With its extruded polystyrene (XPS) closed-cell construction, this board has high water resistance making it ideal for use in moisture prone areas. An R-Value of 5.0 per inch of thickness makes it an excellent thermal insulator that increases the energy efficiency of your structures. And it retains its insulating properties over time. Produced with a blowing agent blend that has a GWP of less than 50. Choose between a square edge (CM) and an interlocking shiplap edge (SL). LG XPS Insulation Board is ideal for a variety of applications, including below slab, below grade along the foundation, inside basement walls, exterior insulation over wood sheathing, and residing.