How are Metal Roofs Made?

By Mark Gallant, DECRA Metal Roofing. 

Learn why DECRA metal roofs are so durable and long-lasting. 

Metal roofs are among the most popular of roofing materials on the market due to their many benefits, but what are they made out of? Besides the obvious answer (metal), much more goes into DECRA Metal Roofing products to give them the durability and quality they are known for. Continue reading to understand why these materials make a metal roof so special. 

Aluminum-zinc alloy coated steel 

All DECRA roofing products are precisely formed from structural quality sheet steel complying with ASTM Designation A 792/A 792-10; grade 37, modified with a minimum elongation of 22%, and with an AZ50 coating class. 

The high-grade steel used in DECRA products is treated with a hot-dip metallic coating composed of aluminum, zinc and silicon. 

Both aluminum and zinc have excellent anti-corrosive properties, but they work even better when combined together. 

For example, a coating of 100% zinc (also known as galvanized steel) provides exceptional bare-edge protection for cuts and drilling. But, 100% zinc coatings are what engineers call “sacrificial,” meaning that corrosion will eventually find its way into the steel sheet over time. 

That is why DECRA uses an advanced aluminum-zinc alloy coating that protects up to four times longer than traditional galvanized steel. When the zinc’s sacrificial barrier breaks down over time, the more durable aluminum component in the alloy ensures that an effective corrosive barrier is still present. 
 
While the aluminum and zinc alloy components combine to provide outstanding corrosion resistance, the silicon in DECRA’s formula ensures the protective steel coating remains firmly fixed to the steel. Silicon also allows for bending during the manufacturing and installation processes. 

It’s important to note that not all aluminum-zinc alloys are created equal. 

For example, AZ50 is the minimum industry quality standard for coating thickness and 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 that is highly susceptible to degradation by corrosion, especially when installed on roofs in a salt-air rich environment, such as coastal areas. 

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. 

The brown-tint or clear resin coating is specially formulated to resist fingerprints and scuffing during product handling. The acrylic resin coating also provides the ideal surface for adhering the stone granules to the base steel sheet. 

Stone-coated granules 

DECRA’s stone-coating manufacturing process bridges the gap between industrial durability and design versatility. 

Adding stone granules allows DECRA to produce a wide range of roofing styles, colors and textures that replicate the look of traditional roofing materials such as asphalt shingles, tile or wood shake. 

The natural stone granules are mined at a quarry, then crushed and screened to size. The granules are then coated with a combination of pigments, similar to paint, and then baked at high temperatures. 

Given the intense solar UV exposure on a roof, the roofing granules must be durable and fade-resistant, which is why DECRA utilizes a leading roof granule source and state-of-the-art computerized roofing granule blending and application machinery to ensure a quality stone coat manufacturing process. 

For example, using a spectrophotometer, several color readings are conducted at different intervals during the manufacturing process to ensure the pigmentation has adhered properly to the stone granule. This also ensures that the color will remain stable over time. 

In addition to the high-quality steel, stone granules and manufacturing processes, DECRA takes pride in conducting extensive, lab-verified testing to ensure the quality that our roofs are known for is present in each and every panel. 

Extensive testing 

As the original stone-coated metal roofing manufacturer, DECRA’s formula has withstood the test of time and has set the industry standard for quality since 1957. 

DECRA’s reputation for quality comes from the fact that we submit all products for independent lab testing above and beyond what is required. Most roofing manufacturers strive to satisfy just the minimum U.S. building code requirements, narrowly focused on wind and fire resistance. 

For example, many of our competitors, especially overseas manufacturers, don’t offer their products in Canada since the weather conditions of the region require rigorous testing that is beyond the scope of their products. 

DECRA, on the other hand, has had a long-established reputation for quality in Canada and our roofs have been enduring harsh Canadian winters for decades – still retaining their original beauty and strength. 

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Original article source: DECRA Metal Roofing