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.
Since flat profiled polycarbonate sheets such as Solid Flat, Solid Embossed, and Hollow profiles are normally fixed in, or on top of frames, and which the screws required are more directed towards fixing the frame itself and seldom, if ever, come in contact with the actual polycarbonate sheets; this article will focus on how to choose screws for polycarbonate corrugated profile roofing 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 I0mm 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 center, 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 screw over run or over drive. This is the 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.
Fast and Efficient Screws for Polycarbonate Roofing: Poly-Fast™ and PolyXpand™
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 – Poly-Fast™ and PolyXpand™, as detailed in the subsequent sections. These types of fasteners are meticulously designed to overcome obstacles from executing standard practices and can now effortlessly achieve a successful and long-lasting polycarbonate roofing installation.
Poly-Fast™ and PolyXpand™ fasteners were invented and designed for affixing to an underlying structure, in most cases steel purlins and battens, architectural sheet profiles made from materials which have a high coefficient of thermal expansion; in short – all kinds of plastic profiles. It is especially useful with roofing profiles made from non-metallic roofing profiles such as those made from polycarbonate, PVC or fiberglass reinforced polyester resin.
During the drill and drive process, the cutting saw on Poly-Fast™ and the drilling-tip wings on PolyXpand™ both create an 11mm diameter thermal expansion hole, which is then completely covered by the extremely durable Domed Weatherseal EPDM washer to create a perfect seal against the elements.
To prevent damage from overdriving screws and damaging the sheets underneath, Poly-Fast™ polycarbonate screws have an additional knurling on the shaft right after the threads. Normally, knurls on metal roofing screws act as a brush to clear off excess swarf created during the drill and drive process. On Poly-Fast fasteners however, the Depth Stop Knurl acts as a stopper for the thermal expansion hole cutter, the height at where it stops upon coming in contact with the purlins, which is designed to match the depth of VULCAN polycarbonate ROMA and GRECA profiles; enough so that it provides a perfect seal on the enlarged hole, but not deform the corrugations.
When working with PolyXpand™ fasteners, it is absolutely critical to drive the screw perpendicular to the sheets, and not to the point that the washer is squished, which will result in the Domed Weatherseal EPDM washer losing its flexibility, and a gaping hole gouged out by the hex washer flange.
A large Domed Weatherseal EPDM washer with two concentric sealing rims on the washer underside completes the package –
- The domed structure provides superior strength against high winds.
- Two concentric sealing rims hold the 11mm Thermal Expansion Hole Cutter in place prior to drilling, and keep the expansion hole fully sealed after installation.
The Perfect Screws for Polycarbonate Roofing
Attaining expertise in the practice of using screws for polycarbonate roofing is a journey of precision and innovation. The challenges posed by thermal expansion and over-tightening have driven the development of advanced solutions like Poly-Fast™ and PolyXpand™ fasteners. These clever tools, designed to handle thermal expansion and prevent damage, are key to achieving a secure and long-lasting polycarbonate roofing installation.Adopting these screws for polycarbonate roofing ensure a smooth installation process that maintains the integrity of your roofing projects while extending their lifespan.
VULCAN accessories are designed to work seamlessly with VULCAN Polycarbonate sheets. Consult VULCAN or your local dealer before using any non-conforming accessories. Failure to do so could result in damaging VULCAN Polycarbonate sheets and void warranty.