Polymeric foam and polymeric foam products that contain a foamable polymer material, at least one blowing agent, a polystyrene/polyethylene oxide copolymer, and optionally, an infrared attenuating agent, are provided. In exemplary embodiments, the blowing agent includes at least one hydrofluorocarbon blowing agent. The maleic anhydride- styrene copolymer grafted with polyethylene oxide provides a water vapor permeability of 1.1 perm inch or greater in the extruded foam product without detrimentally affecting physical or thermal properties of the product. Additionally, the copolymer of maleic anhydride-styrene grafted with polyethylene oxide has a positive affect on the processability of the blowing agent(s) in the composition by both widening the process window and enhancing the solubility of the blowing agent in the polymer melt.; Thus, the polystyrene/polyethylene oxide copolymer present in the inventive composition acts as a cell enlarger, a plasticizer, and a processing aid. A method of forming an extruded foam product is also provided.