When deciding what material to purchase for your metal roof, you may have come across various options like steel, copper, aluminum, galvanized, and galvalume. Among them, the last two are the most popular. So what’s the difference, and how do you know which one is right for you?
Weighing the pros and cons of galvalume and galvanized roofing can certainly be confusing. And since installing a new roof can already be a costly and stressful process, we’re eager to offer our expertise. We’ve created a helpful guide to walk you through choosing the right roofing material for your needs.
Learn more about the two materials to decide which is best suited for your project.
What Is Galvalume?
Galvalume is a steel-based roof coating type that includes aluminum, zinc, and silicon. As one of the most popular roofing materials on the market today, it’s impressively durable. Aluminum makes up more than 50% of the coating, making it more resistant to corrosion.
Invented by Bethlehem Steel Construction Company in the early 1970s, galvalume coating is made by hot-dipping the metals onto steel coils to make them adhere to the material. The coating can remain with a plain mill finish, or be painted in a variety of colors.
Before galvalume, metals were only coated with zinc as a barrier against corrosive factors. The resulting product, called galvanized steel, is better protected from corrosion and natural elements like sunlight and water than bare metal.
What Is Galvalume Used For?
The main purpose of galvalume is to protect steel from oxidizing (rusting), which compromises the integrity of the material. It has many uses and purposes, but the most common application is for outdoor metal paneling and metal roofs. It might be installed on a wall, building trim, or as an accent, especially in climates subject to hurricanes, humidity, extreme heat, or high rainfall or snowfall.
Some of its standard applications include:
- Commercial: Office buildings, hospitals, schools, supermarkets, shopping malls, and parking complexes
- Residential: Condominiums, apartments, single-family dwellings, sheds, and detached outhouses
- Industrial: Manufacturing plants, warehouses, storage rental facilities, and fleet parking
- Agricultural: Storage facilities, barns, and enclosures for non-animal use
Apart from roofing and siding, galvalume is also used in other applications. Its corrosion resistance and high heat reflectivity make it ideal for:
- Appliance Components: Microwave oven frames, refrigerator drain pans, washing machine bases, and electric range ducts
- Vehicle Parts: Sub-floor, cab housings, and mufflers
Construction: Ductwork, piping, solar panels, and structural frames
Galvalume is not an ideal material for fastener installation or for environments in which it may be exposed to alkaline, which compromises the aluminum within the coating. It is also not well-suited for environments where it could get scratched or dented since damaged galvalume does not perform well.
Moreover, galvalume metal roofs should not be used in buildings that house animals since manure breaks down the galvalume coating over time.
Given the above, here are a few instances where you should not consider this type of metal roof:
Marine Environments or Coastal Areas
Galvalume’s zinc-aluminum coating cannot withstand prolonged exposure to significant volumes of salt, commonly found in the air of coastal areas. Saltwater is highly corrosive, which can quickly degrade galvalume roofing.
Avoid installing this metal roofing material on properties along the coastline, near large bays, surf breaks, and marshes. Aluminum is preferred to coated metal in these areas, as the metal is more resistant to saltwater-induced corrosion and rusting.
Livestock Housing or Enclosures
As mentioned, galvalume isn’t ideal for buildings used to house or enclose livestock. Its aluminum and zinc coating reacts with the ammonia from livestock manure. Animal waste breaks down into ammonia gas, creating a highly aggressive and corrosive environment that can damage metal roofing and walls.
Once the metal loses its protective coating, it will rust and corrode within a short time. If you choose to use this material for structures used for animal confinement, they must have adequate ventilation to reduce ammonia gas concentration and its corrosive effect on galvalume. Otherwise, it’s best to use galvanized or pre-galvanized materials or insulated metal panels.
Benefits of Galvalume
When used in the right circumstances, galvalume offers many unique benefits, especially in comparison to galvanized steel. Here are just a few of the reasons you may opt for galvalume.
1. Resistant to Corrosion
Galvalume is most valued because of its resistance to corrosion. Because aluminum is added to the coating, it is twice as resistant to corrosion as galvanized steel. The material is well-suited for environments with exposure to high humidity and extreme weather.
Because galvalume is lightweight, it has an impressive strength-to-weight ratio. The flexible coating won’t crack or flake off, even when the sheet metal is manipulated or bent.
3. Energy Efficient
Galvalume is highly reflective and resistant to extreme temperatures, meaning it minimizes absorption of heat and boosts energy efficiency when used as a roofing material. Using galvalume roofing panels will reduce both cooling and heating expenses throughout the year.
Many people choose galvalume because of its low price point in comparison to galvanized steel. It is a low-maintenance material that will last for at least 40 years, providing significant savings throughout its lifetime.
All metal roofing offers significant longevity, but galvalume stands out for its superiority in standing the test of time. While a galvanized steel roof may start aging within 10-15 years, galvalume roofing won’t start to wear out for at least 20-30 years.
Galvalume is extremely versatile and can be used in a variety of settings. It can be rolled or bent with ease or stamped to change its appearance. The panels can even be installed over asphalt shingles or over the top of a wood underlayment.
The Disadvantages of Galvalume
Contrary to popular belief, galvalume isn’t indestructible. There are several downsides to using this material for your roofing.
Oil canning refers to the visible waviness or distortion on the flat surface of a metal panel. It is innate in light-gauge, cold-formed metal products, particularly those with wide flat areas.
This issue is only cosmetic and won’t impact galvalume’s strength, durability, performance, or lifespan. Moreover, it can affect other metal construction materials, including stainless steel, galvanized metal, copper, zinc, and aluminum.
Oil canning doesn’t indicate the quality or structural issues with the roof, so it’s not considered a valid warranty claim as it won’t affect material performance. However, it can be unsightly, which can impact the overall appearance of the structure.
If you opt for unpainted galvalume, it’s important to know that its acrylic coating can scrape off easily. Once scuffed, the exposed portion of the metal panel ages and weathers faster due to the lack of a protective layer.
Since you cannot fix the scraped surface, you may have to replace the entire section. Scuffing can also occur after the material gets dented, so avoid surface damage by limiting foot traffic and minimizing pressure or weight on the panels. If you need to place a ladder against the roof, do so in a way that it won’t scratch the surface.
May Not Pair with Certain Materials
Although galvalume is highly durable, using it alongside other construction materials can speed up the degradation process. When installed directly on bricks, concrete, treated lumber, or other metals like iron and copper, this material may corrode in response to an electrolyte, like water. Plus, mortar and concrete are highly alkaline, making them corrosive to galvalume.
If left unchecked, rust and corrosion can cause the roofing structure to fail. When the design requires galvalume with the materials mentioned above, take precautions to minimize the risk of corrosion.
What Is the Difference Between Galvanized and Galvalume?
As you now know, galvanized and galvalume roofing materials have distinguishing characteristics and are not interchangeable. So what are the main things to note about galvalume vs galvanized steel? Here are some key points.
What Is Galvalume Made Of?
Galvanized steel is made completely of zinc, while galvalume includes aluminum, zinc, and a small amount of silicon. This provides superior durability and resistance to corrosion in comparison to galvanized coating.
The breakdown of galvalume’s alloy coating is as follows:
- 55% aluminum
- 43.4% zinc
- 1.6% silicon
The combination enhances aluminum’s positive and negative properties, offering better corrosion and heat resistance. However, it also loses some of its galvanic protection, making it more prone to scuffs and dents.
Which Is Thicker—Galvanized or Galvalume?
Galvalume and galvanized steel are both made through a hot-dipping technique and have a similar thickness, which is usually around 1 millimeter. This thickness may vary slightly from one material to the next, but if the galvalume and galvanized steel coating are of the same thickness, the galvalume coating will usually last longer than the galvanized coating.
Does Galvalume Last Longer than Galvanized?
As we’ve mentioned already, galvalume tends to last almost twice as long as galvanized steel before it shows any signs of wear. This is mainly due to the aluminum that is added to the coating to prevent oxidation.
When Should Galvalume Be Used?
Thanks to its corrosion-resistant properties, galvalume is ideal for humid and hot environments, commercial buildings, residential homes, storage units, and more. Galvanized metal roofing is better suited for dry climates, free of major air pollution or pooling water.
Although galvalume is considered more durable than galvanized steel, it’s important to refrain from using it for animal enclosures and properties near saltwater. Ammonia and salt are detrimental to the aluminum-zinc coating, leaving the metal underneath unprotected and prone to corrosion.
What Does Self-Healing Mean for Galvalume?
Most steel roofing materials end up having some “edge creep” near the edges where the panel was cut. Fortunately, galvalume is “self-healing,” meaning it eventually stops creeping and won’t spread rust all over the panel. But galvanized steel is not self-healing—the edge creep rusting will only worsen over time.
The combined self-healing and rust-resisting properties of zinc and aluminum ensure that the material remains structurally sound despite its exposed edges. Eliminate the risk of edge creep through hemming or touching up the bare spots with paint.
Which Has a Better Warranty?
Most galvalume roofing materials come with a warranty because they’re known for being durable and long-lasting. However, many galvanized materials do not have a warranty since they can be unpredictable and unreliable, especially once they begin to rust.
Is Galvalume More Expensive?
Because galvanized and galvalume steel are made in a similar fashion, they’re sold at a similar price. All steel roofing is more expensive than asphalt shingles, but the long-lasting nature of the product means it is usually more cost-effective overall.
As we outline in our metal roofing cost guide, other factors also affect project pricing. Underlayment, complexity, and scope are some considerations that can weigh on the total cost. If you want to know how galvalume compares to other roofing materials, request a quote from different roofers.
Which of the Two Looks Better?
Galvalume is generally considered to be more favorable in appearance when compared to galvanized steel. The differences between the two coatings are subtle, but galvalume offers a smoother, matte appearance, while galvanized coating is more rough and shiny.
Purchase Galvalume Today
Choosing the right type of steel coating can be overwhelming, but now that you know more about these types of roofs, you’re better equipped to handle the big task of installing a new one.
Does galvalume sound like the right choice for your next project? If so, contact 1st Coast Metal Roofing Supply to order your high-quality galvalume materials. We’re happy to answer any of your questions about galvalume metal roofs and help you decide if you’re still comparing galvalume vs. galvanized roofs. Get in touch today for a free quote.