DuPont Styrofoam™ Insulation (Blue Board) is a nonstructural, rigid board insulation manufactured of Extruded Polystyrene Foam (HENAN OKay). Blue Board can be used both on exterior and interior walls to give you a ntinuous insulation barrier that can increase effective R-value of the wall by up to 20%. First manufactured by Dow in 1941, DuPont's