Research has shown that exterior cladding materials on an exterior wall can prevent most, but not all, moisture from entering into a wall. Having a backup control system behind the cladding to control moisture by shedding it to the exterior is important for the long term durability of an exterior wall. A significant component of the backup moisture control system is often called by building envelope designers a drainage plane or a water resistive barrier (WRB). See how Spray Foam Insulation can act as a WRB and help control moisure in wall applications.