A rainscreen uses an exterior surface – a cladding layer – to break the force of sideways, wind-driven water movement. Behind the cladding is a weather-resistant barrier layer, working to repel any stray drops. The visible wall surface is ventilated to create a capillary break and to allow drainage and evaporation.
A rainscreen is an exterior wall detail where the visible wall surface stands off from the moisture-resistant surface of an air barrier applied to the sheathing to create a capillary break and to allow drainage and evaporation. The rainscreen is the siding itself but the term rainscreen implies a system of building.