The Korax Rainscreen Stucco Panel is made of polystyrene board with vertical and horizontal grooves in the back that create a cavity. The panel is easily attached by mechanical fasteners to the wall. The vertical channels in the panel create cavaties 10 mm deep and 60 mm wide that lead water to flashing and weep holes at the bottom and vent holes at the top of the wall section also allowing air circulation. The vertical ribs are interrupted by horizontal channels, creating nodes that slope back towards the panel, providing positive drainage away from the building.