STAINLESS STEEL ROOFING SCREWS

SPAX Sealing Screws (Roofing)

Sealing Screws, also referred to as roofing screws, fix through profiled roof sheets and similar coverings where the fixing penetrates the weatherproof layer and the hole must be sealed as the screw is driven. They carry a bonded sealing washer under a raised countersunk head, along with the T-STAR plus drive and 4CUT point, and are stocked in A2 stainless at 4.5mm diameter in lengths from 25mm to 55mm.

Materials Stocked in A2 (304-equivalent) stainless steel. The sealing washer is a bonded assembly, meaning the sealing element is captive against the underside of the head rather than being a loose washer fitted separately, so it cannot be omitted or lost during fixing.

Head and sealing The raised countersunk head seats the bonded washer squarely against the sheet surface as the screw is tightened, compressing the sealing element to close the hole around the shank. Tightening is a matter of judgement: enough to compress the washer and form the seal, not so much that the washer is crushed and extruded out from under the head, which destroys the seal rather than improving it.

Sizes 4.5mm diameter, in lengths from 25mm to 55mm, covering the common sheet and purlin combinations in light roofing work.

FAQs

How tight should a sealing screw be? Tighten until the sealing washer is visibly compressed and has spread evenly to the edge of the head, then stop. Over-tightening extrudes and damages the washer and can dish the sheet around the fixing, both of which create the leak the screw is there to prevent. If using a driver with a clutch or depth stop, set it on an offcut first.

Can I reuse a sealing screw if I have to remove it? It is better not to. Once compressed, the sealing element has taken a set and will not reliably reseal, and the hole in the sheet has already been formed. Replace with a new screw, and if the hole has enlarged, use the next size up or a proper repair fixing.

Where should roof sheet fixings be placed? Follow the sheet manufacturer's fixing pattern, which will specify whether to fix through the crown or the valley of the profile and at what spacing. That varies by profile and by wind loading, so it is a sheet specification question rather than a screw specification one.