STAINLESS STEEL HEXALOBULAR BUTTON BI-METAL TEK 2 STITCHING SCREWS WITH 12MM SEALING WASHER

Hexalobular Button Bi-Metal Tek 2 Stitching Screws with 12mm Sealing Washer — Stitching screws don't fix a sheet to the structure at all - their job is to join one profiled sheet to the next along a side lap, which is why the Tek 2 point on this screw only ever has to drill through two thin layers of overlapping roofing or cladding sheet rather than into a purlin or rail. The low-profile button head sits close to the sheet with minimal projection so it doesn't snag or catch, and the hexalobular drive gives a firm, low-cam-out engagement that matters when driving large numbers of these along a lap line. A 12mm bonded washer seals each stitching point against wind-driven rain finding its way under the lap. Applications are almost entirely roofing and wall cladding side-lap jointing on profiled steel sheet buildings - industrial units, agricultural buildings, and similar built-up steel envelopes - rather than general construction fixing. Bi-metal construction applies here as everywhere in the Tek range: a stainless body and thread resist weathering over the building's life, while the brazed hardened point is what lets the screw self-drill the two sheet layers without a pilot hole. Because the point only has to get through thin sheet rather than structural steel, Tek 2 is the point rating used across the whole stitching-screw family rather than stepping up to Tek 3 or Tek 5, which exist for thicker single-skin or structural fixings. Where this range differs from the rest of the Tek 2 family is head type and washer size - choosing the button-head hexalobular version over the hex-head equivalent with a 16mm washer comes down to whether a lower-profile finish or a driver preference for hexalobular over a socket matters more for the installation, since both share identical drilling and jointing performance.

FAQs
How far apart should stitching screws be spaced along a side lap?
Spacing is set by the sheet manufacturer's fixing guide or the project specification, since it depends on the sheet profile and the wind loading the roof or wall is designed for, rather than a single fixed figure.

Could a Tek 3 or Tek 5 stitching screw ever be needed?
Not normally - side laps between sheets are thin regardless of the building's structural steel gauge, so Tek 2 point capacity is standard across the stitching screw family; Tek 3 and Tek 5 point ratings are reserved for screws drilling into the structure itself.

Can a stitching screw be used as a structural fixing in an emergency?
No. It lacks the drilling capacity and load rating of a structural Tek fixing, and using it in place of one risks a failed connection; always specify the correct halter or structural screw for sheet-to-structure fixing.

What's the practical difference from the hex-head 16mm washer version?
Performance is identical; the choice is head type and washer size - hexalobular button head with a 12mm washer here, versus a hex head driven by socket with a larger 16mm washer on the alternative.