Galvanized vs. Galvalume®: What’s the Difference?

Not all metal panels are created equal. That's why educating yourself and understanding your options is essential. The substrate beneath the paint system can significantly affect the long-term performance of a metal roof or wall panel.

Galvanized and Galvalume® are two of the most common steel substrates used for metal roofing and siding. While both protect against corrosion, they differ in important ways.

Let's take a closer look at Galvanized and Galvalume® and where each makes the most sense.

What Is Galvanized Steel?

Galvanized steel has been used in construction for decades and is created by coating steel with zinc. The zinc coating helps protect the underlying steel from corrosion.

However, not all galvanized products are the same. The amount of zinc applied to the steel directly affects its corrosion resistance and long-term performance.

Two common galvanized substrates are G60 and G100. The numerical designation refers to the total amount of zinc applied to both sides of the steel. G60 contains 0.60 ounces of zinc per square foot, while G100 contains 1.00 ounce per square foot.

That means G100 contains approximately 66% more zinc than G60. Because zinc provides corrosion protection, higher coating weights generally deliver better long-term performance.

What Is Galvalume®?

Galvalume® was introduced in the early 1970s and combines the benefits of aluminum and zinc in one coating.

Most Galvalume® substrates feature an alloy consisting of approximately 55% aluminum, 43.5% zinc, and 1.5% silicon. The aluminum provides barrier protection, while the zinc helps protect exposed steel from corrosion.

This combination gives Galvalume® excellent long-term corrosion resistance and, for most applications, outperforms Galvanized steel.

Galvalume® is commonly available in two coating weights: AZ50 and AZ55. AZ50 is the industry-standard coating level for painted products, while AZ55 is commonly used for bare or unpainted panels.

These designations refer to the total amount of aluminum-zinc coating on both sides of the steel. AZ50 contains 0.50 ounces per square foot, while AZ55 contains 0.55 ounces per square foot.

Is Galvanized or Galvalume® Better?

So which is better? That depends on the type of project. For animal confinement projects, we recommend Galvanized panels. Animal waste can create a highly corrosive environment, and the aluminum in the Galvalume® coating can react negatively in those conditions.

Using a Galvanized product with a higher zinc coating weight is also important for animal confinement projects. For that reason, G100 is typically a better choice than products with lower zinc coating weights.

Outside of animal confinement projects, we generally recommend Galvalume® substrates. That recommendation is based on decades of testing and actual field performance demonstrating Galvalume®'s improved long-term corrosion resistance compared to Galvanized products.

Steel mill substrate warranties also back Galvalume® performance against rupture or perforation due to corrosion. Similar steel mill substrate warranties are not typically available for Galvanized products.

How Do You Choose Between Galvanized and Galvalume®?

Choosing the right substrate starts with understanding the project and the environment where the panels will be installed.

For most residential, commercial, and architectural roofing and wall applications, Galvalume® provides excellent long-term corrosion resistance and is our recommended substrate.

For animal confinement buildings, Galvanized, preferably with a higher zinc coating weight such as G100, is generally the better choice.

The key is to look beyond the panel's appearance. Understanding the substrate and coating weight can help you select a product that delivers the performance your customer expects.

We're proud to offer both Galvanized and Galvalume® substrates, giving our customers the flexibility to choose the right material for their projects.

If the manufacturer you're working with doesn't offer your desired substrate, contact us. We're happy to help!