← Critical Product/Equipment/Process: Metals, Mining & Materials (all topics)
GP/GC galvanised vs galvalume (Al-Zn) coating
What it is
Two coating systems for steel sheet. Galvanised plain and corrugated sheet carries a pure zinc coating that protects sacrificially; galvalume uses an aluminium-zinc alloy that resists corrosion far longer in most environments but protects cut edges less well
Both serve roofing, cladding and appliance markets, with galvalume commanding a premium
Impact on industries
- Galvalume's longer life supports premiumisation and better realisation than commodity GP/GC in the same end-use
- Substitution toward galvalume reduces zinc intensity per tonne, partially insulating the coater from zinc price spikes
- Buyer awareness is limited in the rural roofing market where price dominates, so premium adoption is slower than the technical case implies
- Coastal and industrial environments favour different coatings, so the choice is application-driven rather than a simple upgrade path