Roofing Screw Selection: Sheet, Deck, Point and Washer

The screw suits both decks

Roofing screws work whether the roof structure is iron steel or wood — in both cases the screw drills and tightens immediately. What changes is the point and the thread form, not the product family.

The 1mm line

Where the iron sheet is less than 1mm thick, use a self tapping roofing screw. Over 1mm, use the self drilling version. This single number resolves most roofing screw enquiries.

Sealing the penetration

Every roof fixing is a hole in the weatherproof layer. A bonded EPDM washer seals it — EPDM because it holds up to ultraviolet and ozone where cheaper elastomers harden and crack. Outside diameters of 14mm, 16mm and 19mm cover the normal profiles; which one you need follows the sheet profile and where the fixing lands on it.

Hiding the fixing

Three routes: a painted head and washer finished to the sheet colour, a moulded nylon cap fitted over the driven head, or a plastic washer cap. The cap covers the head; it does not replace the sealing washer, and the two are normally used together.

Head and drive

Hex washer head is the default because it cannot cam out — which matters when the driver is held above head height at arm's length. The head sizes correspond to #6, #8, #10, #12 and #14 nut setters.

Everything on this page describes the specification range Beyond Industry Groups Limited works to. Where a figure is a laboratory test result rather than a service life, it is described as such.