Wall Cladding Systems

Wall Cladding utilizing Rainscreen Systems are based upon two separate and distinct barriers on the exterior wall. The outer barrier sheds and controls (but does not eliminate) the majority of the rainwater through hydrokinetics, while the inner barrier performs the multiple functions of a final moisture and air/vapor barrier. The outer barrier allows penetration of water through open joinery. The volume of penetrating water will vary dependent upon design principle. This is where the Drained and Back Vented and Pressure Equalized Rainscreen approaches become separate and distinct design concepts that should not be combined. Both use the principle of controlling water leakage, but not necessarily stopping water penetration through the exposed outer barrier. The inner barrier design is treated differently based upon the chosen approach. Unfortunately, the term ‘Rainscreen’ has been generalized and consolidated into one commingled product in specifications combining both systems characteristics. To complicate and confuse matters, the air and water resistance criteria from the traditional single-line barrier systems have been applied to the design and specification of the exposed outer barrier. Placing air and water tightness criteria on the outer barrier contradicts the underlying fundamentals of the Rainscreen Principle. Both approaches can work successfully, but care must be taken that the two are not confused, since the adoption of hybrid versions can result in unsatisfactory performance.