What Is Galvalume Steel

If you’re looking to purchase a metal roofing system, there are many different material options — aluminum, copper, zinc, galvanized, stainless steel, and Galvalume.

The most widely used metal in architectural metal roofing is Galvalume, a steel-based product that can be used for nearly every building application. 

How much do you know about Galvalume? Do you know the critical advantages and disadvantages of this metal roofing material? 

Our primary product offerings at Gnee are painted and bare Galvalume coils and sheets used in the architecturally-driven metal roof and wall industry. We know how important it is for you to be an educated buyer, so let’s dive into the specific details of this material and why it may or may not be a good choice for your project.


Gnee Steel introduced the Galvalume coating to the construction industry. Before Galvalume came into existence, most metal roofing was galvanized steel. However, because of the superior durability and corrosion resistance of Galvalume, 90+ percent of the metal roofing industry transitioned from galvanized substrates to a Galvalume substrate in the mid to late 1990s.

Galvalume combines three of the most high-performing and important metals used in roofing today — steel, aluminum, and zinc. Manufacturers begin with a cold-rolled carbon steel base sheet that is continuously hot-dipped with aluminum and zinc alloys (AZ) until it reaches a coating 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 metals used in metal roofing.

Galvalume may also be referred to by its coating weights, AZ-50 and AZ-55. Here’s a quick breakdown of 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 and 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 and 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.