Aluminum vs. Galvalume vs. Steel Roofing
Quick answer
The key difference is corrosion. Aluminum contains no iron and cannot rust. Galvalume is steel with a zinc-aluminum coating that resists rust well inland but is sacrificial and can fail at cut edges. Bare galvanized steel is the most rust-prone. For coastal and lifetime use, aluminum wins; Galvalume is a solid inland value; plain steel is budget-tier.
Three metals, three corrosion stories
All three make metal roofs, but they age very differently because of how they fight corrosion. Aluminum does not fight it at all — with no iron, it cannot rust, and its oxide layer re-seals if scratched. Galvalume is steel protected by a zinc-aluminum alloy coating that performs well but is slowly consumed and thinnest at cut edges. Galvanized steel uses a pure-zinc coating that wears faster. The more sacrificial coating a roof depends on, the more its lifespan hinges on that coating surviving.
Head-to-head comparison
Corrosion resistance, coastal suitability, weight, and cost separate the three.
| Factor | Aluminum | Galvalume steel | Galvanized steel |
|---|---|---|---|
| Rust resistance | Cannot rust | High inland; sacrificial | Lowest; rusts soonest |
| Coastal / salt air | Excellent | Often limited by warranty | Not recommended |
| Weight | Lightest | Heavier | Heavier |
| Upfront cost | Premium | Mid | Lowest |
| Best for | Coastal & lifetime | Inland value | Budget / utility |
How to choose
If you live near salt water or in a wet, humid climate — or you simply want a lifetime roof you never revisit — aluminum is the clear pick, which is why Interlock builds exclusively in aluminum. If you are inland with a moderate budget and want strong value, Galvalume is a sound choice. Plain galvanized steel makes sense mainly for outbuildings and utility structures where lowest upfront cost outweighs long-term corrosion concerns.
Frequently Asked Questions
Is aluminum or Galvalume better for roofing?
Aluminum is better for coastal, wet, and lifetime residential roofs because it cannot rust. Galvalume performs well inland and costs less, but its zinc-aluminum coating is sacrificial and many warranties limit its use near salt water.
Does Galvalume rust?
Eventually it can. Galvalume's zinc-aluminum coating resists rust well inland but is consumed over time and is thinnest at cut edges, where rust can begin. Aluminum avoids this because it has no iron to corrode.
What is the difference between galvanized and Galvalume?
Both are coated steel. Galvanized uses a pure-zinc coating; Galvalume uses a zinc-aluminum alloy that lasts longer and resists corrosion better. Neither matches solid aluminum, which cannot rust at all.
Which lasts longest?
Aluminum, generally — it does not rely on a sacrificial coating and cannot rust, so it routinely lasts 50+ years. Galvalume outlasts galvanized steel, but both depend on a coating that is eventually consumed.
Sources
- The Aluminum Association — Corrosion behavior — Aluminum corrosion resistance
- HomeGuide — Metal Roof Cost — Material cost context
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Last reviewed 2026-07-11 · Reviewed by Scott Plumptree, Director of Marketing