rainscreens

Rainscreens refer to exterior cladding systems that create a ventilated cavity between the outer skin and the wall behind it. The design purpose is to manage precipitation and humidity by allowing water that penetrates the outer layer to drain and evaporate, reducing moisture transfer to the structural wall.

A typical rainscreen system comprises an outer cladding layer, an air cavity (often 20–60 mm wide), a drainage plane or weather-resistant barrier, and the backing wall or sheathing. A subframe or furring keeps the cladding off the wall and provides channels for air movement; weep holes and vents at the top and bottom facilitate drainage and ventilation.

How it works: the outer layer sheds most rainfall; the cavity provides space for water that enters to drain through weep holes and for air to circulate, promoting drying of the surface and behind-wall components. The weather-resistant barrier reduces water intrusion while allowing vapor to escape; the back of the system is typically insulated. This arrangement helps manage condensation and temperature-related moisture issues.

Variants and terms: ventilated rainscreens rely on continuous airflow in the cavity; pressure-equalized rainscreens use openings and air paths sized to minimize water entry under pressure fluctuations. Materials range from metal panels and fiber cement to timber, ceramic, and brick, enabling a variety of aesthetics.

Considerations: successful performance depends on detailing at edges, penetrations, and openings; maintenance includes clearing weep holes and ensuring seals. While rainscreens can reduce moisture-related problems and expand cladding options, they add design and construction complexity and cost.