BP ESGARD 1/2" High Density Roof Insulator or High Strength Roof Insulator are composed of interlocking wood fibers impregnated with a water-repellent petroleum wax emulsion that imparts a high resistance to water absorption. BP ESGARD 1/2" High Strength Roof Insulator and BP ESGARD 1/2" High Density Roof Insulator have very good insulation properties. Both the products increase the strength and rigidity of the roof system. They have an ideal surface for the application of hot asphalt and they provide an excellent substrate for the roofing membranes.