STAINLESS STEEL HEXAGON HEAD BI-METAL TEK 2 HALTER FIXING SCREWS WITH 16MM SEALING WASHER

Hexagon Head Bi-Metal Tek 2 Halter Fixing Screws with 16mm Sealing Washer — Halter fixing screws carry the sheet's actual fixing load into the structure, which is what separates them from the stitching screws that merely join adjacent sheets together - this is the primary connection between a roof or wall sheet and the purlin or rail underneath it, driven straight through the sheet profile via a halter or spacer system. A hex head lets a socket driver deliver more consistent torque and a firmer grip than a screwdriver bit would manage, which matters given the longer lengths and higher drilling loads this fixing sees compared with a stitching screw. The 16mm bonded sealing washer spreads clamping load over a wider area of sheet and closes the penetration against wind-driven rain, which is essential wherever the screw passes through the external weather skin of the building. This is a structural fixing for roofing and cladding on profiled steel sheet buildings - industrial, agricultural, and commercial steel-framed structures - rather than a general-purpose screw, so it should be specified as the primary sheet-to-purlin connection rather than substituted in for a stitching or general Tek 2 role. Bi-metal construction gives the stainless body and thread long-term weather resistance while the hardened point handles the actual self-drilling into the steel purlin, the same principle running through every screw in this Tek range. Tek 2 point rating matches this screw to lighter-gauge steel purlins and rails typical of halter-type cladding systems; if the supporting steelwork is a heavier section, a Tek 3 or Tek 5 hex-head screw is the correct step up rather than forcing a Tek 2 point to drill material it isn't rated for. Beyond point rating, length needs to clear the full halter or spacer stand-off plus sheet thickness and gain solid purchase in the purlin, and the washer diameter should be checked against the halter system's own guidance rather than assumed universal.

FAQs
Is the hex head interchangeable with the stitching screw's button head for this role?
No - the halter fixing screw is a structural fixing carrying the sheet's load into the purlin, and needs the higher, more consistent torque a hex head and socket driver deliver; a stitching screw's lighter construction isn't rated for that job.

What's the sign this should be upgraded to a Tek 3 or Tek 5 hex screw?
If the point stalls, overheats, or fails to complete a clean hole in the purlin, the steel is likely a heavier section than Tek 2 is rated for, and a Tek 3 or Tek 5 hex-head screw should be used instead.

Can this be used without the halter or spacer system it's named for?
Yes, wherever a Tek 2 capacity, washered hex-head screw is needed, though it's specifically sized and named for halter-type cladding systems and should be checked against the actual spacer or standoff in use.