Press Information
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| Issued: March 2008 |
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Au Naturel
Although the primary function of a rainscreen is to protect the inner leaf of a building from wind driven rain and ultra violet light, architects are increasingly using this type of cladding to push the boundaries of exterior envelope design. With natural finishes such as terracotta and stone proving most popular, façade innovators have responded with advances in system technology that help bring down the cost of these traditionally premium materials. William Harwood, T.I. Dynamic Facades, explains how this has been possible, and why rainscreen cladding will continue to rise in popularity.
As with all types of cladding system, rainscreens offer a practical build choice. A simple and efficient installation procedure helps to minimise site programmes and reduces the number of trades required to complete the wall construction.
Natural materials such as terracotta and stone have long been favoured at specification level because they lend themselves to clean and stylish design. Thanks to intelligent engineering, these natural finishes are also now a favourite with contractors, because they deliver on all counts – aesthetics, affordability and practicality.
The next generation
New terracotta systems are emerging which make them a popular choice for all types of development. Historically, twin skin tiles have been necessary to deliver the required impact performance. However, new systems launched to market are removing the need to use a twin skin design because technological advances have made the lighter weight single skin tile a viable option.
Increased strength and durability is achieved through an innovative manufacturing process. A porcelain base baked at a high temperature significantly reduces the water absorbency of the system, making it more resistant to the freeze/thaw phenomenon that causes some silicon sprayed alternatives to fail.
The precision calculated vertical carrier systems of these modern terracotta systems offer complete design versatility as well as fast installation. To accommodate the full range of design requirements, they are available in module sizes ranging from small, typically 150mm x 400mm, to very large at 300mm x 1,200mm.
Large format panels deliver the clean finish demanded by many premium developments, and remain easy to install owing to the sophisticated carrier system and minimal weight of the tile. At the same time, smaller tiles provide a cost effective solution for breaking up the monotony of a lower end finish, such as render. This is because the vertical carrier system will easily integrate with the primary frame of most alternative exterior finishes.
A lighter choice
To withstand aggressive environmental conditions and deliver the required performance, stone façades have traditionally had to be approximately 40mm thick. The consequence of this is that the system generally takes longer to install, resulting in increased labour costs.
To help make stone more competitive, façade innovators have developed lighter weight systems that are durable and easier to install than conventional constructions. Where stone is concerned, this has been achieved by creating a facing that is reinforced with a high strength fibre, aluminium or aluminium honeycomb backing. Stone facings are manufactured 6mm to 15mm thick and bonded to one of the backing systems, with the type of backing determined by the specification requirements of a project.
Sandstone, limestone, granite, basalt and marble can all be manufactured in this way to achieve a durable, high performance finish, without the need for a stonemason. While this offers an on-site cost saving because it substantially reduces site programmes, it also brings the overall system cost down because less of the raw material is required per square metre.
Continual innovation
In addition to these more traditional, natural façade materials, innovative urban glass systems have also been developed and are already proving as popular as natural products.
These high performance systems are available in high gloss or honed finishes to create a silk or matte look, which is extremely durable and impervious to staining. These systems are very versatile and, in addition to various panel sizes, they can be shaped and curved to clad pillars and create rounded corners.
Continual innovation, both in terms of cost engineering and high quality finishes, has raised the profile of rainscreens and made the systems a popular construction as well as design choice. This trend is expected to continue, as the façade industry drives forward increasingly inspiring yet practical system developments.
