Galvalume® vs. Galvanized Metal Roofing - Sheffield Metals

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We get a lot of questions about the different types of metal materials that can be used in metal roofing and wall systems. There is one question that comes up more often than others:

What is the difference between Galvalume® and galvanized metal?

These two metals, which are technically coatings applied to a steel core, aren’t all that different from one another by definition. However, the benefits and drawbacks of Galvalume and galvanized metal significantly differ, including how long each one lasts, the expectations of how each one will perform, and more.

While our main product focus at Sheffield Metals is painted or bare 24-gauge Galvalume coils and sheets used in the standing seam metal roof and wall industry, we sell galvanized metal products as well. In essence, we believe it’s important that you know the different attributes of these two materials so you can make the best choice for your project.

In this article, expect to learn:

• What is Galvalume?
• The pros and cons of Galvalume
• What is galvanized?
• The pros and cons of galvanized

What Is Galvalume®? Definition, Uses, & Comparisons

Bethlehem Steel introduced the Galvalume coating to the construction industry in the early 1970s. Galvalume roofing material combines three of the most important metals used in roofing today—steel, aluminum, and zinc. Manufacturers begin with a carbon steel base sheet that is then continuously hot-dipped with aluminum and zinc alloys until it reaches a coating consisting of 55% aluminum, 43.4% zinc, and 1.6% silicone. This process allows for one material to have some of the best characteristics of each metal, which is why it’s become one of the most popular materials in today’s roofing market.

Galvalume is also referred to by its coating weights, AZ-50 and AZ-55. Here’s what these two terms mean:

• AZ-50 = 0.50 ounces per square foot of the aluminum-zinc alloy coating applied to both sides of the substrate.
  • AZ-50 is the typical coating weight for painted sheet/coil products.
• AZ-55 = 0.55 ounces per square foot of the aluminum-zinc alloy coating applied to both sides of the substrate. 
  • AZ-55 is the typical coating weight for bare or unpainted (often called acrylic-coated Galvalume or Galvalume Plus) sheet/coil products.
  • Acrylic-coated Galvalume has a slightly heavier coating weight and includes a light acrylic coating that protects the Galvalume coating in the manufacturing process. This acrylic coating will wear off over time with exposure. Though not painted, these products still need to be handled with care, or you risk scuffing or perforating the coating.

Uses for Galvalume® Metal Roofs & Walls

Overall, Galvalume is suitable as a roof, wall, trim, accent, and more in most building applications in some of the most extreme environments, including hurricane zones, locations with high rain or snowfall, high-temperature regions, and more.

Some common uses for Galvalume include:

• Commercial buildings – Hospitals, schools, stores, government buildings, and more
• Residential projects – Single-family, multi-family, condominiums, and more
• Architectural structures – Commercial, governmental, residential, and more
• Structural/industrial applications – Warehouses, factories, and more
• Agricultural – Non-animal confinement spaces, barns, storage, and more

However, there are some situations where Galvalume is NOT recommended for use. In these situations below, the main concern is that the coating will prematurely break down and cause the roof or wall system to fail quicker than if it were not in that location. Here are some circumstances where Galvalume should not be used:

• Animal confinement buildings – Galvalume is not suitable for use on buildings where animals are regularly housed or held. Manure from the animals breaks down into ammonia gas over time and then reacts with the Galvalume coating. This process breaks down the Galvalume coating and leads to degradation of the metal. However, Galvalume is sometimes used on modern chicken houses that are built with a vapor barrier between the chicken area and the roof for appropriate ventilation. It’s best to check with the manufacturer before putting Galvalume on an animal confinement building, as it depends on the specific use.
• In coastal environments – The coating of Galvalume will not stand up to the conditions associated with a coastal environment, including properties up against breaking surfs, large bays, marshes, and other coastlines. Specifically, a large amount of salt (sodium chloride) will harm the Galvalume coating and prematurely degrade the roof or wall system. It’s recommended that properties within a certain distance of a coast use an engineered aluminum roof system, as aluminum resists corrosion and rusting from saltwater for much longer.

Advantages & Pros of Galvalume®

Warranties – One of the number one selling points of Galvalume is the 25.5-year warranty on the substrate, which is sometimes referred to as a perforation warranty. Galvalume systems also often come with paint warranties that further protect your investment and provide peace of mind that the roof or wall system will last. (Note: Substrate or paint warranties are NOT available for Galvalume products within 1,500 feet of a coast.) Plus, commercial property owners can buy a weathertight warranty for their Galvalume roofing structure, which ensures the roof was installed correctly and adheres to strict installation details.

Corrosion resistance – When compared to galvanized metal, Galvalume’s corrosion resistance is about two to four times better. Galvalume’s formula was designed to combine the toughness and strength of zinc with the rust resistance of aluminum. Research conducted by the Metal Construction Association (MCA) indicates that Galvalume roofing could last as long as 40 to 50+ years without any extreme signs of corrosion. 

Self-healing properties – All steel-based products have some degree of edge creep from the exposed steel when the coil is cut, but it can be offset by hemming or touching up exposed edges with paint pens. An advantage of Galvalume that stems from this concept is the fact that it has self-healing characteristics that help control the red rusting at the cut/exposed edges. (Note: A small degree of red rusting at cut edges is normal, but with a Galvalume coating, the red rust will eventually stop.)

Economically priced – For the most part, Galvalume is reasonably priced and one of the more affordable metal materials available for roofing products. Depending upon the thickness, color, and quality of the desired Galvalume panels, pricing ranges anywhere from $5.00 to $15.00 per square foot. Keep in mind that in 2021 and 2022, steel prices are continually fluctuating, so the price can vary dramatically.

Disadvantages & Cons of Galvalume®

Oil canning – Oil canning is an inherent characteristic of light-gauge, cold-formed metal products, especially products with broad, flat areas. It’s a visual phenomenon seen as waviness or distortion in the flat surfaces of metal panels. Luckily, oil canning is only an aesthetic concern that doesn’t affect the performance of the roof system. This occurrence is possible with any metal roof or wall type, including Galvalume. However, there are methods to minimize the appearance of oil canning, including:

• Purchasing a thicker sheet or coil product (22 vs. 24 vs. 26-gauge).
• Buying trustworthy brands of coils and sheets.
• Rollforming panels with striations or bead stiffeners in the flat area of panels to minimize the appearance of oil canning.
• Hiring an experienced contractor who knows the best material handling and installation practices that help reduce oil canning.
• Ensuring there are no roof decking issues, as the metal will follow any inconsistencies on the deck.
  • If the roof deck is not in plane, it’s best to fix it beforehand to reduce the risk of oil canning.

Interactions with other materials – Combining different metals on a metal roof system can actually lead to interactions that could result in early degradation, staining, and potential failure of a system altogether. Galvalume performs best when not in contact with copper, lead, bricks, treated lumber, iron, and concrete. If Galvalume is in contact with one of these and is then introduced to an electrolyte, such as water, it can lead to galvanic corrosion of the metal.

Unpainted Galvalume scuffing concerns – When installing a non-painted Galvalume, the acrylic coating on the top of the panels is susceptible to scuffing, especially in high-traffic areas. Once the coating is scuffed, there’s not much that can be done to fix the issue other than immediately replacing the scuffed panels. If scuffed unpainted Galvalume is left on the roof, it may become splotchy as the scuffed/exposed parts of the roof age and weather quicker. To avoid this issue, it’s important to limit foot traffic on installed panels and be aware of foot, boot, and ladder placement.

What Is Galvanized Steel? Definition, Uses, & Comparisons

Galvanized metal products have been around since the 17th century, but the process of “galvanizing” materials became a widespread practice in the early 19th century. Galvanization (commonly referred to as galvanized) is a protective zinc coating that is applied to a steel or iron substrate through a hot-dip galvanizing process. Before the introduction of Galvalume to the metal roofing industry in the late 20th century, using galvanized sheet and coil was a common practice. However, because of the superior durability and corrosion resistance of Galvalume, 90+ percent of the metal roofing and wall industry in the early 2000s transitioned from galvanized substrates to a Galvalume substrate.

Additionally, galvanized metal sheet/coil may also be called G-90, which refers to the coating weight.

Uses for Galvanized Metal Roofs & Walls

Galvanized metal is used in similar applications as Galvalume, especially for agricultural projects. However, the most significant thing to keep in mind is that galvanized is a little more challenging to find and might depend on what area your project is in (more details on that below). As mentioned, most manufacturers have stepped toward using Galvalume as the majority of their product offerings because it lasts longer and provides more benefits for property owners.

At Sheffield Metals, we do carry one product that has a galvanized substrate, Vintage® from Steelscape. To this day, Vintage is a popular sheet and coil, especially for architectural applications where an aged metallic look is desired.

Additionally, galvanized products will not stand up to the conditions associated with a coastal environment, including properties up against coastlines with breaking surfs, large bays, and marshes. Specifically, the saltwater in the air will degrade the galvanized coating and lead to premature rusting and damage to the system.

Advantages & Pros of Galvanized

Better suited for animal confinement – One of the most notable benefits of galvanized steel is that it can be used on structures that house animals. Galvalume is not suitable for animal confinement because manure from the animals breaks down into ammonia gas over time and then reacts with the Galvalume coating. However, an adequately ventilated galvanized roof system can perform well for several animal confinement applications. It’s best to check with the manufacturer before putting galvanized steel roof on an animal confinement building; plus, they might offer some specific design recommendations.

Better formability – Galvanized steel is more malleable than Galvalume, meaning that it will bend and form a little easier than other metal types. This is why galvanized is sometimes used more often in stamped metal shingles or stamped vent flashings, as galvanized allows for more concise bends.

Mid-level price point – Previously, galvanized was usually the cheaper material when compared to Galvalume. However, in the last 10+ years, the pricing of these two materials has fluctuated back and forth, but predictions in 2022 show galvanized material is now about 6% higher in price over Galvalume. Typical G-90 galvanized standing seam metal roofs cost anywhere from $8.00 to $16.00 per square foot and fluctuate further based on your location, the installer, the material color, thickness, and more. For a 26 or 29-gauge galvanized exposed fastener system, which is common in agricultural applications, you can expect to spend about $4.50 to $7.50 per square foot. Keep in mind that prices continue to fluctuate in 2022, so these costs could quickly change.

Disadvantages & Cons of Galvanized

No substrate warranties – Arguably the most significant disadvantage to galvanized metal systems is the fact that the substrate doesn’t have a warranty. Most galvanized systems have the potential to be unpredictable in specific environments and use, meaning that most manufacturers don’t offer warranties on most galvanized products. 

Not self-healing & red rust – The zinc coating on galvanized sheet/coil does a good job protecting the steel core for the first decade or so of use. Though once any part of the steel core is exposed, the metal will start to red rust, which is both unsightly and will eat away at the metal over time. As we discussed, all steel products inherently have some degree of edge creep near cuts and exposed edges. The problem with galvanized metal (painted or not) is that once it starts to red rust, it doesn’t eventually stop as Galvalume does. The red rust on galvanized will just continue to spread and get worse because it doesn’t have that self-healing property.

Shorter longevity – Studies have shown that galvanized metal roofs will last around 15-20 years in the right environment. This may seem like a long time, but you would expect it to last as long if you’re spending the same amount or more for a galvanized roof than for a Galvalume roof. However, Galvalume roofs can last 40+ years, which is over double the lifespan of a galvanized roof.

Availability issues – When compared to Galvalume sheet and coil products, galvanized metal roofing products aren’t always as accessible. Galvanized is a very regional product, meaning that it’s easier to find and purchase in specific areas of the U.S., including those with a higher concentration of agriculture and animal confinement. Since Galvalume tends to perform better and lasts quite a bit longer, it’s easier to find and purchase nationwide.

Oil canning – Like Galvalume, galvanized metal can also develop oil canning in the flat areas of the panel.

Final Thoughts on Galvalume® vs. Galvanized

Even though Galvalume and galvanized are generally similar in the way they’re created, they have different characteristics that affect how each one should be used in metal roof and wall projects. 

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Here’s a recap of what we discussed:

Galvalume is:

• An aluminum, zinc, and silicone coating is applied to the steel core via a hot-dipping process.
• Often offered with paint, substrate, and weathertight warranty options and has self-healing properties.
• Susceptible to oil canning, like galvanized metal.

Galvanized is:

• A zinc coating hot-dipped onto a steel core with origins dating back to the 17th century.
• Often not warrantied due to unpredictability and can develop excessive red rust when a core metal is exposed.
• Not likely to last more than 20 years, despite being more expensive than a 40+ year Galvalume roof.

At Sheffield Metals, we are dedicated to providing and educating our customers with the information they need to make the best and most informed decision. Contractors, architects, distributors, homeowners – we’re available to help with your metal roofing project.

Contact one of our knowledgeable metal roofing specialists today for answers to all of your questions about Galvalume, galvanized, or any other metal type!

When deciding what material to purchase for your metal roof in Florida, you may have come across various options like steel, copper, aluminum, galvanized, and Galvalume. 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.

Why choose a metal roof in Florida?

Overall, the main advantage of using a metal roofing material in Florida and coastal regions is its ability to withstand harsh weather conditions, including wind, rain, and saltwater corrosion. However, each type of metal roofing material has its own unique advantages, and choosing the right material depends on factors such as budget, aesthetics, and performance requirements. A qualified manufacturer and supplier of different metal roofing types and materials can provide valuable advice for your particular project.

Galvalume vs Galvanized vs Aluminum

Here are three popular types of metal roofing materials in use today:

Galvanized Steel Roofing

Galvanized steel is a type of steel that has been coated with a layer of zinc to protect it from corrosion. The process of galvanization involves immersing the steel in a bath of molten zinc or applying a zinc coating through electroplating. The zinc coating acts as a sacrificial layer, meaning that it corrodes before the underlying steel, providing protection against rust and extending the lifespan of the steel. Galvanized steel is relatively low in cost compared to other corrosion-resistant materials, but may not last as long before showing signs of corrosion.

Galvalume Roofing

Galvalume is a steel-based roof coating type that includes aluminum, zinc, and silicon that is up to twice as resistant to corrosion as galvanized steel. 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 painted in a variety of colors. As one of the most popular roofing materials on the market today, it’s impressively durable. It is a low-maintenance material that will last for at least 40 years, providing significant savings throughout its lifetime.

Aluminum Roofing

While Galvalume provides good corrosion resistance due to its zinc-aluminum alloy coating, aluminum roofing offers even greater resistance to corrosion. Aluminum is inherently resistant to rust and corrosion, making it an excellent choice for areas with high moisture or salt exposure, such as coastal regions. Both aluminum roofing and Galvalume have long lifespans, but aluminum is generally considered to have superior longevity.

Applications

Where Should Galvalume Roofing Be Used?

The main purpose of a Galvalume coating is to protect steel from oxidizing (rusting), which compromises the integrity of the material. It may 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. Thanks to its corrosion-resistant properties, Galvalume is ideal for humid and hot environments, commercial buildings, residential homes, storage units, and more, making it an affordable, low maintenance roofing material choice in many areas of Florida.

Where Should Aluminum Roofing Be Used?

Aluminum is preferred to Galvanized or Galvalume steel in coastal areas, as the elemental metal is more resistant to saltwater-induced corrosion and rusting. 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 on properties along the coastline, near large bays, surf breaks, and marshes. Aluminum is also highly malleable and can be easily formed into various shapes, profiles, and designs that gives architects and homeowners more flexibility in creating customized roof designs. Galvalume, being a steel product, has some limitations in terms of formability and design options.

Where Should Galvanized Steel Roofing Be Used?

Galvanized metal roofing is better suited for dry climates, free of pooling water and salt air environments which limits its broad application in Florida. Galvanized or pre-galvanized materials or insulated metal panels are a preferred choice for lower value applications such as outbuildings or barns. As a rule, Galvalume is not ideal for buildings used to house or enclose livestock, as 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.

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.

Metal Roofing Wear

Although the wear of metal roofing is vastly superior asphalt, over time it can exhibit some wear characteristics that you should know about.

• Oil Canning
  Oil canning refers to the visible waviness or distortion on the flat surface of a Galvalume, painted or aluminum 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 the roof’s strength, durability, performance, or lifespan. 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 impact the overall appearance of the structure.
• Scuff Risk
  On painted or unpainted metal materials including Gavalume and aluminum, it’s important to know that its coating can scuff, leaving an exposed portion of the metal panel that ages and weathers faster due to the lack of a protective layer. While many prefer the performance of Kynar painted panels, it is a softer finish than our standard WeatherXL paint and can be more easily damaged by foot traffic and environmental wear factors. Since you cannot fix a 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.
• Galvalume 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. For this reason, it’s also important to use a compatible screw material on any metal roof. 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.

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.

What Roofing Material Lasts the Longest?

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. Both Galvalume and aluminum roofing have long lifespans, but aluminum is generally considered to have superior longevity. Aluminum roofs can last for many decades without significant degradation, whereas Galvalume roofs typically have a slightly shorter lifespan. For the greatest lifespan, select stainless steel or aluminum roofing materials.

What Has a Better Warranty?

Virtually all aluminum and 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.

What Material is Most Affordable?

Because galvanized and Galvalume steel are made in a similar fashion, they’re sold at a similar price, though some lower grades of galvanized steel are available for less expense. Aluminum roofing is a premium product that offers higher performance and lifetime, but also a higher cost. Metal roofing is often more expensive than asphalt shingles, but the long-lasting nature of the products means they are usually more cost-effective overall and save the homeowner money long term.

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.

The Bottom Line

Here are the differences and advantages of each roofing material in Florida and coastal regions:

• Galvanized steel: Galvanized steel is coated with a layer of zinc to protect against corrosion. However in Florida, humidity and salt air can accelerate corrosion on galvanized steel so it’s not recommended for long-term durability in residential applications. Its advantages include affordability, ease of installation and a classic look.
• Galvalume: Galvalume is a popular choice for many Florida regions because of its enhanced durability and ability to withstand corrosion better than galvanized steel. In addition, Galvalume roofing is generally less expensive than aluminum roofing. If cost is a primary consideration, Galvalume may be a more budget-friendly option.
• Aluminum: Aluminum is a premium lightweight metal that is inherently resistant to rust and corrosion. It is the preferred choice for coastal regions due to its higher resistance to saltwater corrosion and superior longevity. Other advantages include durability, low maintenance and higher energy efficiency due to its reflective surface.

Ultimately, a choice between Aluminum roofing vs Galvalume depends on factors such as the specific application, budget, desired aesthetics, and environmental conditions. Both materials offer corrosion resistance and durability, but aluminum roofing excels in terms of superior corrosion resistance, lighter weight, and enhanced thermal performance.

We can help

Choosing the right metal roofing materials 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 or Aluminum sound like the right choice for your next project? Contact 1st Coast Metal Roofing Supply to order your high-quality materials. We’re happy to answer any of your questions about metal roofs and offer help you decide if you’re still comparing Galvalume vs galvanized or aluminum roofs. Get in touch with us today for a free quote.

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About 1st Coast Metal Roofing Supply

Protect your home from Florida’s extreme weather conditions with durable and reliable metal roofing solutions from 1st Coast Metal Roofing Supply. As the leading metal roofing manufacturer and supply company based in Florida, we offer a wide range of high-quality roofing materials that are designed to withstand hurricane-force winds, tropical rainfalls, and the harsh UV effects of intense sunlight. With our expert guidance and exceptional customer service, you can trust us to provide you with a roof that not only looks great but also lasts for years to come.

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