STAINLESS STEEL HEXAGON HEAD BI-METAL TEK 5 SCREWS WITH 16MM SEALING WASHER

Hexagon Head Bi-Metal Tek 5 Screws with 16mm Sealing Washer — Take the Tek 5 point's heavy-duty drilling capacity and add a 16mm bonded sealing washer, and the result is the fixing specified wherever a roof or wall sheet needs to be fastened straight through into thick structural steel - heavier purlins, deep rail sections, or portal frame steelwork - and that connection also has to stay weathertight. The washer compresses against the sheet profile to seal the penetration against wind-driven rain, in exactly the same way as the washered Tek 3 version, but it's paired here with the longer point and flute that Tek 5 needs to self-drill and clear swarf from thicker steel without stalling or overheating partway through. As with the rest of the range, bi-metal construction is what makes this combination possible at all: the stainless body and thread give the fixing the corrosion resistance an external roof penetration needs long-term, while the hardened carbon-steel point handles the demanding job of drilling thick structural steel, well beyond what a solid stainless self-drilling point can manage. Specifying Tek 5 here rather than Tek 3 is purely a function of the steel gauge behind the sheet - this washered Tek 5 screw is for the heaviest purlins and rails in a roofing or cladding system, where a Tek 3 washered screw would struggle to drill cleanly or take excessive time to do so. Getting the point rating right matters more than almost any other spec on this screw, since an under-rated point risks a poor start, heat build-up, and a weakened or failed fixing rather than simply taking longer. Length should clear the sheet profile plus achieve solid thread engagement in the purlin, and as with any washered Tek screw, the washer needs even, full compression against the sheet once driven to maintain the weather seal it's there to provide.

FAQs
How does Tek 5 differ from Tek 3 in this washered range?
Tek 5 has a greater drilling capacity and a longer point to clear swarf from thicker steel sections, while Tek 3 is matched to medium-gauge steel; both share the same 16mm washer format for sealing an external penetration.

Does this replace the Composite Panel Tek 5 screw for insulated panels?
No - the composite panel version is specifically lengthened and sized to pass through a bonded insulated panel's core without crushing it; this standard washered Tek 5 screw is sized for single-skin sheet rather than a sandwich panel build-up.

What steel thicknesses is Tek 5 intended for?
Heavier-gauge structural steel beyond what a Tek 2 or Tek 3 point is designed to drill efficiently; the exact capacity should be checked against the manufacturer's technical data for the specific steel gauge involved.