STAINLESS STEEL HEXALOBULAR RAISED COUNTERSUNK WOODSCREWS 15MM SEALING WASHER

Hexalobular Raised Countersunk Woodscrews 15mm Sealing Washer — This is the hexalobular equivalent of the smallest sealing washer option in the raised countersunk range, built for exactly the same job — sealing the fixing point on exterior timber boards such as fascia, soffit, and cladding, where the bonded washer compresses under the head as the screw is driven and closes the gap around the clearance hole against water ingress. The head geometry, washer material, and 15mm diameter are identical to the Pozidriv version; what changes is the drive. A hexalobular (Torx-type) recess has more contact points with the driver bit than Pozidriv, giving noticeably better resistance to cam-out under sustained or high torque, which is exactly the condition created by driving large numbers of these screws with a powered site driver across a cladding or fascia run — the practical reason to pick this version over its Pozi counterpart. At 15mm, the washer suits smaller clearance holes and thinner boards, giving the least visually prominent finish of the three sizes in this range; where boards are thicker or holes larger, the 20mm or 25mm hexalobular versions provide more sealing and bearing area. Grade selection follows standard exterior fixing logic: A2 (304-equivalent) is right for general UK weather exposure on most cladding and fascia work, while A4 (316-equivalent) is worth the extra cost on coastal buildings, cladding exposed to salt spray, or fixings near swimming pools, where its resistance to chloride pitting protects the fixing well beyond what A2 can offer in those conditions. Because these screws are typically installed in volume, sizing decisions are worth getting right up front: gauge should suit the board and fixing load, length should leave solid thread engagement in the substrate beneath the board, and washer size should be settled based on hole diameter and board thickness rather than adjusted part-way through a job.

FAQs
How does this differ from the Pozi version with a 15mm washer?
Only the drive changes — hexalobular gives better resistance to cam-out and higher torque transfer than Pozidriv, which is the main reason to choose it for powered, high-volume driving.

Why would hexalobular matter more here than on an indoor fixing?
Exterior board fixing is typically done in volume and often with a powered site driver, where sustained torque and repeated use are far more likely to cause a Pozidriv bit to cam out than on occasional indoor screws driven by hand.

What board thicknesses suit the 15mm washer best?
Thinner boards and smaller clearance holes, where a wider washer would be unnecessary and more visually prominent than needed — thicker boards or larger holes are better served by the 20mm or 25mm washer in this range.

Does the hexalobular drive change how the sealing washer performs?
No — the washer's sealing function depends on the washer material and how well it compresses under the head, which is unaffected by drive type; hexalobular only changes how reliably the screw can be driven.