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With most shade sails employing HDPE fabrics with a 10-year UV warranty, properly engineered and constructed structures are designed to withstand the hot sun. But what about other elements, such as snow loads or strong winds? According to Ashley Donde, vice president of sales for USA SHADE & Fabric Structures, shade sails need to be engineered to the minimum building code requirements, which in the United States is the IBC 2007. The minimum requirement for a live load is 10 pounds per square foot—an important consideration when shade sails are installed in snowy climates. “Shade sails can be designed and engineered to support snow loads in certain areas,” Donde notes. “Some sail structures are engineered up to 60 pounds per square foot.”
“An engineer may add auxiliary members, such as additional cables or steel supports, to help the fabric or increase the slopes so that they won’t accumulate so much snow,” adds Tiffany Sands of Killer Shade. “But one of the downsides of installing a shade sail anywhere there is snow load is that if the snow does accumulate, the fabric could stretch. Come summertime, the heat will help it to re-tension, but there is no guarantee that it will do so back to its original position.” In these instances, Killer Shade has helped customers design the structure specifically to make it easy to remove in the winter and reinstall in the spring.
When it comes to wind, most shade sails are fabricated to withstand a minimum of 85 mph, three-second gusts. USA SHADE, for one, engineers its structures up to 150 mph, dependent upon the location of the structure. “You have to design sails to zero-wind pass-through,” Donde explains. “The HDPE fabric reaches its maximum density at approximately 45 mph. At that point, no more wind can pass through the fabric, and it acts as a solid fabric. If it’s not engineered correctly, the structure could fail.”