Alberta · Steel vs aluminum
Steel vs aluminum roofing
A steel roof is protected from rust by its zinc or aluminum-zinc coating and paint, and lasts as long as they do. An aluminum roof has no steel to rust: its oxide film protects it, so a hail dent stays cosmetic, and it weighs about a third as much. Steel usually costs less up front and resists denting better; aluminum is the longer-lived choice.
Reviewed by Scott Plumptree, Director of Marketing, The Interlock Group · Updated October 8, 2026
Steel
Protected by its coating
Galvanized (zinc) or Galvalume (aluminum-zinc).
Aluminum
Protected by the metal itself
An oxide film blocks further oxidation.
Weight
Aluminum ≈ one-third of steel
By density, ASM International.
Side by side
| Steel roofing | Aluminum roofing | |
|---|---|---|
| What keeps it from corroding | A metallic coating, zinc (galvanized) or aluminum-zinc (Galvalume), under the paint | The aluminum itself: its oxide film blocks further oxidation |
| If the finish is scratched or cut | The steel is protected only as long as the coating around it lasts; galvanized cut edges are bare steel once the zinc nearby is used up | Bare aluminum forms the same oxide film; there is no steel to rust |
| Weight | Heavier | About one-third the density of steel |
| Dents and hail | Thicker steel resists denting better than thin aluminum; ask for the impact rating of the exact product | Can dent under large hail or foot traffic; dents are cosmetic and usually excluded from warranties |
| Up-front price | Usually lower | Usually higher |
| Things to avoid | Galvalume corrodes quickly in contact with wet mortar or concrete | Keep it out of direct contact with dissimilar metals; flashings are matched to the system |
| Typical buyer | Lowest up-front cost | Longest-lived option; a house you plan to keep |
Steel: ArcelorMittal Dofasco (Galvalume product information) and Gibraltar Building Products. Aluminum: ASM International. References at the end of the page.
Aluminum roofs in Alberta, after the winters and the storms
Recent Interlock® roofs installed in Alberta by our own company. Tap a roof to see all of its photos.
Hail changes the question in Alberta
Hail is where the two metals differ most in practice. Thicker steel resists denting better than thin aluminum. But a dent in steel that cracks the paint and coating opens the steel to rust over time, while a dent in aluminum is cosmetic: there is no steel underneath to corrode.
Interlock's Slate, Cedar Shingle, Shake and Mediterranean Tile aluminum panels carry a UL 2218 Class 4 impact rating, listed by Intertek under Delta Building Products.
Whatever metal you choose, ask which exact product carries which impact rating, who lists it, and what the warranty says about hail. The Guardian Lifetime Limited Material Warranty on an Interlock roof excludes hail larger than 38 mm (1.5 in), and hail damage is a matter for your home insurance.
Why many metal roofers sell steel
Steel coil is widely available and costs less, which is why many metal roofers sell steel: painted steel panels, steel shingles and stone-coated steel. A good steel roof, well installed, is a sound roof. Its life depends on its metallic coating and paint, which is why steel warranties are written in years.
We install aluminum because it takes the coating question off the table. An Interlock® panel has no steel in it, so a scratch, a dent, a cut edge or a fastener hole has nothing to rust.
Questions that settle it for your house
- How long do you plan to own the home? The longer you stay, the more a roof you never replace is worth.
- How often has your neighbourhood had hail? Ask your neighbours and your insurer.
- Do you want a slate, cedar or tile look, or plain panels? Profiles differ more than metals.
- Who is the warrantor, the manufacturer or the contractor, and what does the material warranty cover after year ten?
- Are the fasteners concealed or screwed through the face?
Questions, answered
Is steel or aluminum better for a roof in Alberta?
Both make good roofs. Steel costs less up front and depends on its zinc or aluminum-zinc coating to keep from rusting. Aluminum doesn't rust, so a hail dent or a scratch stays cosmetic, and it is about a third the weight. For a house you'll keep, aluminum is the longer-lived choice.
Does a steel roof rust?
Steel itself rusts; a steel roof is protected by its metallic coating and paint. Where the coating is cut, scratched, cracked by a dent or used up, as at galvanized cut edges over time, rust can start.
Does an aluminum roof rust?
No. Aluminum forms an oxide film that blocks further oxidation, and there is no steel in an aluminum roof to rust.
Which handles hail better, steel or aluminum?
Thicker steel dents less; aluminum dents more easily but has no steel to rust where it dents. Compare impact ratings product by product. Interlock's Slate, Cedar Shingle, Shake and Mediterranean Tile aluminum panels carry a UL 2218 Class 4 impact rating, listed by Intertek under Delta Building Products.
Is aluminum roofing more expensive than steel?
Usually, yes, up front. Our metal roof cost page shows real ranges from our recent Alberta contracts, and we give a fixed price in writing after one free visit, so you can compare it with a steel quote line by line.
Who installs aluminum roofing instead of steel in Calgary and Edmonton?
Interlock Metal Roofing (Alberta) Ltd. installs the Interlock® aluminum roofing system from its office in Calgary, which serves both Calgary and Edmonton, with 3,542 Alberta roofs completed since 1999. Call (587) 317-6517.
Sources
- ArcelorMittal Dofasco: Galvalume™ steel sheet, product information
- Gibraltar Building Products: why are the edges of my painted galvanized roof rusting?
- J.R. Davis, "Aluminum and Aluminum Alloys", Alloying: Understanding the Basics, ASM International (2001)
- Interlock Roofing: aluminum shingles, technical specifications
- Guardian Lifetime Limited Material Warranty (full terms)
Product specifications are the manufacturer's (Interlock Roofing). Install counts are from our own job book. Reviewed by Scott Plumptree, October 8, 2026.
Compare an aluminum quote with your steel quote.
A fixed price in writing after one visit, at your home or on Zoom. Interlock Metal Roofing (Alberta) Ltd. · 210, 3750 46 Ave SE, Calgary, AB T2B 0L1
