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Ventilated Façades
Rainscreen cladding is the attachment of an outer skin of rear-ventilated cladding to a new or existing building. The system is a form of double wall construction that uses an outer layer to keep out the rain and an inner layer to provide thermal insulation, prevent excessive air leakage and carry wind loading. The outer layer breaths like a skin while the inner layer reduces energy losses. The structural frame of the building is kept absolutely dry, as water never reaches it or the thermal insulation.
Evaporation and drainage in the cavity removes water that penetrates between panel joints. Water droplets are not driven through the panel joints or openings because the rainscreen principle means that wind pressure acting on the outer face of the panel is equalised in the cavity. Therefore, there is no significant pressure differential to drive the rain through joints. During extreme weather, a minimal amount of water may penetrate the outer cladding. This, however, will run as droplets down the back of the cladding sheets and be dissipated through evaporation and drainages.
Advantages
By insulating the structural wall externally the following benefits are achieved:
- thermal bridging is eliminated because there are no interruptions caused by floor slabs
- temperature fluctuations are minimised due to insulation on the outside
- interstitial condensation is prevented as vapour pressure and wall temperature restricts condensation to the ventilated cavity
- heat from the sun is dissipated so that the temperature is dispersed in the cavity and ventilated through openings
Ventilated Façade (Rainscreen)
rainscreen is a new building solution with a growing importance in modern architecture, not only for technical features, but also for it's aesthetic appearance. This ventilated facade system relies upon the fixing of terracotta or ceramic tiles on an aluminium substructure, previously fixed to the construction facade. The horizontal joints between tiles are left open to the cavity area of the cladding zone allowing for ventilation. rainscreen is fast to assemble and requires no wet trades, in comparison to traditional construction.
The principle behind rainscreen
The variation in air density between external and internal temperatures induce a funnel effect, giving rise to a consistent, upward airflow within the cavity. This continuous flow of air offers several, distinct advantages;
The key to achieving a continuous airflow within the cavity is consistent and accurate dimensions, which is extremely difficult using traditional wet trade forms of constructing building façades. A rainscreen system is an open joint cladding system, designed around the principles of air behaviour within the cavity. Past experience has shown that the airflow within the ventilation cavity in an open joint system is more consistent and beneficial than in a closed joint system, even under the effects of wind pressure or suction and during heating or cooling of the air.
Modern Day Application
The ventilated façades solution combines both the mechanical properties of extruding terracotta or ceramic and the aesthetic benefits of cladding material. An increasingly larger number of architects use this technique not only in refurbishment, renovation and conservation projects but also in new constructions where rainscreen provides unpaired aesthetic benefits, design flexibility and production of practically any shape and form.
Ventilated façades is a modern construction solution for new buildings and refurbishment projects. The system is targeted for schemes that need a secure, aesthetically pleasing wall cladding solution that can be applied to all types of buildings, including;
- Residential
- Offices
- Shopping Centres
- Hospitals
- Industrial
Rainscreen is an extruding terracotta and ceramic product using a mixture of natural clays, manufactured to the exacting standards of the 21st Century. This provides a unique range of standard and bespoke terracotta recurs and glazed finishes available in large, medium and small format sizes, making it the perfect façades solution for modern architecture.
Advantages of rainscreen
Thermal Insulation
In summer, the ventilated cladding provides the building with a natural thermal shield, which protects against heat gain from direct solar radiation. The constant ventilation keeps an ambient temperature within the cavity on the external side of the insulating panel.
A ventilated façades has the additional benefit of providing the walls of the building with a high thermal inertia, which is the ability of the wall material to conduct and store heat and make optimum use of both cold and warm climates. In summer, this results in the form of a retarded heat wave, so that solar heat stored inside the external wall travels slower. This means that during the day, heat will penetrate through the internal walls at a reduced rate, giving cooler internal temperatures. At night time however, when ambient temperatures are lower, the rooms are gently warmed by the stored heat.
In winter, the opposite effect occurs when heat within the building is stored for longer and the length of the external walls cooling time is increased. The final result is a more even temperature range, adding comfort and wellness inside the building where a type of a permanent micro climate is produced.
Energy saving
The energy balances calculated for buildings with ventilated façades suggest they can reduce the power consumption by up to 25% when compared with traditional buildings without thermal insulation.
This also translates into a considerable increase when calculated over the typical 60 year life of a building. The thermal benefits of ventilated walls clearly reflect the economical benefits of lifetime heating when compared with traditional construction.
Acoustic insulation
Rainscreen helps reduce sound transmission, providing an acoustic insulation at no extra cost. In fact, curtain walling increases the acoustic absorption properties of the original wall by up to 6 dB, equal to a 50% reduction of the noise level within the building.
Moisture prevention
The natural circulation of airflow within the cavity helps to evaporate any moisture present due to either condensation or capillary action.
Weather protection
A ventilated façades provides a perfect long-term protection for the building against wind driven rain water and weathering agents, such as rain, ice and snow. These are one of the main causes behind exterior deterioration of any construction. Research shows that no significant rain or snow infiltration occurs into the cavity on ventilated façadess fixed to the building by means of open-joint technique, even if exposed to a strong wind pressure.
Rainscreen also provides protection against meteoric water, an important feature in terms of reducing the frequency of maintenance cycles, adding life and extended durability to the building.
