Galvalume is steel sheet coated in an aluminum and zinc alloy, roughly 55 percent aluminum. The aluminum gives broad corrosion resistance and the zinc protects cut edges and scratches. It is the usual substrate under painted steel roofing panels.
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Both are coated steel; the coating chemistry differs and so does where each performs.
| Galvalume | Galvanized | |
|---|---|---|
| Coating | Aluminum-zinc alloy | Zinc |
| Broad surface corrosion | Better | Good |
| Protection at cut edges | Good | Better |
| Common use | Substrate under painted panels | Trim, some bare applications |
what sits inside a roofing quote covers where substrate choice sits in a quote.
Yes, and acrylic coated bare Galvalume is a legitimate finish with a distinctive silver grey look that dulls over time. It costs less than a painted panel.
Two cautions. Bare Galvalume should not be used where it will be in contact with wet concrete, mortar or treated lumber, and it is not recommended in animal confinement environments. how metal roofing is installed covers the wider system.
For broad surface corrosion on a roof, generally yes. Galvanized has the edge at cut edges and scratches, which is why coating choice depends on the application.
Commonly yes. The painted finish sits on a Galvalume substrate, so you get both the coating and the paint system.
No. It weathers to a duller grey over time, which many people choose deliberately.
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