Roof Handler - A Member of the Youngman Roofing Group
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Class 3 vs Class 4 Roofing Fasteners

When choosing the fasteners to secure your roofing system, it’s important that you select those that are most suitable for the particular application. Using the incorrect class of fastener can affect the manufacturer’s warranty on your sheeting and substantially shorten the lifespan of your new roof.

We are proud stockists of Corroshield® roofing fasteners, which have a high resistance to corrosion and reduce installation times thanks to their self-drilling ability. This feature enables the fasteners to drill their own hole and tap their own thread into a timber or metal substrate.

Fasteners used for securing metal roofing and cladding manufactured from zinc-aluminium coated steel or galvanised coated steel can be classified as either Class 3 or Class 4.

Class 3
Class 3 fasteners are commonly used in areas where there are moderate levels of airborne pollution or coastal areas with low salt levels. They should be able to withstand 1000 hours of salt spray/fog testing, without showing more than 5% red rust on the surface of the fastener head. As a minimum, we recommend using Class 3 fasteners with AZ150 roof sheeting material.

Class 4
Class 4 fasteners are needed in areas with discernible levels of airborne pollution or coastal areas with moderate to high salt levels. They should be able to withstand 2000 hours of salt spray/fog testing, without showing more than 5% red rust on the surface of the fastener head. We recommend using Class 4 fasteners with AZ200 roof sheeting material, although they are also suitable for securing AZ150 material due to their superior coating performance.

Both Class 3 and Class 4 fasteners need to be clearly marked for traceability and accountability purposes. However, the head markings do not necessarily have to include a number 3 or number 4.

To find out more about which class of fastener will be most suitable for securing your roofing system, please speak to one of our experts by calling 044 873 0627.

Read more about Corroshield® Fasteners by clicking here.