Cut Edge Corrosion Treatment for Metal Cladding Explained

What Is Cut-Edge Corrosion?

When metal cladding sheets are cut to size during manufacture or installation, the exposed edge loses its protective coating. Over time, weather attacks that edge, and rust creeps back under the coating, lifting and staining the panel. It is one of the most common reasons commercial cladding looks like it needs replacing.

It usually shows first along the bottom edge of sheeting, around laps, and at gutter lines, where water sits longest. Because the rust travels underneath the existing coating, the damage is often wider than it looks from the ground.

Why You Should Not Ignore It

• Corrosion spreads under the existing coating if left untreated
• Stained, streaked panels damage a building's appearance
• Water tracking behind the coating can reach fixings and structure
• Left long enough, panels fail and replacement becomes the only option

How On-Site Treatment Works

As part of our cladding spraying service, the affected edges are restored in place, with no need to remove panels. The sequence is what makes it last:

• Clean and decontaminate the edge to remove salts, dirt, and loose material
• Remove failed coating and corrosion back to a sound surface
• Apply a corrosion-inhibiting primer to the prepared edge
• Seal the edge with a protective coating system matched to the elevation
• Blend the finish into the surrounding panel for a consistent appearance

Treat Early, Combine With a Respray

Treating cut-edge corrosion early is far cheaper than re-cladding. Combined with a full elevation respray, it restores the building and resets the maintenance clock. See our cladding costs vs replacement guide for how the figures compare.

How Long the Repair Lasts

Treated and sealed correctly, the repaired edges carry the same protection as the rest of a freshly coated elevation, which is built to last 10 years or more and is backed by a written guarantee on qualifying projects. Catching it at the staining stage, before panels distort, is the difference between a coating job and a replacement bill.

How It Fits Into Planned Maintenance

Cut-edge corrosion rarely arrives on its own. By the time the edges are staining, the wider elevation has usually lost colour and gloss too, so the most cost-effective approach is to treat the corrosion and respray the elevation in the same visit. That way the access equipment is only hired once, the whole building looks consistent afterwards, and the maintenance clock resets across the elevation rather than just at the repaired edges. For facilities managers, folding edge treatment into a planned recoat is far easier to budget than reacting to panel failure later.

It also protects the asset. Once water tracks behind the coating and reaches fixings or the structure, the cost and complexity of putting it right climb quickly. Catching corrosion while it is still a surface problem keeps it a maintenance line item rather than a capital project.

Frequently Asked Questions

What causes cut-edge corrosion in the first place?

The cut edge of a coil-coated sheet has no factory coating, so once it is exposed to weather the bare metal begins to rust. It is a normal consequence of how cladding is cut and fixed, not a sign of a faulty building.

Can you treat it without replacing panels?

Yes, that is the point of on-site treatment. As long as the panel is still sound, the edge is cleaned, treated, and sealed in place, so there is no strip-out and no waste stream.

How do I know if my cladding has it?

Look for orange or brown staining and lifting along panel edges, laps, and gutter lines. A site survey confirms how far it has travelled under the coating, which is often more than is visible.

Get an Assessment

We assess corrosion across commercial sites in Hampshire. Contact Newlook Protective Coatings to book a survey.