This article was submitted by Jim Daniels, ATAS International Inc.
Understanding Rain Screen Wall Systems is published to clarify to the architectural and design community the key principles and background information employed in Drained / Back Ventilated or Pressure Equalized Rain Screen wall systems. It is also available as a resource to the General Contractor, Code Official or Owner communities to explain how the design properties of these two systems accomplish water infiltration management and prevention. Both systems employ some amount of open joinery and generally allow a certain amount of water into the cavity area between the outer and inner leafs. Drained / Back Ventilated (D/BV) systems rely on the ventilation cavity to both drain and dry-out the residual water. Pressure Equalized Rain Screen systems (PERS) also employ a ventilated and drainable cavity but add compartmentalization to limit water penetration in wall areas such as building corners where wind and wall cavity pressures can vary significantly. In these areas the compartmentalization of the wall cavity will facilitate rapid pressure equalization. PERS systems will greatly minimize and in some designs eliminate water penetration into the rain screen cavity. Rain screen wall systems may be designed as D/BV or PERS systems using a variety of cladding materials such as Metal Composite Materials (MCM) or single skin metal products.