Willseal® PF100 is a pre-compressed, self-expanding foam joint seal, engineered to perform as a weathertight primary seal designed for use in various prefabricated applications. It self-expands to fill the joint and is capable of +/- 50% movement from the mean joint size. The high-density polyurethane foam is impregnated with a modified flame retardant, UV stable acrylic resin and an integral silicone seal barrier, which is protected by the foam core. This revolutionary solution has been tested and validated to enhance building envelope connectivity, while also reducing the need to conduct installation activities from the exterior of the structure as panels are erected.