A rainscreen is a thin panel which is part of a double-wall construction that can be used to form the exterior of a building. The purpose of a rainscreen is to prevent large amounts of water from penetrating the wall.

There are two types of rainscreens;

• Drained and Ventilated rainscreen cladding systems allow any penetrating moisture to drain and vent to the outside.
• Pressure-equalised rainscreen cladding system allows the movement of air between the inside and outside of the rainscreen. Water is not driven or sucked through the joints as the pressure is equalled across the screen.

A rainscreen can be made out of many materials. A metal sheet made from aluminium, stainless steel, zinc and copper is fabricated. It can also be formed from composite materials, consisting of two skins of metal bonded to a lightweight core such as polyethylene. Other materials such as brick slips, stone and timber can also be used.

A common rainscreen system is made by Sto. It is called the StoVentec R system and is fixed to the exterior of a property with an aluminium sub-construction, creating a cavity between the façade and the render carrier board. This is part-filled with mineral fibre insulation for effective external wall insulation (or EWI).

The role of the system is to protect the wall by keeping it dry while also allowing it to breathe. This system is ventilated meaning there is no limit to the lightness value of the render system.