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Do Metal Roofs Rust?

Do Metal Roofs Rust?

To answer this question, it’s important to note that not all metal roofs are created equal. The rusty roof on your neighbor’s shed? That’s a sheet of corrugated metal. If you’re going for the rustic look, you can even buy pre-rusted corrugated metal roofs to fit the style of your home or building. 

Not interested in the rusted or rustic look for your home or building? Then a DECRA metal roof is for you. DECRA Metal Roofing products have a proven, long-life alloy formula that protects your roof from rust and corrosion for a lifetime. 

Let’s take a look at the metallurgy properties that make a DECRA metal roof more resistant to rust and corrosion.

The DECRA Stone-Coated Steel Difference 

Aluminum and zinc are two of the best metals for preventing corrosion and perform even better when combined in an alloy coating. DECRA metal roofs are manufactured from cold-rolled high-grade carbon steel with a continuous hot-dip process aluminum-zinc coating applied to both sides of the sheet. The DECRA anti-corrosion alloy formula for lifetime endurance against rust and corrosion is:

 55% aluminum, 43.4% zinc, and 1.6% silicon. 

The corrosion-resistant alloy coating is applied to both sides of the steel sheet to meet the rigorous DECRA Metal Roofing AZ50 standard for endurance and durability

Zinc and Aluminum Alloy Coating With Silicon

The zinc in the alloy coating initially protects the steel, including “healing” cut or drilled edges, but will gradually corrode away over time. DECRA engineers have prepared for this inevitable event commonly known as “sacrificial coating”. 

That’s where the 55% aluminum content in the alloy becomes so important. 

Once the zinc coating is “sacrificed” after many years of exposure to the elements, the aluminum component of the metallic alloy coating still stands strong. The high aluminum content ensures that a barrier against corrosion remains in effect for a substantially longer period of time.  

That leaves us with the small but important 1.6% silicon content in DECRA’s corrosion-resistant formula. The silicon component provides superior alloy coating adhesion. This helps the coating remain firmly in place while the high-grade carbon steel is rolled, stamped, or bent. 

But DECRA Metal Roofing doesn’t just settle for the best 55% aluminum-zinc alloy for corrosion resistance, we take things a step further to ensure the highest quality product. 

DECRA Acrylic Water-Based Resin Coating

DECRA applies a brown-tint resin coating that is specially formulated to resist damage during product handling. This durable acrylic resin also eliminates the need for steel roll forming lubricants to be used in the coil production process that could leave trace residues that cause bonding problems later in the manufacturing process. 

The acrylic resin coating also delivers a superior adhesion surface for attaching the stone granules to the base steel sheet. This is a must for stone-coated steel panels that can bend and form to the contours of roof designs featuring towers, cupolas, or any type of exotic geometry. 

The result of the DECRA 55% aluminum, 43.4% zinc, and 1.6% silicon combination is a metal roof system that outperforms every conventional roofing material. And when the end of the DECRA roof lifespan does eventually come sometime in the next century or longer, the zinc-aluminum alloy panels are 100% recyclable. 

Beware of Imitation Products

As you’ve learned, the metallic alloy coating of a metal roof is critical to resisting rust and corrosion. Beware of sites like Alibaba that host a profusion of overseas “Decra” imitators who may skimp on zinc-alloy thickness in their coatings and manufacture from raw materials of dubious quality. 

DECRA stone-coated steel roofing products are manufactured at our state-of-the-art facility in Corona, California. To ensure your home or building stays rust and corrosion-free for a lifetime, make sure that you’re using genuine DECRA Metal Roofing products.  

Ready to see how a DECRA metal roof will look on your home or building? Upload an image of your property to our “Design My Roof” visualizer app