Galvanized steel coil carries a pure zinc coating; Galvalume coil uses 55% aluminium, 43.4% zinc, and 1.6% silicon. Galvalume wins in rural and industrial atmospheres and at high temperatures, often lasting 1.5 to 2 times longer unpainted. Zinc wins in alkaline and coastal conditions and where cut-edge protection matters most, because zinc sacrifices itself further. Galvanized is easier to paint and weld; Galvalume needs careful pretreatment and must not contact concrete or wet wood. Choose by environment, not habit.
