When you’re looking into metal roofing, you’ll quickly come across two types in particular: Galvalume® and galvanized. We are often asked by customers about what metal to use since we’ve spent the past two decades manufacturing roofing and siding panels made from these different types of metal.
While both of these metal options are similar in some ways, they do have some differences you need to be aware of.
Before we talk about the differences of each roofing material, let’s briefly touch on their similarities.
Both Galvalume® and galvanized are coated metal products that are used for both roofing and siding. They are very similarly priced, so cost will not be a deciding factor when choosing between the two materials.
Below we will discuss the pros and cons of each material.
Galvanized metal is a steel that is coated with rust-inhibiting zinc that protects the steel core from corrosion. The thicker the layer of zinc, the longer you have before it corrodes away and exposes the steel substrate.
Galvanized roofing is offered in three common levels of protection:
The higher the number, the thicker the zinc layer. Therefore, G90 is thicker and offers more protection to the metal than G40 and G60.
A galvanized metal roof is more affordable when compared to most treated steels.
Galvanized steel is immediately ready to use when delivered. It does not require additional preparation of the surface including painting/coatings etc. which saves you time and labor.
Both galvanized and Galvalume are shiny materials, however galvanized metal has a much shinier surface. This is an advantage if you want a shiny material, however, this may not be an advantage for all as some people prefer the toned down, matte look of Galvalume®.
Consider the look you want to achieve for your roof when deciding between the two metal materials.
Galvanized coatings will perform better than galvalume in facilities that house livestock. The animal urine has less of an affect on galvanized vs Galvalume®.
Galvanized metal is corrosion resistant. However, that resistance does not last forever. Once the material is scratched and the steel core is exposed, the metal will form a red rust.
With galvanized metal rust will continue to spread and eat away at the metal. This negatively affects the looks and the function of the metal.
Galvanized metal does not have the same corrosion protection as Galvalume®.
Because of the issues we’ve previously mentioned about galvanized metal including it’s shorter lifespan, the roofing industry has been pulling away from using galvanized metal. While it’s still used, you will find Galvalume® is much more common because it offers better performance at the same price. As a result, galvanized metal is harder to find.
Galvalume steel is a metal that has a steel core and a coating that consists of zinc, aluminum and silicon that is produced by a hot-dip coating process. The coating protects the steel from oxidizing.
Galvalume® was introduced into the market long after galvanized metal. However, it’s superior performance quickly made it the more preferred material, and today Galvalume® is much more commonly used as opposed to galvanized metal.
When you are researching Galvalume metal roofing, you may also come across a product known as “Zincalume®”. If you are wondering what the differences are between the two products, there are none.
Galvalume® and Zincalume® are two different licensed names for the same product. Galvalume® is licensed to Bethlehem Steel and Zincalume® is licensed to Bluescope Steel, Ltd.
Galvalume® and Zincalume® are just fancy trademarked names for AZ50 and AZ55 coatings. Simply put, it means that either .50 ounces or .55 ounces per square foot of the aluminum-zinc alloy coating has been applied to both sides of the metal sheet.
Since the coating on AZ55 is thicker than on AZ50, it means that AZ55 also offers better protection for the metal than AZ50.
Galvalume® is often supplied with a thin, clear acrylic coating. Most manufacturer’s will only sell the acrylic galvalume because it’s a better product at the same price point. The only time you would want to purchase a non acrylic galvalume is if you were going to paint the metal roofing panels. We go over the differences between using acrylic or no acrylic below.
Galvalume comes with a 20 year sheet producer warranty, and painted products can often have a paint warranty that extends beyond that time frame depending upon which paint system is used. Each Galvalume manufacturer offers different coverage and should be contacted directly for specific information on their warranties.
Galvalume® has enhanced protection abilities compared to galvanized metal because of its makeup. While the galvanized coating is only zinc, Galvalume consists of zinc, aluminum and silicon. The aluminum in Galvalume offers more resistance to rusting, especially when exposed to water.
Galvalume-coated metal is less likely to rust than normal galvanized metal.
It’s common for steel roofing materials to have some “edge creep”, or corrosion of metal roof edges, near where the panel was cut. This leaves a small part of the steel exposed which results in rust.
Galvalume is “self-healing,” meaning it eventually stops the rust from spreading over the panel. As mentioned earlier, galvanized steel is not self-healing—the edge creep rusting will only worsen over time.
Farms and animals tend to go hand in hand. However, if you’re building a structure on a farm that will come into contact with animals, specifically animal urine, you want to avoid Galvalume®.
While animal waste does not go well with any type of material, Galvalume® will corrode exceptionally faster than galvanized metal when exposed to animal urine. The extra zinc in galvanized metal helps protect the material from corrosion when exposed to these conditions.
When using Galvalume®, you have to consider the other materials you are using. Using dissimilar materials with Galvalume® can result in galvanic corrosion, which may cause the roof to fail prematurely.
Examples of material that should not be used with Galvalume® include:
Now that we’ve gone over the pros and cons of each metal, let’s summarize the differences between the Galvalume® and galvanized:
|
Galvanized |
Galvalume® |
|
|
Coating Material |
Zinc |
Aluminum, Zinc, Silicone |
|
Self- Healing |
No |
Yes |
|
Warranty |
Maybe |
Yes |
|
Finish |
Shiny |
Less Shiny |
|
Availability |
Limited |
Available |
Galvalume® and galvanized metal roofing, which are both about the same price, are the most affordable metal roofing panels. When you want to get away from the shiny look of Galvalume® and used painted metal panels, the price is going to increase.
Remember, prices for panels will vary depending on steel market conditions, thickness of the metal (gauge) and the type of paint system when choosing a painted metal roof.
Below is a price range of what to expect for material cost only:
|
Galvalume® Metal Panel |
Painted Metal Panel |
|
|
24 Gauge Corrugated |
|
|
|
26 Gauge Corrugated |
|
|
As we stated several times throughout the article, Galvalume® is much more commonly used and preferred compared to galvanized metal. However there are circumstances, like being used in agricultural areas with animals, where Galvalume should not be used.
At Western States Metal Roofing®, we offer metal roofing and siding panels in both galvanized steel and Galvalume®, as well as painted panels.
Download our color guide to see the panels we have available and request a sample of your favorite choices.