Polymeric foam and polymeric foam products that contain a foamable polymer material, at least one blowing agent, an additive blend of polyethylene oxide and a copolymer of polystyrene and maleic anhydride, and optionally, an infrared attenuating agent, are provided. In exemplary embodiments, the polyethylene oxide is ethoxylated polyethylene oxide. Additionally, in at least one embodiment, the blowing agent includes at least one hydrofluorocarbon blowing agent. The blend of ethoxylated polyethylene oxide and copolymer of polystyrene and maleic anhydride provides a water vapor permeability of 1.1 perm inch or greater in the extruded foam product and increases the average cell size of the foam product without detrimentally affecting physical or thermal properties of the product.; Additionally, the additive acts as a cell enlarger, a water vapor permeability enhancer, a plasticizer, and a processing aid. A method of forming an extruded foam product is also provided.