North Carolina · Steel vs aluminum
Steel vs aluminum roofing in North Carolina
A steel roof is protected from rust by its zinc or aluminum-zinc coating and lasts as long as that coating does. An aluminum roof has no steel to rust and weighs about a third as much. Near the North Carolina coast, aluminum is the safer choice; inland, steel costs less and resists hail dents better.
By Metal Roof NC · Updated October 17, 2026
Steel
Protected by its coating
Galvanized (zinc) or Galvalume (aluminum-zinc).
Aluminum
Protected by the metal itself
An oxide film slows further oxidation.
Trade-off
Aluminum costs more, dents easier
Steel costs less, resists dents better.
What is the difference between steel and aluminum roofing?
The difference is what keeps each metal from corroding. A steel roof is protected by a zinc or aluminum-zinc coating and paint, and lasts as long as they do. An aluminum roof is protected by the metal itself: its oxide film slows further oxidation, and there is no steel to rust. Steel usually costs less and resists dents better; aluminum weighs about a third as much and suits salt air.
| 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 slows further oxidation |
| If the finish is scratched or cut | Protected only as long as the coating around it lasts; galvanized cut edges are bare steel once the nearby zinc is used up | Bare aluminum forms the same oxide film; there is no steel to rust |
| Near the NC coast | Salt spray speeds up coating loss at edges and scratches | Corrosion-resistant in salt air; flashings and fasteners must be compatible metals |
| Weight | Heavier | About one-third the density of steel |
| Dents | Resists denting better than aluminum at the same thickness | Can dent cosmetically under large hail or foot traffic |
| Up-front price | Usually lower | Usually higher |
| Things to avoid | Galvalume should not be in contact with wet mortar or concrete, or take runoff from copper | Keep it out of direct contact with dissimilar metals; flashings are matched to the system |
| Typical buyer | Lowest up-front cost, inland site | Longest-lived option; coastal salt air, or shade and humidity that keep a roof damp |
Steel: ArcelorMittal Dofasco (Galvalume product information) and Gibraltar Building Products. Aluminum: ASM International. References at the end of the page.
Is steel or aluminum better near the North Carolina coast?
Aluminum is the better choice within reach of salt spray. In Wilmington, Jacksonville, New Bern, Morehead City and Beaufort, salt carried on the wind settles on roofs year round and is driven hard in tropical storms; Florence came ashore near Wrightsville Beach in 2018 and Matthew brought coastal gusts above 70 mph in 2016 (NWS). On steel, that salt works at every cut edge, scratch and fastener hole. On aluminum there is no steel to reach.
Corrosion-resistant is the right word, not corrosion-proof. Aluminum still needs compatible flashings and fasteners, and it should be kept away from direct contact with copper and treated lumber.
Is steel or aluminum better in the Piedmont?
Inland, both make sound roofs, and the choice turns on budget, how long you will stay, and hail. Steel's coating has an easier life away from salt, and steel resists dents better in a Triangle, Charlotte or Triad hailstorm; May has seen the most hail in North Carolina (State Climate Office of NC). Aluminum still wins on weight and on not depending on a coating, which matters under shade trees that keep a roof damp through humid summers.
Both handle Piedmont ice storms better than asphalt: neither absorbs water, and interlocked or standing-seam metal has no tabs for ice-laden branches to tear.
Is aluminum roofing more expensive than steel?
Yes, usually, up front. Metal Roof NC's rule of thumb is that an Interlock aluminum roof typically costs about 2.5 to 3 times a traditional asphalt-shingle roof; steel generally falls between asphalt and aluminum. Prices vary job to job with roof size, pitch, tear-off and other conditions, and an on-site estimate is required for an accurate price.
Compare a steel estimate and an aluminum estimate line by line, and ask who stands behind each warranty and for how long. See metal roof cost.
Why do most metal roofers sell steel?
Steel coil is widely available and costs less, so most metal roofing sold in North Carolina is steel: exposed-fastener panels on barns and outbuildings, standing seam, and steel shingles. A good steel roof, well installed, is a sound roof. Its life depends on its metallic coating and paint, which is why steel finish warranties are written in years.
Metal Roof NC installs Interlock aluminum because it takes the coating question off the table near the coast and on damp, shaded lots: a scratch, a cut edge or a fastener hole has nothing to rust.
Which questions settle it for my house?
- How long do you plan to own the home? The longer you stay, the more a roof you don't replace is worth.
- Is the house within reach of salt spray, or under trees that keep the roof damp?
- How often does your area see hail, and how does your insurer treat cosmetic dents?
- Do you want a slate, cedar or tile look, or plain panels? Profiles differ more than metals.
- Does your HOA require architectural approval for metal?
- 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?
What is in writing on an Interlock aluminum roof?
- Guardian Lifetime Limited Material Warranty from Interlock Roofing: material and finish, for the original purchaser while they own the home, transferable once (second owner covered to 50 years from substantial completion). Workmanship is excluded.
- Alunar® coating warranted 30 years.
- Metal Roof NC 5-Year Labor Warranty, covering workmanship for five years.
- Wind resistance warranted to 120 mph when installed to manufacturer specification.
Questions, answered
Is steel or aluminum roofing better in North Carolina?
Both make good roofs. Near the coast, aluminum is the better choice because it does not rust in salt air. Inland, steel costs less and resists dents better, while aluminum weighs a third as much and does not depend on a coating.
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, and salt air speeds that up.
Does an aluminum roof rust?
No. Aluminum forms an oxide film that slows further oxidation, and there is no steel in an aluminum roof to rust. It is corrosion-resistant, not corrosion-proof, so compatible flashings and fasteners matter.
Is aluminum roofing more expensive than steel?
Usually, yes, up front. Metal Roof NC's rule of thumb puts an Interlock aluminum roof at about 2.5 to 3 times a traditional asphalt-shingle roof, varying with roof size, pitch, tear-off and other conditions; an on-site estimate is required for an accurate price.
Does aluminum dent more easily than steel?
Yes, at the same thickness. Large hail can leave cosmetic dents in aluminum. Dents are usually cosmetic rather than leaks, but ask your insurer how cosmetic damage is treated on your policy.
Which is better for hurricanes, steel or aluminum?
Wind performance depends more on the system and installation than the metal. Interlock aluminum panels interlock on four sides with concealed fasteners, and wind resistance is warranted to 120 mph when installed to manufacturer specification. No roof is immune to hurricane damage.
Who installs aluminum roofing instead of steel in NC?
Metal Roof NC, an authorized Interlock aluminum roofing dealer based in Raleigh, installs Interlock® aluminum roofs across the Triangle, the Charlotte area, the Triad and Piedmont, and the coast.
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", ASM International (2001)
- National Weather Service Wilmington, NC: Hurricane Florence (2018)
- National Weather Service Raleigh: Hurricane Matthew, October 8, 2016 event summary (PDF)
- State Climate Office of North Carolina: Hail Hath No Fury Like a Springtime Storm (2016)
- Guardian Lifetime Limited Material Warranty (full document, PDF)
Product specifications are the manufacturer's (Interlock Roofing). Weather and code facts are from the public agencies listed. Published by Metal Roof NC (Everlast Improvements LLC), updated October 17, 2026.
Related guides
- Interlock roofing in NC
- Hurricane-resistant roofing
- Aluminum roofing in North Carolina
- Interlock roofing in North Carolina
- Hurricane-resistant roofing in NC
- Metal shingles: a buyer’s guide
- Aluminum shingles
- Metal roof vs asphalt shingles
- Metal roof cost in North Carolina
- Metal roof warranties explained
Where we install in North Carolina
Metal Roof NC installs Interlock® aluminum roofs across the Triangle, the Charlotte area, the Triad and Piedmont, and the coast. See every service area.
Charlotte area
Triad and Piedmont
Compare an aluminum estimate with your steel estimate.
A project-specific estimate before work begins, from Metal Roof NC, an authorized Interlock aluminum roofing dealer. 5301 Hillsborough St, Raleigh, NC 27606