A low noise roof deck system eliminates the thermal expansion noises associated with metal decking and includes structural features that permit installation of composite roofing shingles directly over the deck without venting. The system includes a composite panel base layer surmounted by a layer of water resistant material, a layer of foam synthetic resin insulation and a layer of mineral board. A second layer of mineral board may be overlaid on the first mineral board layer. The system is easily installed over a system of conventional underlying supports to provide a strong, rigid deck for supporting a waterproof composite shingle roof membrane and forming a quiet weatherproof roof system. The composite base panel has a layer of synthetic resin foam insulation sandwiched between a base layer of wood fibers bonded with an inorganic cement and an upper layer of a resin bonded wood product.