GreenGuard® GG25-LG XPS Insulation Board is comprised of closed-cell extruded polystyrene (XPS) with a minimum compressive strength. Produced with a blowing agent blend for GWP of less than 50. It has high water resistance & an R-value of 5.0 per inch of thickness. It retains its insulating properties over time. Use this insulation for below slab, cavity wall, and foundation applications.