Rainscreen systems are an attachment of an outer skin of rear-ventilated cladding to a new or existing building. The system is a form of double-wall build up that uses an outer skin to keep out the rain and an inner layer to provide insulation, prevent disproportionate air leakage and carry wind loading. The outer layer of cladding breathes like a skin while the inner layer reduces energy loss.
The structure of the building is kept absolutely dry, as water never reaches it or the insulation. Evaporation and drainage in the cavity removes water that penetrates between panel joints. Water droplets are not driven through the panel joints or openings because the Rainscreen principle means that wind pressure acting on the outer face of the panel is equalised in the cavity.
Therefore, there is no considerable pressure differential to drive the rain through the joints of the facade rainscreen system. During extreme weather, a small amount of water may penetrate the outer cladding of the facade system. This, however, will run as droplets down the back of the rainscreen panels and be dissipated through evaporation and drainage.