What is a Rain Screen?
Architects and designers seeking better moisture management and energy efficiency from the exteriors of their projects are turning to rain screens as a solution for both. A rain screen is an exterior cladding infrastructure that sits away from a building's outside wall's weather-resistant barrier, creating an air cavity directly behind the cladding that helps to protect the buildings important weather-resistant barrier. This allows any moisture that may pass by the cladding to easily drain away from the building, and the air that flows between the cladding and the wall accelerates evaporation of any residual moisture.
A rain screen should be viewed as a building envelope support mechanism, whose primary function is not to provide barrier protection against water penetration (such as a weather-resistant barrier does). Rather, a rain screen is designed to limit the amount of water that could potentially come into contact with the primary building envelope’s moisture barrier, thereby reducing the chance of water finding a way into the wall assembly. It does this by defending the wall assembly against the five forces that drive rain into buildings: kinetic energy, gravity, capillary action, surface tension and pressure gradients. (See animation that illustrates how a rain screen works.)
Knight Wall Systems’ rain screen solution is a unique system in that it not only creates an air cavity to help limit the amount of water contacting the building's primary envelope, but it also provides a solution for attaching nearly any type of cladding to a continuous layer of exterior rigid insulation. As a result, it dramatically increases the energy efficiency of the building, meeting the definition of continuous insulation set by ASHRAE standard 90.1.