For more than 50 years, Dow Building & Construction has been the recognized leader in extruded polystyrene insulation. Today, Dow Building & Construction offers an extensive line of science-based building envelope solutions, including: STYROFOAM extruded polystyrene Insulation, Dow polyisocyanurate insulation including, toprated THERMAX and TUFF-R also STYROFOAM WEATHERMATE housewraps.