HeatlokSoy is a rigid foam insulation that expands as it dries to fill the space in which air can circulate or moisture can condense, sealing cracks, gaps and voids and creating a more energy efficient environment. This closed-cell, rigid polyurethane spray foam insulation formula contains more than 20 percent recycled plastic materials and soy. It exceeds government performance standards for air barrier materials by as much as 500 times, according to the manufacturer.