How to fix rusty multiclad wall cladding sheets?

tomgg

Hi, I have rust along the bottom of garage wall cladding, but want to avoid replacing the whole sheets if possible. I was thinking of cutting below the fixings about 1.5m up, and sliding in a 1.6m sheet behind, leaving an overlap. Are there any major problems with that approach? Picture Shows worst of the rust, alongside a just poured slab for a water-tank, so want to at least repair these before the tank goes in.

MitchellMc

HI @tomgg,

It looks like surface rust at this stage rather than anything structural. Multiclad is pretty resilient, so you’ve likely still got quite a few years before it deteriorates to the point of pin-holing or losing integrity.

If you’re looking to slow or stop it, the usual approach is:

• Remove as much of the loose surface rust as possible (wire brush or wire wheel works well)
• Apply a rust converter to stabilise what’s left
• Prime the area
• Apply a topcoat paint.

That process seals the steel back up and helps keep moisture out, which is what drives the rusting in the first place.

Given you’ve just poured a slab there, it’d also be worth running a bead of Sikaflex (or similar) along the bottom edge of the sheeting. That helps stop water wicking up from the slab and sitting under the edge, which is often what causes this kind of rust to begin with.

Your idea of cutting the sheets and slipping a new section in behind could work in theory, but I haven’t actually seen it done in practice. The main unknowns would be how well it sheds water at the overlap and whether it introduces any long-term issues (like trapping moisture), so I can’t say for sure if there’d be downsides.

Please let me know if you have any questions.

Mitchell