Today, more than before, exterior wall cladding has become a necessity. The cladding systems and materials are meant to serve the aesthetic aspect and be functionally sustainable and easy to maintain. While creating functional designs, today's building facades should provide the architects with the freedom to explore their creativity without constraints. It should allow them to make perforations, flex the materials without impacting the strength and structural stability.
Stone cladding, wood and glass cladding panels, metal panels/ Aluminium Composite Panels (ACP) have been popular traditionally. However, innovative materials that are high on quality and safety clubbed with the aesthetic appeal are rapidly gaining ground. Some of the other new-age cladding materials include Glass fibre reinforced concrete, carbon fibre, Ultra High Performing Concrete (UPHC), metal cladding (zinc, copper & steel), terracotta, ceramic, wood composite material, High-Pressure Laminates (HPL), slim porcelain slabs, exterior grade laminates, fibre reinforced plastic, carbon fibre, Corten steel, ETFE membranes and solid surfaces etc.
Newer technologies, materials, energy efficiency norms and environmental considerations are fast replacing the conventional cladding methods and solutions.
The rear ventilated facade system is a modern and one of the highly advanced cladding systems. In addition to its functional safety, it provides architects with design possibilities. This system maintains a gap between the building envelope and cladding and between cladding elements to ensure sufficient airflow behind the cladding.
The rear ventilated cladding system also acts asrain screen claddingwhich protects the building during monsoons by draining rainwater away from the wall.
The double skin facade has increasingly become popular in the last two decades due to its contribution to energy consumption and sustainable development. This external wall cladding system consists of two skins placed in such a way that the air flows in the intermediate cavity. The cavity between the two skins may be ventilated either naturally or mechanically.
Well-designed sun control and shading devices can phenomenally bring down building peak heat gain and cooling requirements. In addition, they can drastically enhance the natural lighting quality of building interiors. As a result, it has become an essential aspect of energy-efficient design strategies. Tinted electrochromic glass is one such new-age material that can benefit as a glazed faade without using blinds that can block the external view and daylight ingress.
With the recent updates in the National Building Code of India, fire rating of faade systems is given the importance. The external cladding system for fire resistance uses cladding materials like exterior grade laminates that can retard fire material and stop its propagation. Planks or weatherboards made from fibre cement or steel, concrete, Greenguard certified HPL panels for green buildings, PVC or aluminium, sheets and panel materials, double hardened resin and reconstituted timber products are few other fire-retardant cladding materials.
For the earthquake-resistant cladding system, just like lightweight roofing, the materials should be lighter to make the structure resistant to lateral loads and reduce the load on the building and its foundation. Fibre cement, PVC or aluminium are few useful products. While choosing the materials, it is essential to prioritize the geographical vulnerabilities. For seismic zones, brittle or stiff cladding materials should be avoided. As a case in point - Although concrete is an excellent fire-retardant, it is not a stable material for earthquake-prone areas. For such places, steel-reinforced concrete is a preferred option.
In India, structures above 15 meters in height qualify as a tall building. As per Indian Green Building Council (IGBC), commercial buildings consume more energy than highways and roads. Moreover, High-rise buildings are constantly exposed to climatic extremities. Cladding in such buildings involves detailed structural designs and calculations for wind load requirement and high impact resistance. There are physical challenges such as scaffolding limitation, accessibility and logistics of construction materials and increased risk of fire.
Specific grades of concrete like M25, M30 or M40, specific grades of reinforced steel bars are some of the materials that can be used for constructing tall structures. Having anti-graffiti properties like Exterior Clad Laminated (ECL) high-pressure laminates, and porcelain wall cladding is essential as the smog & silica particles in the air may cause visual defects. The ultra-thin, large format porcelain slabs are doing rounds in the current times. These slabs, which are 3 mm in thickness, are lightweight and ideal for tall structures.
Genuine Compact Laminates can be customized for each building for different wind loads, dead loads, thermal loads and other requirements and protect the building from extreme climates.
Curtain glazing is a flexible cladding solution with glass as its primary material. The curtain glazing is designed to withstand wind and earthquake loads, air leakage, and excessive heat loss. Installation of DGU (Double Glazed Unit) is preferred as it provides effective insulation against heat loss and enhances energy efficiency and aesthetics.
A double-skin faade helps to reduce the pressure differences in a building in the faade cavity. Since most commercial buildings have glazing, optimizing excess heat & light coming into the building is crucial. The double-skin facade could be a future system of coexistence and placement of two skins so that air flows in the intermediate cavity.
For sustainable development, choosing intelligent facade systems, smarter materials, optimizing design and layout and reducing long-term costs is imperative. Sustainability is not only a necessity but the only way of futuristically designing eco-friendly building faade systems.