Meaning
A progressive metal degradation begins where profiled steel cladding sheets are cut during installation. This cut edge corrosion occurs because the protective zinc coating is removed, exposing the bare steel to atmospheric moisture. The damage spreads inward and can eventually require the replacement of entire panels.
Chemical Process
Exposure to rainwater initiates galvanic action between the zinc layer and the steel base. Over time, the sacrificial zinc is depleted and red rust forms on the exposed iron. This oxidation causes the protective plastic coating to peel away from the metal.
Remedial Method
Workers scrape away the loose coating and apply a zinc-rich primer to the affected margins. A topcoat of liquid polymer then seals the repaired area against further atmospheric contact. This process must be done in dry conditions to ensure long-term paint adhesion.
Contractors apply a specialized sealant to the bare edge of the metal sheets to re-establish the protective barrier before cut edge corrosion can travel up the sheet.
Cladding Life
Early intervention prevents the rust from penetrating deep into the overlap joints of the roof. If the damage extends too far, the structural capacity of the sheet is compromised. Neglecting this maintenance leads to internal water damage and costly structural repairs.