Corrosion: red rust on galvanised mild steel cladding
Listed under: Exterior, finishes, metal, aluminium, steel, zinc, plastic, polyvinyl chloride (PVC), timber and wood-based, paint, timber, cladding, walls, durability, corrosion, rust, roof cladding, translucent sheets, wall cladding, profiled steel cladding
Cause
Galvanised coating has eroded to expose bare metal
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Profiled metal cladding is in contact with or has run-off from cedar or redwood, or timber treated with copper-based preservative treatment
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Galvanised mild steel cladding has run-off from translucent sheeting (PVC), glass, pre-painted roofing, glazed tiles, unpainted zinc/aluminium alloy-coated mild steel or aluminium
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Damage to the galvanised coating during fixing exposing steel
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Exposure to a corrosive environment such as a swimming pool, or in coastal, industrial or geothermal areas
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Inadequately primed end and/or side laps
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Cladding in ground contact
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- clear away ground in contact with the cladding; excavate adjacent soil to lower the ground level; slope ground away from the building
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Cause
Insufficient rain washing
Repair
- sand the corroded areas to remove rust; prime with a zinc-rich primer and a metal primer, repaint applying a minimum two coats of acrylic paint, or in accordance with manufacturer’s recommendations
- replace badly corroded sheets; ensure the new material is compatible with surrounding materials
Maintenance Charts
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Maintenance Schedule
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Stain Removal Guide
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