We manage a warehouse with profiled steel cladding and over the last year we've noticed orange streaks running down the faces of the panels. The main sheet surfaces still look sound to me, so I'm not sure where the rust is actually coming from. Any idea what's going on?
Staining that runs down an otherwise sound face is almost always bleeding from somewhere higher up rather than the panel itself failing. The usual culprits are corroding fixings, cut edges at the sheet ends and laps, or steel swarf left from drilling that rusts and washes down. Follow the streak to its source and you will normally find the real problem at a fastener head or an exposed edge. It is worth ruling out staining from an adjacent detail too, such as a rusting gutter or flashing above. A survey is the reliable way to pin down the origin before you spend on treatment, so it is worth booking a survey.
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