When it comes to metal roofing, the difference between galvalume and galvanized steel can make or break the long-term value of your project. Industry studies show that galvalume roofs can last 40–50+ years under normal conditions, while galvanized steel typically lasts 20–50 years, depending on climate and exposure. In real-world performance, galvalume consistently provides 2–4 times better corrosion resistance than galvanized steel.
This guide breaks down the composition, performance, cost, and best applications of each roofing material—so you can choose with confidence.
Galvalume vs Galvanized: What Are They?
Both coatings are designed to protect steel from rust, but their makeup—and performance—are very different.
Galvalume: Aluminum-Zinc-Silicon Alloy
- Composition: 55% aluminum, 43.5% zinc, 1.5% silicon
- Process: Hot-dipped coating, introduced in the 1970s by Bethlehem Steel
- Coating Grades: AZ50 (0.50 oz/ft², common for painted panels) and AZ55 (0.55 oz/ft², for unpainted use)
- Appearance: Bright silver, smooth, often non-spangled
The aluminum provides superior corrosion resistance, while the zinc offers sacrificial protection, and the silicon improves adhesion.
Galvanized Steel: Pure Zinc Coating
- Composition: 100% zinc coating over steel
- History: In use since the 1800s
- Coating Grades: G40, G60, G90 (the number refers to ounces of zinc per ft²; G90 offers the best protection)
- Appearance: Dull gray with a distinct spangled finish
The zinc barrier delays rust, but once it wears down, corrosion spreads quickly.
Visual and Surface Differences
- Galvalume: Uniform, smooth silver finish; often used unpainted for a sleek modern look.
- Galvanized: Distinctive mottled or “spangled” pattern; weathers to matte gray over time.
Corrosion Resistance and Longevity
The biggest performance gap between these two materials lies in how they resist rust.
- Galvalume: Creates a stable aluminum oxide layer that self-heals after scratches or cut edges. Rusting may occur at edges, but it does not spread.
- Galvanized: Once the zinc coating wears through, red rust spreads across the exposed steel.
Lab Testing: In salt-spray tests (ASTM B117), galvanized steel often shows red rust within 200–600 hours. Galvalume endures many times longer, making it a more reliable long-term option.
Expected Service Life:
- Galvalume: 40–50+ years
- Galvanized: 20–50 years, depending on thickness and exposure
Performance in Different Environments
Coastal & Humid Areas
- Galvalume: Outperforms galvanized in humid and coastal inland zones, lasting 10–25 years longer.
- Extreme Coastal (breaking surf): Neither is ideal—aluminum roofing performs best.
Agricultural Use
- Galvanized: Preferred for livestock buildings, as the high zinc content resists ammonia corrosion from animal waste.
- Galvalume: Not recommended for these environments.
Thermal Performance
- Galvalume: Reflects 5–10% more heat than galvanized, reducing thermal expansion and extending service life.
- Galvanized: More prone to micro-cracking under repeated heating and cooling cycles.
Impact Resistance
- Galvanized: Slightly harder surface, providing better dent resistance in hail-prone areas.
- Galvalume: Trades some dent resistance for better long-term corrosion control.
Cost and Warranty Coverage
Cost
Market prices fluctuate, but on average:
- Galvalume panels: $0.75–$1.15 per sq ft (26-gauge)
- Galvanized panels: $0.80–$1.30 per sq ft
Note: Galvalume is often marketed as 5–15% more expensive, but pricing shifts with supply and regional demand. Always confirm local quotes.
Warranty
- Galvalume: Backed by manufacturer substrate warranties up to 25 years or more, often paired with paint warranties.
- Galvanized: Typically no substrate warranty, especially at thinner grades like G40 or G60.
Best Applications
| Factor | Galvalume | Galvanized Steel |
|---|---|---|
| Composition | Aluminum-Zinc-Silicon | Pure Zinc |
| Lifespan | 40–50+ years | 20–50 years |
| Corrosion Resistance | 2–4× better | Lower |
| Heat Reflection | Higher (cooler roof) | Lower |
| Impact Resistance | Slightly lower | Slightly higher |
| Warranty | 20–25+ years typical | Usually none |
| Best Use | Residential & commercial roofs, humid or coastal inland | Agricultural, livestock buildings, hail-prone areas |
Conclusion
If you’re choosing between galvalume vs galvanized steel roofing in 2025, here’s the bottom line:
- Choose Galvalume for residential and commercial projects, especially in Florida’s humid, coastal, and high-UV environments. It lasts longer, reflects more heat, and comes with real warranty protection.
- Choose Galvanized if you’re working on barns, livestock facilities, or projects where dent resistance is more important than long-term corrosion performance.
While galvalume often costs slightly more upfront, its longer lifespan and warranty coverage usually make it the better long-term value.
FAQs
Q1. Which lasts longer: Galvalume or galvanized steel?
Galvalume typically lasts 40–50+ years, compared to galvanized steel’s 20–50 years, with far superior corrosion resistance.
Q2. What’s the main difference between the two?
Galvalume uses an aluminum-zinc-silicon alloy, while galvanized steel is coated only with zinc. This makes galvalume more corrosion-resistant.
Q3. Is Galvalume more expensive?
Slightly—on average 5–15% more, though regional market prices vary.
Q4. Does Galvalume rust?
Yes, but only at edges or scratches—and the rust stops spreading thanks to its self-healing aluminum layer.
Q5. When is galvanized steel better?
In agricultural settings (livestock barns) and sometimes in hail-prone areas, galvanized steel can be the better fit.