A method for molding composite structures whereby a material stack including a core having first and second opposing sides is prepared. The preparing of the material stack includes applying a fibrous support layer on at least one of the first side and the second side of the core section, applying an adhesive layer on the support layer, and applying a thermoplastic barrier layer on the adhesive layer. The method also includes preparing a resin and a mold; placing the material stack in the mold; sealing the core; infusing the mold and material stack with resin; curing the structure; and removing the structure from the mold. In one embodiment, the method creates a composite aircraft wing panel.