A common feature in curtain wall technology, the rainscreen principle theorizes that equilibrium of air pressure between the outside and inside of the "rainscreen" prevents water penetration into the building itself. For example the glass is captured between an inner and an outer gasket in a space called the glazing rebate. The glazing rebate is ventilated to the exterior so that the pressure on the inner and outer sides of the exterior gasket is the same. When the pressure is equal across this gasket water cannot be drawn through joints or defects
A rainscreen is the exterior weather-facing surface of an exterior wall detail that stands off from the moisture-resistant surface of the structural backup wall. The rainscreen is the first interruption between conditions that exist on the outside of a walled building and conditions that are required on the inside of a walled building.
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