October 27, 2025 G Thom

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As with fixing all types of roofing material, there are certain guidelines to follow on how to screw polycarbonate roofing, some of which; are rules that work in general, and others which are specific to polycarbonate sheets.

Challenges in Using Screws for Polycarbonate Roofing

Dealing with screws for polycarbonate roofing poses a significant challenge due to the material’s relatively high coefficient of thermal expansion. Current industry practice is to ream a hole in a non-metallic roofing profile to install a #12 (4.5mm diameter) screw. This requires two tools, two operations and a reasonable amount of time, effort and skill. It is a significant time-consuming procedure. Oftentimes, screws are positioned at one side of the hole, instead of in the centre, which can result in insufficient clearance for expansion in the relevant direction.

Another challenge encountered during the installation of sheet roofing profiles involves issues with screws for polycarbonate roofing, specifically the problem of over-tightening of fixing screws such that there is a squashing of the raised profile through which the screw is passed. It is quite common for even professional installers to overdrive a fastening screw, squashing the relevant ridge in the profile, and requiring them to reverse the screw rotation in a secondary operation to bring it to the correct position. Not only does this procedure take more time than necessary, but it may also damage the sheets.

The Art…..

To comprehend the art of fixing polycarbonate roofing, familiarizing oneself with techniques that account for thermal expansion and counteract over-tightening was standard practice. Dive into the realm of advanced fastener choices, such as screws for polycarbonate roofing – the ZAP S/D Polycarb Screw. These fasteners are meticulously designed to overcome installation obstacles.

Our polycarb fasteners were invented and designed for affixing to an underlying structure, in most cases steel and/or timber purlins and battens.

During the drill and drive process, the winged shaft creates an expansion hole, which is then completely covered by the extremely durable and pliable BAZ EPDM washer.

When working with our Polycarb Fasteners it is absolutely critical to drive the screw perpendicular to the sheets, and not to the point that the washer is squished.