STAINLESS STEEL PHILLIPS COUNTERSUNK BI-METAL TEK 2 INSULATION SCREWS

Phillips Countersunk Bi-Metal Tek 2 Insulation Screws — Insulation screws do the same steel-drilling job as the standard Tek 2 drywall screw, but they're built for a completely different stack: rigid insulation board, render carrier board, or a built-up roofing liner sitting proud of the steel purlin or rail it's being fixed to, rather than plasterboard sitting hard against a stud. That extra standoff is why these are supplied longer and with a coarser thread than the drywall version - the screw has to pass cleanly through however much insulation thickness sits between the board face and the steel before the Tek 2 point even reaches its target. Typical uses are fixing insulation-backed cladding panels, external wall insulation systems, and insulated roof liners to light-gauge steel purlins and rails, almost always paired with a load-spreading washer or plate rather than driven bare. The washer or plate matters as much as the screw here: its job is to clamp the board firmly against the substrate across a wide enough area that the screw doesn't simply pull through the insulation under load, so it needs to be sized to the board thickness and the load the fixing is expected to carry, not just picked to match the screw diameter. As with every screw in this Bi-Metal Tek family, the stainless body resists long-term corrosion while a brazed-on hardened carbon-steel point does the actual drilling into steel - a solid stainless screw isn't hard enough to self-drill reliably, which is the reason this construction exists at all. Because the point rating is Tek 2, it's matched to lighter steel gauges; if the supporting purlin or rail is a heavier structural section, a Tek 2 point may not drill cleanly and a higher-rated point should be specified instead. Getting length correct - enough to clear the full insulation thickness plus solid engagement in the steel - matters more here than on any other screw in the range.

FAQs
Is the washer supplied with the screw or selected separately?
Insulation screws are commonly supplied or specified with a purpose-made load-spreading washer or plate, but its size should always be checked against the specific board thickness and fixing load rather than assumed to be a universal fit.

How does this differ from a Composite Panel Tek screw?
A composite panel screw is sized and washered for a bonded, pre-manufactured sandwich panel with metal facings either side of the core; this insulation screw is for separate insulation board or liner fixed against a facing panel, so length and washer arrangement differ accordingly.

Can this be used on a timber substrate instead of steel?
The Tek 2 point is built to self-drill into steel; on a timber substrate, a woodscrew or general-purpose fixing without a self-drilling point is the more suitable choice.