One of these metals can last over 50 years outdoors… can you guess which?
If you’re building a backyard shed, choosing siding for a coastal home, or even picking the right patio furniture, you’ve likely faced this head-scratcher: Does aluminum really last longer than galvanized steel?
The internet is full of conflicting advice. Some say aluminum is king because it never rusts. Others swear by galvanized steel for its toughness and durability.
We get it if you want the truth without needing an engineering degree.
In this article, we’re breaking down the battle between these two popular metals in a way that’s simple, visual, and based on real-world use, not just lab tests or manufacturer claims.
Meet the Contenders: Aluminum vs. Galvanized Steel
Before we dive into performance and longevity, it helps to know what these metals are and how they differ, especially in a side-by-side comparison.
What They Are
- Aluminum : A lightweight metal that resists corrosion naturally by forming a protective oxide layer. Common in marine, roofing, and outdoor applications.
- Galvanized Steel: Steel coated with zinc (via hot-dip or other methods) to prevent rust. Durable and strong, but corrosion protection depends on an intact zinc layer.
Quick Comparison of Key Properties
| Property | Aluminum | Galvanized Steel |
|---|---|---|
| Weight | Light about one‑third the density of steel (≈2.7 vs. ≈7.85 g/cm³) | Dense and heavy adds strength but increases handling costs |
| Corrosion Resistance | Excellent naturally forms an oxide layer that renews itself | Good when coating remains intact, but zinc layer wears or scratches over time |
| Strength & Stiffness | Lower tensile and yield strength, but high strength‑to‑weight ratio (e.g. 6061‑T6 alloy) | Higher tensile/yield strength and much stiffer (elastic modulus ~3× aluminum) |
| Malleability/Formability | Highly malleable, easy to bend or shape complex forms | Moderately malleable but more difficult to shape without heating or special tools |
| Cost (Initial) | $1.50–3.00 per lb; higher upfront cost due to energy‑intensive processing | $0.50–1.50 per lb; cheaper initially and widely available |
| Lifecycle Cost | Often lower over decades ,thanks to less maintenance and longer corrosion resistance | Lower upfront cost, but may require repainting or zinc re-coating over time |
Battle of the Elements: How Each Metal Handles Time
Curious which metal holds up best over rain, snow, salt spray, and blazing sun? Let’s compare their real-world performance:
Lifespan by Environment
| Environment | Aluminum Lifespan | Galvanized Steel (Hot‑Dip) |
|---|---|---|
| Mild, inland climate | 40–60 years, minimal rust risk | Up to 70 years before maintenance |
| Coastal / Salt‑air zones | 40–60 years, resists salt well | Only 10–20 years in corrosive settings |
| Industrial / polluted air | 40–60 years, oxide layer helps | 20–40 years depending on pollutants |
| High sun / UV | Stable oxide protects surface | Zinc patina slows degradation |
| Snow / moisture-heavy | 40+ years; corrosion low unless scratched | 40–70 years generally in roofs |
Both metals hold strong: aluminum roofs average 50+ years, especially in coastal zones, while galvanized steel roofs typically last 40–70 years with good installation.
Key Takeaways
- In dry, mild climates, both metals perform similarly.
- In coastal or polluted areas, aluminum typically lasts longer with less upkeep.
- In high‑impact or heavy‑load applications, steel’s strength often offers longer structural service.
5 Surprising Factors That Affect Metal Lifespan
It’s not just rust or lack of it that decides how long aluminum or galvanized steel lasts. These five factors matter more than you might think.
Coating Thickness & Design
Thicker zinc on galvanized steel shields better. Thin coatings wear out faster. The coating may protect even damaged areas by acting as a “sacrificial anode” around scratches, thanks to galvanic action.
Better design fewer crevices, smooth joins reduces localized corrosion like pitting or crevice corrosion.
Environmental Chemistry
Salt (chloride ions) and industrial pollution (sulfates, SO₂) drive corrosion faster. In coastal or polluted zones, galvanized steel may last just 5–10 years.
Aluminum resists salt better, but strong alkalis or acidic rain can damage its oxide layer.
Moisture & Wetness Duration
Stagnant water or high humidity fosters corrosion pits or crevices. Steel under constant wet cycles or in sheltered damp spots corrodes faster.
Aluminum’s oxide layer handles regular moisture well but trapped water in joints or under buildup can still cause corrosion over time.
Fasteners & Contact with Other Metals
Using dissimilar metals or fasteners (e.g., steel screws on aluminum) can create galvanic corrosion. That often attacks the less noble metal, typically aluminum.
Even zinc-rich coatings on steel may be compromised if contacted by incompatible materials.
Maintenance & Protective Finishes
Powder coating, paint, or chromate layers extend both metals’ lives. But coatings break or peel. Repaints or touch-ups help steel more often since zinc erodes.
Aluminum doesn’t require much upkeep if undamaged and its protective oxide fixes itself but scratches, dents, or chemical exposure do create risks.
Mythbusters & Surprises:
- Heavier doesn’t always mean stronger long‑term. Steel may feel solid, but if the zinc wears away fast in salt air, it fails earlier than aluminum.
- Aluminum can dent but dents don’t mean rotting. Steel resists impact better, but once corrosion starts, it spreads faster.
- Thicker metal doesn’t guarantee longer life. Poor design that traps water or creates crevices collapses lifespan, regardless of how thick the material is.
The Longevity Leaderboard: Use‑Case by Use‑Case
Curious which metal wins in specific scenarios? Let’s put aluminum and galvanized steel head‑to‑head across common projects:
Roofing & Siding
- Aluminum: Lasts over 50 years with minimal corrosion. Light and ideal for coastal homes.
- Galvanized Steel: Typically lasts 40–70 years, but zinc wears faster near salt air. Slightly heavier and more impact-resistant.
Outdoor Furniture
- Aluminum: Rustproof and low‑maintenance. Often lasts 20+ years, moves easily, resists weather.
- Galvanized Steel: Stronger initially with a zinc coating. May last 15–20+ years with touch‑ups. More prone to rust if coating fails.
Marine or Coastal Gear
- Aluminum resists salt air exceptionally well. Ideal for docks, boats, or fixtures near the ocean.
- Galvanized Steel corrodes rapidly in salt zones,and the zinc layer may last just a decade.
Industrial & Infrastructure
- Aluminum siding: Typically 30–40 years lifespan. Easy to install, dents easier.
- Galvanized steel siding: Can last 40–70 years. Offers better impact resistance, but needs coating upkeep.
Quick Summary Table
| Project Type | Aluminum Severity | Galvanized Steel Edge |
|---|---|---|
| Roofing & Siding | Long‑lasting & corrosion‑resistant | More impact‑resistant, long inland life |
| Outdoor Furniture | Lightweight, rust‑proof | Heavier, more rugged with upkeep |
| Marine / Coastal Gear | Excellent in salt air | Zinc fails quickly in salty conditions |
| Industrial / Infrastructure | Less weight, less load capacity | High strength, proven long life |
| Siding & Fencing | Easy install, dent‑prone | Tougher panels, longer lifespan inland |
Cost vs. Value: What Lasts Longer and Saves You More?
When choosing between aluminum and galvanized steel in Canada, it’s not just the sticker price that matters, it’s how far that dollar goes over decades.
What You Pay Upfront
- Aluminum: Roughly $1.00–$1.50 USD per pound, or about $1.40–2.10.
- Galvanized Steel: Around $0.30–$0.60 USD per pound, or $0.40–0.85 per pound.
This makes aluminum roughly 2–3× more expensive by weight.
What You Save Over Time
- In coastal or corrosive zones (like Ontario, British Columbia, and maritime provinces), aluminum’s natural oxide layer resists rust without repainting often outperforming steel in total cost of ownership.
- In urban or inland Canada, aluminum and hot-dip galvanized steel reach near parity in 50-year lifecycle costs. In maritime climates, aluminum often becomes more economical after just ~21 years due to its superior corrosion resistance.
Installation & Use
- Aluminum’s lighter weight reduces shipping and handling costs.
- In projects like bridges or large structures, aluminum may cut installation time and equipment needs, and pay back its cost premium faster.
- Fabricators in Canada often find aluminum easier to machine and shape especially useful for custom profiles or lighter construction.
Maintenance & End of Life
Conclusion
Choosing between aluminum and galvanized steel comes down to your project type, environment, and long-term costs.
- Aluminum shines in coastal or humid zones lasting longer with almost zero rust or maintenance.
- Galvanized Steel stays strong inland or in industrial settings and still offers excellent durability, so long as you maintain zinc coatings.
What to Do Next
If you want to explore galvanized steel options built for longevity and strength in Canadian conditions, check out our prefab solutions .
We specialize in Galvalume Plus™ steel structures that meet CSA-A660 standards and offer unmatched strength from garages to commercial building kits.
Our experience includes:
- Fast installation with prefab kits
- Durable structures designed for Canadian climates
- Reliable support and engineering-backed solutions
Curious about pricing, design options, or special installations? Get in touch we’re here to help you build smart and last long galvanized steel you can trust.
