Made of various metal materials — such as tin, aluminum, copper, and galvanized steel — metal roofs are known to withstand some of Mother Nature’s most wicked rages. Be it heavy rainstorms, hailstorms, and snow, a metal roof will keep homeowners safe and away from all kinds of windblown debris and natural elements. In addition to being fire-resistant and impervious to the most unforgiving weather and troublesome pests, metal roofs are also an environmentally-friendly roofing solution for their unmatched longevity, superior energy saving features, and high recyclability.

Longevity

According to the Metal Roofing Alliance, the typical service life of a metal roof is two to three times longer than that of asphalt shingles. As Building Owners and Managers Association (BOMA) research finds, metal roofs have a significantly longer expected service life than all other roofing materials. Metal roofs are malleable and can be pressed and shaped without suffering any break or crack. Lasting considerably longer than the average 15- to 23-year service life of asphalt shingles, a metal roof can last up to 60 years and beyond. Combined with its minimal upkeep, it is no wonder that homeowners love metal roofs for their generous financial savings in roofing repair and replacement. Though initial upfront costs are higher than asphalt options.

Energy Efficiency

Using a solar spectrum reflectometer and an emission meter to conduct their three-year-study on the energy efficiency and service life of metal roofing systems, Oak Ridge National Laboratory’s Buildings Technology Center found the high solar reflectivity and emissivity levels of cool metal roofing can greatly mitigate urban heat island effects. Moreover, while white coatings on other roofing materials displayed a 25%-40% drop in their initial reflectance, metal roofing retained most of its initial solar reflectance during the three-year study. In fact, the researchers found that pre-painted metal was able to keep almost 95% of its reflexivity.

Another study showed that an unpainted metal roof demonstrates a very high solar reflectance level that usually exceeds the minimum federal EnergyStar requirement of 60%. Depending on the color of a painted metal roof, the reflectance range can go anywhere from 10% to 75%, which is definitely better than the 5% to 25% range of an asphalt roof. As a recent case study on the trend of cool metal roofing in North America points out, dark colors can absorb significantly more solar radiation than light ones. Therefore, switching to a white- or light-colored metal roof will not only reduce energy spending by 20%, but also make your home 50 to 60 degrees cooler than a conventional dark-colored roof.

Recyclability

Finally, the unmatched recyclability of metal roofs makes them a favorite of many “green” enthusiasts. According to research conducted by the Florida Department of Environmental Protection (DEP), metal roofing is the most eco-friendly roofing solution. Many metal roofs contain up to 40% recycled steels, while the content of metal roofs in itself is 100% recyclable. As a result of its high recyclability and reusability, most metal roof materials rarely become waste in a landfill. When compared to Environmental Protection Agency’s (EPA) estimation of 11 million tons of asphalt shingles ending up in landfill, it is clear why those in the government agency and home improvement industry are calling metal roofing an eco-friendly solution for every homeowner.

 

Standing seam metal roofs come in sheets up to or sometimes more than 30 feet (9.1 m) long and widths of 12, 14, 16 or 18 inches (300, 360, 410 or 460 mm). The standing seam is typically 1+1⁄2 or 1+3⁄4 inches (38 or 44 mm). They are more expensive upfront for installation and material costs but last longer than asphalt shingles, over a lifespan of at least 50 years, they are less expensive than asphalt shingle roofs. They require less maintenance than corrugated metal roofs because of the exposed fasteners on that roof.

Mechanically seamed roofs are seamed together using a roof seamerand can be either single lock or double lock seamed, meaning they can be folded under once to be seamed together or folded under twice for extra weather protection. This is the most expensive of the three types but is the most weather resistant.

 

Single Lock or Double Lock?

Mechanical standing seam profiles are most commonly seen looking like the profile below

 

 

Notice that the edges are formed into male and female profiles. These male and female profiles are designed to nest into one another and then are seamed using a crimping tool. A single lock seam, as pictured below, stands up and bent at 90° when locked together (upside down “L”). The single lock seam is suitable for mild climates with less wind and precipitation. One advantage single lock seams have is that they are more easily pulled apart for repair if the roof is damaged.

 

 

 

 

More often than not, mechanical seams are folded once again into double lock seams. There are many advantages of double locking your seams.

 

• Low slope or steep slope applications: 2/12 minimum ; even .5/12 is some cases when continuous in-seam sealant is applied
• Weather Tough: The double lock system is ideal for extreme weather conditions and resists strong winds and heavy wind-driven rain. 
• Historically accurate: Mech. lock is generally regarded as aesthetically appealing. You will commonly see 1” mechanical seams in copper.  The double lock system has been used for centuries around the world and has stood the test of time. The slim profile of the seam is visually appealing for residential applications
• Versatility: Mechanical seams do not need to rely heavily on “Z” closures and sealant. There are a variety of European folding details that give the roofer skilled options to show off their abilities and create value for their customers.

 

 

source:

https://breakingenergy.com/2014/08/06/top-environmental-benefits-of-metal-roofing/

https://www.stortz.com/why-choose-mechanical-lock-standing-seam/?srsltid=AfmBOooU-2l3zcgwTgt2_-uowjR7KMSLp9MZkB94hV4KWtZUMKHfyGzq