STAINLESS STEEL HEXAGON HEAD BI-METAL TEK 5 SCREWS

Hexagon Head Bi-Metal Tek 5 Screws — Tek 5 is the top of the point-rating scale in this range, built for heavier structural steel sections and multiple-layer fixings that would defeat a Tek 3 point - thick purlins, cleats, and portal frame connections where the point needs a longer flute to clear swarf fast enough to keep drilling rather than clogging and stalling. Left bare without a sealing washer, this version is intended for connections that stay inside the building envelope rather than penetrating an external roof or wall skin: structural steel-to-steel fixings, bracketry, and internal connections where there's no weather seal to maintain. The bi-metal principle behind every screw in this family applies at its most demanding here - a stainless body and thread carry corrosion resistance, while the brazed hardened carbon-steel point is what makes drilling through thick or layered steel possible in a single pass, since a solid stainless self-drilling screw would blunt, overheat, or simply fail to penetrate steel at this gauge. This is exactly the scenario where reaching for the Bi-Metal Tek range over a plain stainless self-drilling screw stops being a preference and becomes a functional necessity: plain stainless points are not hardened enough to reliably self-drill heavier structural sections at all. Choosing Tek 5 over Tek 3 comes down to the steel gauge being fixed into - Tek 5's longer point and flute are matched to structural sections and multi-layer connections beyond what a Tek 3 point is designed to clear, and if a Tek 3 screw is binding, overheating, or failing to complete a clean hole on a given connection, that's the sign to move up rather than force it. Length needs to clear every layer being joined plus solid thread engagement in the final layer, and because this version carries no washer, it should only be specified where the connection sits away from the weather envelope.

FAQs
What's the practical sign that Tek 3 isn't enough and Tek 5 is needed?
A Tek 3 point that binds, overheats, or takes noticeably longer than expected to complete a hole is usually being pushed against steel heavier than it's rated for; Tek 5's longer point and flute are built to clear swarf from that heavier section instead.

Is this suitable for lighter-gauge steel as well as thick sections?
It will drill lighter steel too, but there's no benefit to using the heavier Tek 5 point where a Tek 2 or Tek 3 screw would do the job efficiently, so point rating should still be matched to the actual steel gauge rather than over-specified.

Why is there no washer on this version?
It's intended for connections that stay inside the building envelope rather than penetrating an external weather skin, so a sealing washer isn't needed; the washered Tek 5 version should be used wherever the fixing passes through an external sheet.