The sealing washer is a metal washer bonded to an EPDM rubber ring that compresses under the screw head to seal the hole against rain. As the screw is driven home, the rubber spreads over the sheet surface and around the shank, blocking water from entering the fixing point. To keep it watertight, tighten until the rubber just bulges evenly without over-compressing it, and fix through the crown or the valley according to the sheet profile.

Choose a spengler screw long enough to pass through the sheet and any spacer or insulation, then anchor at least 25 to 35 mm into a timber purlin or fully through a steel purlin. Common lengths run from around 35 mm for direct fixing up to 100 mm or more where sheeting sits over battens or insulation. Match the drill point and thread type to the substrate: fine self-drilling threads for steel, coarser threads for timber.

Spengler roofing screws are made for permanent exterior use, with a galvanised or coated carbon steel body or a stainless steel version for the highest corrosion resistance. The bonded EPDM washer stays flexible and UV-stable so the seal keeps out rain over many years on roofs and facades. For coastal, industrial or highly exposed sites, or where the screw head remains visible, stainless-capped or A2/A4 stainless screws give the best long-term protection.

The GeZu Impex range includes spengler roofing screws with a bonded sealing washer for fixing sheet metal, cladding, flashings and roofing. They are weather-resistant and leak-proof, and come in various lengths and thread types to suit fixing into timber or steel and different sheet thicknesses. Choose the length by the total material depth and the thread and drill point by whether you are fixing into wood or metal.