A prefabricated roofing panel composite includes a prefabricated cover board having a high-density polymer or predominantly polymer material core layer having a density between 6 lbs/ft3 and 25 lbs/ft3 and an insulation board that has a low-density polymer or predominantly polymer material foam core layer having a density less than or equal to about 2 lbs/ft3. The cover board may have a waterproofing membrane forming the top major surface of the cover board. The low-density foam core layer of the insulation board may be formed with the high-density core layer of the cover board being currently or subsequently formed over and bonded to a top major surface of the low-density foam core layer in the same operation or preformed insulation boards may be fed into a production line with the high-density core layer of the cover board being formed over and bonded to top major surfaces of the low-density foam core layers of the insulation boards.