Many people experience confusion about the differences between Galvanized steel and Galvalume for metal roofing.
- Are Galvanized steel and Galvalume the same thing?
- What are the differences?
- And which type is the better choice to install on your roof?
Despite the similarity in name, Galvalume and Galvanized roofing are two different products that share similarities while still having many significant differences. You can find answers for these questions after reading this article.
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Galvanized More Popular Than Galvalume?
Both types of metal are common choices for metal roofing due to their durability, longevity, and aesthetics. But since these are different products, multiple factors determine which type is best for specific situations.
These 2 metals have a similar weight of 100 to 150 pounds a square (100 square feet), and both options consist of around 35% recycled steel.
Although galvanized metal is the more popular choice, this reputation is almost two hundred years of use for residential and commercial roofing. In comparison, Galvalume first hit the market in 1972, meaning it's only been around nearly sixty years.
Many people are still unfamiliar with Galvalumium as a roofing option. Many people mistakenly refer to metal roofs as tin roofs while referring to galvanized steel due to the similarity in appearance.
What is Galvalume Roof?
Galvalume has a lifespan of 50 to 60 years or more. During production, a carbon steel base sheet is continuously hot-dipped in alloys of zinc and aluminum to create a coating of 55% aluminum, 43.4% zinc, and a 1.6% content of silicone.
Both zinc and aluminum protect the steel from corrosion - zinc by creating a resistant barrier against moisture while aluminum also reflects heat. The added silicone helps the coating adhere to the surface, so there's no damage during bending, rolling, or stamping.
Some people may refer to Galvalume as AZ-55 - unpainted or AZ-50 - painted. This code is the weight of the coating. Due to the combination of three durable metals, Galvalume is a superior product to use for regions with high rain, snowfall, hurricanes, high temperatures, and heavy salt spray.
However, this product will not work on buildings containing concrete, animal housing (barns or stables) - manure releases ammonia gas which breaks down the coating, or along coastlines, bays, marshes, or breaking surfs.
Galvalume has self-healing properties that stop the normal red rusting that occurs along the cut edges. This ability keeps the rust from spreading, causing damage to your roof.
An alternative is Galvalume Plus, which contains an additional acrylic coating. The topcoat makes this metal easier to roll-form and installs on-site.
- Stands up against corrosion from heavy-salt and severe marine locations
- More resistant to corrosion than G-90 galvanized steel
- 25.5-year warranty on substrate (perforation warranty)
- Affordable cost - $5-$15/sq ft
- Self heals
- Bare metal or pre-painted
- It can't be used in combination with mortar (bricks) or concrete
- A potential risk of oil canning (visible waviness of metal that doesn't affect performance)
- Corrosion can occur when Galvanized metals come in contact with treated lumber, iron, or copper
- You cannot use it with exposed fasteners
- The paint doesn't stick as well, resulting in more flawed aesthetics
What is Galvanized Steel Roof?
Galvanized metal has an inner core of steel that's topped with a protective Zinc layer to prevent corrosion. To create Galvanized steel, a sheet of steel (or iron) substrate gets hot-dipped in zinc. This type of metal roofing has an average lifespan of 50 years.
You may also hear this type of metal referred to as G-90, which refers to the weight of the coating. It can be challenging to find many options for Galvanized metal because most companies have transitioned to Galvalumium due to its superior performance.
The manufacturing process for Galvanized steel creates a chemical bond that makes the metal resistant to scratches, nicks, and corrosion and allows for self-healing to correct minor scratches. But if corrosion starts, it spreads quickly, which will cause the galvanization layer to shed, leaving the inner steel layer unprotected.
- A medium price point of $5-$13 a square foot
- Suitable for most locations
- Bare metal or pre-coated with Hylar 5000 or Kynar 500 paints
- Holds paint better for less frequent repainting
- Red rust can occur and spread if there's damage to the steel core
- Doesn't self heal
- Potential for oil canning
- Rarely has substrate warranties
Galvalume vs Galvanized
Both types of metal are common for roofing in residential and commercial buildings. But they have significant differences that set them apart.
# of Materials
The most significant difference is construction.
Galvalume is made using three crucial metal components - zinc, aluminum, and low amounts of silicon - while Galvanized steel is zinc.
Both galvanized steel and Galvalume are close to 1 millimeter thick due to the hot-dip process. But the final thickness will vary by material, manufacturer, and production process. At the same thickness, Galvalume coatings will last longer than galvanized.
Both products have an extended lifespan of decades, with Galvanized steel lasting 50 years before showing signs of corrosion, while Galvalume can last more than 60 years before displaying signs of aging.
Galvalume is ideal for use in locations with hot, humid climates, whereas Galvanized metal works better in dry environments with little air pollution. Pooling water is also a danger to galvanized.
However, you can't use Galvalume for buildings that contain animals, like horses, cows, or pigs. You can use this material for chicken coops when done correctly. For outdoor structures for animal habitats, consider galvanized metal instead.
The final factor to consider when debating between Galvalume vs. Galvanized metal is the look. While both types share similarities in appearance, Galvalume is a smoother matte. Galvanized metal has a shiny, rougher surface and style.
Which is Your Best Choice?
When trying to decide between Galvalume vs. Galvanized steel, consider these factors to help you make the right choice.
Where you live will play a significant factor in which type of metal roofing you select. Consider the typical weather in your area.
If you experience high humidity levels, significant levels of rain or snowfall, extreme heat, or hurricanes, you will do better with Galvalume, which is more durable and corrosion-resistant.
- House Materials
If your home has concrete, masonry, treated wood, or other alkaline materials, you will do better with Galvanized steel. The aluminum in Galvalume will corrode with exposure to alkalines, which can cause the metal to degrade and lose its strength.
You'll also want to consider your budget. Galvalumium costs $5-$15 per square foot, while Galvanized metal costs $5-$13 a square foot. However, be aware that the price of Galvanized steel does fluctuate. You may be able to catch a deal and get it cheap, or you may end up paying more than you would for a Galvalumium roof.
Q: Is Galvalume shiny?
A: Many people who choose a metal roof prefer the shiny, natural metal look. Galvalume has a matte finish, so it's more of a gunmetal gray with less sheen. If you want the shiny look of raw metal, you will get better results from Galvanized steel.
Q: Can I paint Galvalume?
A: Galvalume requires special prepping before it will adequately hold paint. You have to use an etching primer on Galvalume and then apply the paint using specialized brushes to keep the color from drying with flaws or flaking.
Q: Is Galvalume rated for Energy Star?
A: Galvalume is the only type of metal roofing that qualifies as Energy Star, a program established by the US Environmental Protection Agency (EPA) and the Department of Energy (DOE). Galvanized metal is not Energy Star qualified.