Get the Perfect Result with Self-Drilling Fasteners

KNOWING HOW to correctly install roofing and facades using self-drilling fasteners is the key to delivering lasting quality in the building envelope – and ensuring your client’s investment is protected.

To explain why, it is important to think about how individual fixing points have the potential to undermine the overall performance of a building envelope. The NFRC highlights the need for installation best practice in its Blue Book, pointing out that the whole project team has a collective responsibility – the designer/specifier, sheeting contractor and the on-site operative – to get it right.

Hence why adopting EJOT’s best practice for using self-drilling fasteners is important – as is the need to establish a frequency and process for checking the quality of the seal between the washer and component being installed, at individual fixing points.

View EJOT’s best practice guide here.

The Main Causes of Self-Drilling Fastener Problems

Providing the fastener specification was right in the first place, in the vast majority of EJOT’s inspections the fault can be traced back to two things:

1. The installer’s choice of screw gun
2. A potential lack of awareness that the gun must be set correctly

The good news is that it is not difficult to avoid these issues providing some simple best practice is followed on site.

Best Practice Step 1 – Use the Right Driver

As self-drilling fasteners are engineered to seal at the head, thread and sheet, the screw gun must be able to operate within the required speed range and prevent thread stripping or overdriving.

Don’t be tempted to use the same driver for multiple different purposes – doing so will quickly mean you run into problems.

A drill driver will only give 800 revolutions per minute – this is too low to properly drill the hole. At the other end of the scale is a dry lining gun, which can turn at over 4,000 revs – too fast and it will burn out the fastener’s drill point.

And to be avoided at all costs are impact drivers. The rotational impact of these may be great for high torque installation of anchors, but completely wrong for self-drilling fasteners.

The majority of the drivers also have no clutch mechanism – this is really important to safeguard against over-driving. Whilst it may be possible to correctly install a fastener using a clutch-less device, most likely by sensory perception, this cannot be relied upon across the installation of several thousand fasteners. The potential for human error is always going to be there!

EJOT recommends a screw gun that can be carefully set and controlled i.e., a driver with a clutch mechanism. The ideal driver operating speed for self-drilling fasteners is between 1500 and 2000 rpm and there are plenty of screw guns that fit these criteria.

Best Practice Step 2 – Use a Nosepiece for the Driver

A ‘safe and secure’ fix requires the correct thread engagement into the metal thickness you are installing into and the right washer engagement to create a good seal. That means setting the depth the right way – and you can do this easier by using a nosepiece.

A nosepiece needs to be set depending on the material you are drilling into. If the nosepiece is underset, it will result in little or no compression of the nosepiece and no seal. Oversetting the nosepiece will result in the fastener threading out – this means no seal and thread engagement gone.

For optimum thread engagement, the fastener should be drilled straight at a 90-degree angle to the sheet. You are also looking for a nice compression of the EPDM, which compresses into the gap between the metal washer and the nylon head with a sufficient spread/bulge to create an effective seal.

Using a correctly set nosepiece will help you get the ideal insertion. Simple, but effective, this gives installers a big helping hand to achieve a consistent result.

Best Practice Step 3 – Test the Seal

Having ascertained the correct screw gun and nosepiece setting, however, it is easy to overlook the value of regular seal testing in order to be sure the optimum settings are being maintained.

How you do this, and at what frequency, has to be judged on a project-by-project basis. This is because, with so many variables affecting the quality of individual installations, it is difficult for the industry’s leading trade bodies to arrive at a ‘one size fits all’ recommendation for seal testing.

With that in mind, EJOT is soon to launch a new ‘how to’ video, in conjunction with its extended Best Practice literature, with the objective of providing a framework of recommendations that underline the value of regular and correct seal testing.

The video will cover all of the seal testing operating basics such as marrying the correct suction cup to the right fastener and washer, through to what the correct gauge reading results should be.

The resources will also offer some sound troubleshooting advice by highlighting some of the typical ‘bad practice’ workarounds known to be used on site when a fastener seal is not as it should be.

Get It Right with EJOT

As a responsible OEM, EJOT wants to support installers as much as possible, particularly in areas like seal testing where the requirements will vary by project. That’s why its latest guidance for self-drilling fasteners enables installers to develop an effective process for installation and get into a seal testing regime – best practice that ultimately delivers what the ‘right result’ should be and supports the longevity of project investment.

To find out more about installation and seal testing best practice for self-drilling fasteners, contact EJOT UK on 01977 687040, email info@ejot.co.uk or visit the EJOT website.

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