to achieve successful application, and finally how to monitor safe and correct installation throughout the project’s schedule.
The information we are producing here shows that we don’t just sell fastening products. We are on many levels working alongside other genuine manufacturers to develop well researched technical information and to supplement with greater depth the contributions we all make to information circulated by recognised industry flag bearers such as the NFRC and the MCRMA.