What to know about galvanized steel roofing vs galvalume steel roofs

Galvanized steel and Galvalume are both popular choices for metal roofing in residential, agricultural, and commercial applications. Knowing the materials’ characteristics can help you make the most appropriate selection. Getty Images

Whether you're buying a metal roof for your home, your barn, or your business, it’s important to understand the type of material you’re buying. Your roof protects you and your possessions from the elements, so you want to be sure to select the very best material for your specific needs—and that requires knowledge of the different types of metal roofing.

When you begin the process of outfitting your building with a metal roof, you will likely hear many unfamiliar terms. Two of those might be galvanized steel and Galvalume. Which one is best for your structure?

Galvanized steel has been used in building for nearly 200 years. In fact, the first use of the term occurred in France in 1836, when inventor Stanislas Sorel filed a patent for the galvanizing process.

Today, galvanized steel is created in the same way it was in Sorel's time. A piece of steel is cleaned and dipped into molten zinc. The zinc then hardens onto the steel, creating an extra protective coating. This helps the steel stand up to rust, corrosion, nicks, and dents.

Galvanization is used widely around the world; according to the American Galvanizers Association, galvanizing uses more than 600,000 tons of zinc annually in North America alone.

In the 1970s U.S. shipbuilding company Bethlehem Steel decided to expand upon Sorel's invention. It added metals to molten zinc and began to experiment with creating a mixture that would yield even greater protection. Ultimately the company settled on an ideal mixture, and Galvalume was born.

Galvalume (a registered trademark of BIEC Intl. Inc., the licenser of the technology) is a coating of 55% aluminum, 43.4% zinc, and 1.6% silicone over steel sheet. The coating gives the steel greater protection from the elements, allowing it to outlast traditional galvanized steel.

Not only do Galvalume roofs and walls tend to outlast the elements, but they also have a self-healing feature. If the steel begins to rust along a cut or exposed edge, the coating can stop the rust from spreading.

The main difference between Galvalume and galvanized steel is the protective coating around each steel sheet. Galvanized steel is coated in zinc, while Galvalume is coated in zinc, aluminum, and silicone.

Both are excellent for roofing, and each has pros and cons. Galvalume is a much longer-lasting material, with a lifespan about twice that of galvanized steel. Galvanized steel tends to cost less (while still delivering great protection), making it a suitable choice for buyers on a budget.

Galvanized metal is ideal for agricultural spaces like barns or storage buildings, and even residential homes. The extra durability that galvanized steel offers provides superior protection from the elements, and galvanized steel can be painted to suit your building design or aesthetic.

Galvalume is also ideal for residential homes, commercial buildings, and agricultural spaces. However, it is especially useful in places where extreme weather conditions are more likely to occur. The extra protection that comes from Galvalume will keep your roof in better condition after years of snow, rain, high winds, and wide-ranging temperatures.

It’s always best to talk to a local expert with experience in Galvalume and galvanized steel. An experienced professional can provide the best recommendation based on the intended use of your building and the expected weather conditions in the area.

No matter what you decide, a steel roof will last longer and provide more protection than wood or asphalt shingles. With a steel roof, whether galvanized or Galvalume, you can enjoy durability, safety, and energy efficiency for years to come.

Brian Haraf is vice president of sales and marketing for Metal Sales Manufacturing Corp., 545 S. 3rd St., Louisville, KY 40202, 502-855-4300, www.metalsales.us.com.