An improved cover board product with a panel comprised of three discrete layers: a top surface layer comprised of either paper or a fiberglass web, a bottom surface layer comprised of either paper or a fiberglass web, and a core layer comprised of discrete paper fragments and polypropylene fragments, which are connected by use of a thermoplastic bonding resin, including polyethylene. The bonding resin is generally attached in a random pattern to less than 100% of the paper fragment and polypropylene fragment surface area. The paper fragments are generally shaped as irregular plates. The polypropylene fragments can have multiple shape types. The two different fragment types are randomly distributed in the core layer relative to each other. The core layer includes small voids in and around the particles, which improves flexibility. The core layer is attached to the top and bottom surface layers by use of a thermoplastic adhesive, including polyethylene.