Pressure equalization in rainscreen wall systems

Abstract

If the pressure in the air chamber behind the rainscreen is less than the pressure in front of it, rain is actually driven into the air chamber, which is, of course, undesirable. Through pressure equalization, this pressure difference is eliminated. A rainscreen wall has vent holes through which air can flow quickly to achieve pressure equalization. Two types of pressures -- static and dynamic -- have to be considered when calculating the size of the vent holes. Also, the pressure in an air chamber is not constant across the facade of a wall. That needs to be considered in their placement.