Rainscreen Systems

What is a Rainscreen?

Rainscreen System ExampleThese systems are designed on the principle that water will not move on its own. Rain and snow, the chief forms of water that impinge on a wall during normal conditions, are either moved downward by gravity, or sideways by wind. A rainscreen uses an exterior surface–a rainscreen cladding layer–to break the force of sideways, wind-driven water movement, so that any water that gets through the small breaches in the surface has lost its momentum. Most water simply bounces off the surface or runs down the exterior.

Any water that gets through the outer cladding layer is no longer being driven by wind, and is now only seeping. The cladding material is separated from the rest of the wall assembly by a small gap. When the seeping water reaches the inner surface of the cladding, gravity takes over and the water runs down the inner side of the cladding, never touching the rest of the wall. Behind the cladding is a weather-resistant barrier layer, working to repel any stray drops.  Because this barrier is behind the cladding, it’s protected from the deteriorating effects of the sun and has better durability and longevity.

For a rainscreen system to work effectively there must be enough space for water to run down the backside of the cladding – at least 1/8”. Additionally, there must be a place at the bottom of the wall for water to exit to the exterior. Drainage is absolutely crucial. This is why stucco walls have drip-edge at the bottom, and brick walls have weep-holes at the bottom. The weatherproof barrier must be well sealed, including seals around any penetrations such as fasteners that attach the rainscreen cladding.

Some rainscreen cladding systems are installed with an “escape” at the top of the cladding, as well. If the gap behind the cladding is open at both bottom and top, it allows airflow that helps dry out the backside of the cladding more quickly after a weather event.

For additional information regarding "Understanding Rainscreen Wall Systems", click here

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