Abstract: An improved system is disclosed drying interior layers of sheathing by reducing moisture in narrow wall spaces, particularly between layers of sheathing and/or insulation board. The method involves inserting a special nozzle into a hole drilled into the wall. The nozzle has a depth gauge in the form of a shoulder, calibrated screw threads or other equivalent means to control the placement of a drying substance into the space without damaging the insulation board or blocking the outlet for the drying substance which may be warm, low humidity air.