A vent screen installed at the bottom of an HPL rains screen wall should have at least 2.34 square inches per linear foot (42.32 square centimeter per linear meter) of free open area. This minimum open-free area should also be continuous behind the panels. A minimum of 1/4" gap should also be kept at the top of the wall between the trim or the metal flashing and the edge of the panel to allow the air from the cavity to evacuate.
