GreenGuard Type IV 25 psi Insulation Board is an ideal exterior insulation, meeting your needs for multiple applications. Its extruded polystyrene (XPS) construction provides superior moisture resistance. And since it does not absorb moisture, it retains its insulating properties over time. With an R-Value of 5.0 per inch of thickness, the board increases the energy efficiency of your structures. Plus it's lightweight, easy to handle, and easy to cut with a knife. Use this insulation for below slab, cavity wall, and foundation applications.