What is a rainscreen cladding system?
7th October 2017
Rainscreen cladding has been used for centuries to protect buildings from the elements. These rainscreen systems first became widely used in the UK during the 1950s because it provided an efficient and cost effective method of rebuilding much of the country’s infrastructure. Although still widely used for new build developments, re-cladding or overcladding is now commonly specified for refurbishment of existing buildings.
Rainscreen cladding systems provide new and old buildings with a number of performance benefits. Principally, rainscreen cladding works by creating a rear ventilated cavity between the reverse of the cladding panel and the outer face of the building. This enables air to constantly circulate, forcing any moisture that penetrates the joints of the cladding panels out, before it reaches the building structure.
That is important because damp, wet or saturated walls lose more heat energy and so preventing this with a rainscreen cladding system forms part of improving the overall energy performance and comfort of the building. Constant wetting and drying of walls can also result in rapid deterioration of the building fabric, such as spalling and flaking of masonry, and so incorporating a rainscreen cladding system into the new design or refurbishment makes sense for many reasons.
We can see, therefore, that the principle of rainscreen cladding is that the majority of the rain is stopped at the outer face of the cladding panel. Any small amount of rain that penetrates between the cladding panel joints is carried away by the ventilation in the cavity, or drains out at the bottom of the cladding, before it reaches building.
Rainscreen cladding provides another important role in our architectural landscape and that is its ability to transform the aesthetics of both new and old buildings. Indeed, over cladding an existing building can make it indistinguishable to a new build, and without the cost, disruption or much higher carbon footprint of demolition and rebuilding.
Rainscreen cladding is usually supported by an aluminium framing system that is located within the cavity and anchored back to the structure with brackets and primary fixings. This frame is integral to creating the rear ventilated cavity, with a variety of structural options and bespoke sized brackets available. These can be adapted to the building lines and can be developed to a particular design while creating the cavity offset required. It is recommended that this cavity offset is a minimum to create the ventilated cavity. This is not less than 38mm to ensure adequate air flow for drainage and ventilation.
Condensation within a rainscreen cladding system is managed by installing vapour permeable insulation and fabric membrane, which allows the building to breathe. Any moisture in the form of condensation that is expelled from the building due to its thermal mass, passes into the ventilated cavity and is expelled out of the building
Although we’ve focused predominantly on; what is a rainscreen cladding system?, we shouldn’t overlook the fact that introduction of modern cladding materials and finishes such as back painted glass, ceramics, and a plethora of metal finishes including patinated copper alloys, coloured stainless steels and dyed Zinc’s mean that architects now have more choice than ever when it comes to creating a building that stands out from the ordinary.
Combined with its building performance benefits, modern rainscreen cladding systems provide the flexibility of design, including minimal weight loadings, to create developments where people aspire to live and work. The fact that the rear ventilated cavity is protecting the building and its contents from the elements is one of the reasons why these cladding systems are now used on both old and new buildings.