Owens Corning® FOAMULAR® NGX™ 250 Extruded Polystyrene (XPS) Insulation are closed-cell, moisture-resistant rigid foam boards well suited to meet the needs of a wide variety of building applications.1 Both products are great for above-and belowgrade residential and commercial applications such as perimeter/ foundation, cavity wall, precast concrete, under slab, and other applications.