What is cut edge corrosion and what damage can it do?

Cut edge corrosion occurs on metal sheets. When metal cladding is manufactured the corrugated sheets are coated in a plastic material such as Plastisol. This coating prevents the underlying metal from being corroded by the elements and improves its appearance. After the cladding is cut to size in a factory the cut edge has no coated protection and the metal is exposed. Once the cladding is used in construction this can lead to cut edge corrosion.

Cut edge corrosion starts when the metal sheets are then attached to a roof or elevation of a building. As the steel edges are exposed to oxygen they are prone to corrosion which is exacerbated by water and pollutants. Over time the factory coating can then peel back from the uncovered edges.

Locating cut edge corrosion

Cut edge corrosion is usually found around the edges of metal sheets where they overlap and at the eave edges. Horizontal overlaps are particularly vulnerable to this type of deterioration. Even though cut edge corrosion usually begins around edges it gathers speed through capillary water action and can spread quickly.

Metal guttering can also suffer from cut edge corrosion. If gutters are poorly fitted or blocked by debris the damp can then penetrate through exposed metal edges to other parts of the building. This can lead to structural weakness and further cut edge corrosion on other panels or cladding.

The effects of water

If cut edge corrosion is left untreated, the original protective coating also continues to peel away from the metal surface. This allows more water to penetrate the metal and leads to rust. Without the protection of an intact coating, rust can quickly eat away at the cladding. This makes it brittle and resulting in leaks and water damage which can affect both the aesthetic and structural integrity of the building. In some circumstances if the damage is quite severe, the metal cladding can become perforated and very expensive to repair, therefore the sooner cut edge corrosion is treated, the better.

Repairing cut edge corrosion protects cladding from the elements as well as reducing the extent of the peeling back of the coating. Protecting the cut edge on cladding provides a better seal on the horizontal lap and lap joints. If done professionally, repair work will not only protect the structure of the building but improve the look of the building too.

This answer is a guide only. Further advice should be sought regarding cut edge corrosion. Jones Melling has a team of specialists who can advise you on the best course of action regarding your property.

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