It is the most popular fabric for waterproof structures usage, composed of polyester weave that is coated on both sides with PVC, in shot for poly vinyl chloride. PVC provides much needed weather protection for the shade sail. In order to gain flexibility, plasticizers are added in the mix making it easy to handle and install. The difference between PVC fabrics are considered trough weight and grades of tensile strength and tear strength. In addition, the top coats of acrylic and PVDF (polyvinyl-idene-fluoride) are used on fabric to help material to stay clean, though periodic cleaning may still be needed in some cases.PVC fabrics usually have a 10-15 year life span though some structures can last for 20 years.