Idaho · Steel vs aluminum

Steel vs aluminum roofing in Idaho

Steel roofing costs less up front, resists dents better and depends on its zinc or aluminum-zinc coating to keep from rusting. Aluminum has no steel to rust and is about a third the weight. For a house you'll keep, aluminum is the longer-lived choice; for hail, compare impact ratings profile by profile.

Reviewed by Scott Plumptree, Director of Marketing, The Interlock Group · Updated October 8, 2026

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Corrosion

Steel relies on its coating

Aluminum's own oxide film protects it.

Weight

Aluminum ≈ ⅓ the density

ASM International.

Price

Steel usually lower

Compare written quotes line by line.

Side by side

Steel roofing compared with aluminum roofing
	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	Thicker steel resists denting better than thin aluminum	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, and should not take run-off from copper	Keep it out of direct contact with dissimilar metals; flashings are matched to the system
Typical buyer	Lowest up-front cost; outbuildings and shops	The longest-lived option for 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.

Why most metal roofers sell steel

Steel coil is widely available and costs less, so most metal roofing sold in Idaho, as everywhere, is steel: exposed-fastener panels on shops and barns, standing seam, 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 cut edge or a fastener hole has nothing to rust.

What Idaho weather changes in the choice

Hail

Steel's stiffness is its real advantage against dents. On the aluminum side, Interlock's Slate, Cedar Shingle, Shake and Mediterranean Tile profiles carry a UL 2218 Class 4 impact rating, verified by Intertek for Delta Building Products. Compare impact ratings profile by profile, not metal by metal.

Snow and freeze–thaw

Neither metal absorbs water. Both shed snow, so either roof needs snow guards where a slide would land on people, decks or cars. Snowmelt sitting at a scratched edge is where the coating on steel matters.

Wildfire

Neither metal burns. The fire rating belongs to the assembly: ask whether the roof is rated Class A with its underlayment and deck. An Interlock roof is Class A Fire Rated Available, as a complete assembly.

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.
Do you want a slate, cedar or tile look, or plain panels? Profiles differ more than metals.
What is the impact rating of the exact profile, and who tested it?
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 Idaho?

Both make good roofs. Steel costs less up front, resists denting better for the same thickness, and depends on its zinc or aluminum-zinc coating to keep from rusting. Aluminum doesn't rust and is about a third the weight. For a house you'll keep, aluminum is the longer-lived choice; compare impact ratings profile by profile.

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 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.

Is aluminum roofing more expensive than steel?

Usually, yes, up front. You get a written price for an Interlock® aluminum roof after your roof consultation, which is free, so you can compare it with a steel quote line by line.

Is steel roofing stronger than aluminum?

Steel is stronger and stiffer for the same thickness, which is why it resists denting better. Aluminum is lighter. On a roof deck, both carry snow load through the structure underneath; strength of the panel matters most for dents.

Who installs aluminum roofing instead of steel in Idaho?

Interlock Metal Roofing (PNW) Inc. installs the Interlock® aluminum roofing system in Idaho from our office in Boise. Call (208) 842-4762.

Sources

Product specifications are the manufacturer's (Interlock Roofing). Reviewed by Scott Plumptree, October 8, 2026.

Related guides

Compare a written aluminum price.

A written price after your roof consultation, at your home or on Zoom. Interlock Metal Roofing (PNW) Inc. · 3295 W Elder St, Suite 209, Boise, ID 83705

Get a free quote (208) 842-4762