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What Goes Into a DECRA Metal Roof?

Mark Gallant • November 16, 2020

What Goes Into a DECRA Metal Roof?


What Goes Into a DECRA Metal Roof?

In the 1940s, the Decraspray company was commissioned to develop a granular spray coating to camouflage shiny metal roofs in Allied military installations to protect them from Axis air raids. 

After the war, removing the Decraspray coating from the metal roofs beneath proved to be quite a daunting task. When the Decraspray coating was eventually pried away, it was revealed that the underlying metal roofs were completely free from corrosion after years of exposure to the harsh seasonal extremes of the UK’s notorious North Atlantic weather. 

This is how the stone-coated metal roofing concept was born. In 1957, DECRA Metal Roofing introduced the first stone-coated metal roofing product and set on a path of innovation that would continuously disrupt the conventional roofing material industry. With lifetime durability and the versatility to replicate nearly any traditional roofing style, DECRA has set the gold standard for the roofing industry.

So how does DECRA manufacture stone-coated steel roofing products that last a lifetime?

The DECRA Hot-Dip Process With 55% Aluminum, 43.4% zinc, and 1.6% Silicon

All DECRA roofing products are precisely formed from 55% aluminum-zinc alloy coated steel. High-grade, cold-rolled carbon steel is treated with a hot-dip process metallic coating composed of 55% aluminum, 43.4% zinc, and 1.6% silicon. Both sides of the steel sheet are coated to optimize corrosion resistance. 

While the aluminum and zinc alloy components combine to provide outstanding corrosion resistance, the silicon enhances the alloy coating by increasing the adhesion of the microscopic metallic alloy particles in the coating. Silicon is a unique metalloid -- one of only a very few elements that have characteristics of both metals and nonmetals.

That crucial 1.6% silicon in the DECRA formula is important to ensure that the protective coating remains firmly fixed to the steel to endure bending both in the manufacturing process and in challenging installations on buildings which include towers, turrets, cupolas, and other complex architectural elements. 

Exceptional alloy coating adhesion with silicon gives DECRA roofing profiles the versatility to replicate the forms and textures of traditional roofing materials including:

DECRA Villa Tile: Barrel-style Old World clay tile
DECRA Tile: Elegant scalloped edge tile
DECRA Shingle XD: Replicates the rich dimensions of thick-cut shingles
DECRA Shake XD: Rustic detail of traditional hand-split wood shakes
DECRA Shake: The texture and appeal of the best red cedar shakes

55% Aluminum-Zinc Alloy Coated Steel

Zinc and aluminum both have excellent anti-corrosive properties, but they work even better when combined together in the DECRA formula that provides significantly extended corrosion resistance. 100% zinc coatings are also known as “galvanized steel” but without the aluminum alloy component, the corrosion protection of zinc alone degrades quicker over time. 

That is why DECRA uses an advanced 55% aluminum-zinc alloy coating with a lifetime that’s up to 4 times longer than traditional galvanized steel. Zinc provides exceptional bare-edge protection for cuts and drilling, but 100% zinc coatings are what engineers call “sacrificial”. That means that corrosion will eventually find its way into the steel sheet over time. When the zinc’s sacrificial barrier eventually begins to break down first, the more durable aluminum component in the alloy ensures that an effective corrosive barrier is still present. 

But not all aluminum-zinc alloys are created equal. 

AZ50 vs AZ35

The minimum industry quality standard for coating thickness is known as AZ50. 

AZ50 specifies that there is a minimum coating weight of 0.50 ounces per square foot on both sides of the steel sheet. 

But some overseas manufacturers produce imitation DECRA products using a cheaper AZ35 alloy -- a much thinner coating highly susceptible to degradation by corrosion, especially when installed on roofs in a corrosive salt-air rich environment such as coastal areas.  

Thermal Performance Advantages With 55% Aluminum

An additional benefit of the aluminum component is its superior heat reflective properties which result in significantly reduced solar heat gain that no conventional roofing material such as asphalt shingles, wood shakes, or clay tile can match. That exceptional reflective thermal performance increases energy efficiency to allow DECRA homeowners to save on heating and cooling expenses. 

Advanced Acrylic Resin Coatings

DECRA uses a state-of-the-art acrylic resin coating applied on both sides of the aluminum-zinc alloy hot-dip steel coils used to produce all DECRA Metal Roofing roof panels and accessories. 

The brown-tint resin coating is specially formulated to resist fingerprints and scuffing during product handling, The acrylic resin coatings also provide a superior surface for augmenting the adhesive properties of the durable acrylic mastic that DECRA applies to adhere the stone granules offering vivid colors and distinctive textures to the base steel sheets.

Sustainability With DECRA

Sustainability has become a high priority in modern construction. More new environmental laws and regulations at all levels of government are coming into effect that require energy efficiency, reduction of carbon footprint, and increased use of recyclable construction materials.

DECRA’s 55% aluminum-zinc alloy coated steel is 100% recyclable and uses up to 30% recycled materials in the manufacturing process, which can then be melted back down for reuse at the end of their life cycle. 

About DECRA Metal Roofing 

Our outstanding product quality is matched by our operational excellence. DECRA products are manufactured right here in the U.S. at our state-of-the-art facility in Corona, California. We test all of our products above and beyond what is required to ensure that each and every DECRA Metal Roofing panel lasts a lifetime. 

When you’re ready to protect your home or business for a lifetime, contact an expert DECRA advisor today