Sealing Washer

Which sealing washer?

• •EPDM sealing washer (fluted): a rubber washer that goes under the head of a #12 or #14 self-drilling screw. Hobson describes sealing washers as UV resistant and made to create a waterproof seal when fixing roof sheets or cladding with self-drilling screws. This is the everyday rubber washer for sheds, roofing, cladding and solar panel fixings.
• •Cyclone multiseal washer: Hobson describes the 25mm washer as an aluminium washer with a bonded EPDM seal, for #14 screws crest fixing metal roofing to timber or steel battens and purlins in high-wind (cyclonic) conditions. The 32mm washer is the larger multiseal washer for #14 screws.
• •Red fibre washer: a thin, firm, non-metal washer for small machine screws and fittings, from M3 to M10.
• •Nylon adhesive washer: a flat M3 nylon washer with an adhesive face, which holds it in place and stops it moving around.
• •Nylon screw insulator: a shouldered nylon washer that sits in the hole to keep a screw out of contact with the panel.
• •Render washer: a large blue washer that spreads the load of a #10 countersunk screw when fixing thermal insulated wall panels in cladding systems. A raised face and 8 reinforcing ribs stop it spinning as you drive the screw.

Sealing washer sizes

Cyclone washers and cyclonic areas

Hobson had its Universal Multi-Seal Cyclone Assembly, a 14-10 x 53mm self-drilling screw with the bonded 25mm aluminium washer, tested for static and cyclic simulated wind loads at the James Cook University Cyclone Testing Station, and produced span tables from the results that engineers use to specify the assembly. Those results are for the tested screw, washer, cladding and purlins together: Hobson publishes no rating for the washer on its own, so roofing in cyclonic regions follows the engineer's or roofing manufacturer's fixing specification.

The painted 25mm cyclone washers come in 33 Colorbond colours to match the roof, including Monument, Surfmist, Basalt, Woodland Grey, Shale Grey and Night Sky.

Fitting sealing washers

1. Use the washer that suits the screw gauge: #12 or #14 EPDM washers, #14 for cyclone washers, #10 for render washers.
2. Drive roofing screws until the seal is compressed evenly, not crushed: the roofing screws guide shows correct seal compression.
3. For render washers, Hobson's instruction is to position the washers and fix them evenly across the wall, and not to over tighten so the washer and the panel around it do not distort.

EPDM, aluminium, fibre or nylon?

• •EPDM (ethylene propylene diene monomer) rubber: the sealing material in the fluted washers and bonded to the cyclone washers.
• •Aluminium: the cyclone washer body, unpainted or painted in Colorbond colours.
• •Red fibre: a firm, thin washer for small screw sizes.
• •Nylon and polyethylene: the adhesive washer, screw insulator and render washer.

Sealing washers in Adelaide

Allmat supplies EPDM sealing washers, cyclone washers, fibre washers and the roofing and tek screws that go with them to roofers, shed builders and trade across Adelaide and South Australia. Add them to a quote with your screws and we will price the lot.

Questions