Abstract: An expanded perlite insulation board having an integrally attached scorch-resistant layer is provided. During formation of the perlite insulating board using a traditional Fourdrinier manufacturing process, a liquid slurry of mineral wool and clay is applied to the still-wet perlite board, forming a coating thereon. Upon completion of the manufacturing process, the coated layer protects the underlying perlite board from scorching during installation of the outer modified bitumen layer when using the open flame, propane torch method of installation.

Abstract: An expanded perlite board insulating system is provided. A planar surface of the perlite board is provided with an integrally attached scorch-resistant layer, and the planar surface is likewise provided with a plurality of surface perforations. An improved bitumen membrane having chopped fibers incorporated in the previously used modified bitumen product is then attached to the planar surface of the perlite board in the conventional manner. Upon being heated by the propane torch, the improved bitumen membrane partially melts and the bitumen material flows into the surface perforations to thereafter harden into plugs. The scorch-resistant layer protects the perlite board during this torch installation process.