They say first impressions count and undoubtedly, external wall and facades around the country are leaving lasting impressions on their visitors. But it doesn’t stop there.
The design of a façade has an immediate impact on the look and style of the building, along with its appeal and value. It plays a role in the environmental performance of a building and its longevity by protecting a project from the elements.
The trends and styles of exterior cladding in commercial projects are continually evolving in response to client demands and consumer perceptions. In the current environment, these are being shaped by aesthetics, the desire for green space and events, with the tragedy of London’s Grenfell Tower fire and issues with the Opal Tower, bringing fire safety and certification to the forefront of client and consumer concerns.
“From a holistic building risk perspective, the choice of cladding material on high-rise buildings is a critical issue and can, in some cases, be a dominant factor impacting health and life safety of occupants,” says Mark Tatam, Building Technology director, Kingspan Insulated Panels.
Choice of cladding and facades needs to be based on a careful evaluation of a product’s ability to stand up against the elements, while providing a durable, aesthetically pleasing appearance.
“The products chosen must meet the prescribed energy and acoustic performance ratings, they and must comply with current Australian Standards for combustibility, and there are waterproofing challenges that need to be addressed,” Ray Ferretti, national product manager at Big River Group says.
“Designers and builders must also consider the maintenance aspects of these products,” Ferretti says.
What are the options?
Aesthetics and fire safety have emerged as driving factors in commercial wall and façade trends.
In aesthetics, there’s the elegant look of brick veneer, the grand and industrial feel achieved with rustic weathered or lustrous metal cladding or panels and the contemporary and modernity of autoclaved aerated concrete (AAC) panels, says Geoffrey Ong, product manager, CSR Hebel.
There’s also the minimalistic, uncluttered option of stone panels, the industrial, creative look of pre-cast concrete, the “clean and sleek” appearance of FC panels, or the possibility of using multiple façade products to provide a more contemporary style.
“The desire for timber in external facades continues to be favourable, however due to ongoing maintenance and fire constraints, architects and designers have been looking for alternatives that offer a similar appeal, without the maintenance hassle,” Andrew Ritchie, architectural consultant, Atkar Group says.
“Popular alternatives such as timer-look aluminium claddings and battens look like real timber but are suitable in high rise situations,” Ritchie says.
Combatting fire concerns
Fire safety has become a prominent challenge for designers and certification bodies following the 2014 Docklands fire and 2017 Grenfell fire, with a new standard being introduced to combat concerns.
Standards Australia and the Australian Building Codes Board have developed a new Australian standard, AS5113. The standard is based on fire testing of large-scale facades to provide a more accurate indication of the fire combustibility of wall claddings and wall assemblies.
AS5113 is a façade test for validation of fire performance of external wall systems and is designed to provide reassurance that external cladding materials can be used with confidence.[1] When considering external wall or façade options, the first question is whether it is combustible, and the next is to check if it passes AS5113.
Fire safety in commercial buildings needs to be approached holistically. Dr Mark Tatam, building technology director, Kingspan Insulated Panels, said fire safety needs to incorporate management of fire load and ignition sources, restricting fire spread and finding ways that occupants can safely and quickly exit the building.
“The choice of cladding material on any high-rise building, whether for commercial or residential use, is a critical issue,” Tatum says.
“What we have found in recent times is that the external façade can create a dominating role in fire spread and with devastating consequences, especially when other fire safety systems are not designed to cope with such eventualities.”
Tatum says many building materials are designed to work as a system with other elements to fulfil the building code performance requirements in ways that create cost, design, construction and liveability advantages, whilst at the same time not stifling innovation in the building industry.
“Products that are fit for purpose, in meeting all required building regulations and are installed or used in their intended manner will reduce the spread of fire risk,” he says.
Fairview technical manager, Ashley How says while fire safety is a big issue, a potentially larger issue facing the cladding sector is “the rapid, and at times ‘knee jerk’ changes to regulation and compliance, making it difficult for parties to manage risk and compliance into the future”.
“Often ignored, the Shergold Weir report - a government commissioned investigation into broader compliance and enforcement problems within implementation of the NCC - identified a systemic breakdown of compliance and enforcement with the building code across the entire construction sector,” How says.
“Combustible cladding is really only a symptom of this greater issue, although it has typically been chosen as the scapegoat by the media.”
Structural concerns
The Opal Tower put the spotlight on structural certification after it gripped headlines when cracks in a 10th-floor precast concrete panel appeared and loud noises were reported on Christmas Eve in 2018. This triggered the evacuation of residents from the 392 apartments in the Sydney Olympic Park building. The final report indicated the building was “overall structurally sound” and uncovered multiple structural issues in the hob beam/panel assembly, grouting and construction and material deficiencies, raising questions regarding how the building was ever approved.
The incident highlighted ongoing industry issues and will see a greater emphasis on structural certification, says Kim Roughan, national marketing manager, CSR Cemintel.
Although the façade material is not a structural element of the wall, the incident does bring attention to the importance of a structural engineer, and ensuring decisions made after the initial design are properly checked and certified.
What about green walls and facades?
The “greening” of entire cities is a phenomenon that architects cannot afford to ignore. Many commercial buildings are opting for green walls and facades to create a desirable aesthetic and provide a visual demonstration of a company’s commitment to sustainability. Green walls and facades can offer thermal influence benefits by reducing the building’s temperature and air conditioning costs, lessening reflective light and heat and offering acoustic insulation.
“Some studies have reported that plants in and on buildings have improved task performance and mood states,” says Fraser Torpy, senior lecturer for School of Life Sciences, University of Technology, Sydney.
“Other studies have found that the plants could promote human creativity and increase the comfort and attractiveness of the built environment, while at the same time decreasing worker distractions.”
Although plants and greenery are often seen as fuel for fire, European studies have indicated vertical gardens and green walls can be quite fire safe, provided they are well-maintained. The fire risk can be significantly reduced through a working irrigation system, regular maintenance and keeping fire hazards such as electrical appliances and wires away from the wall. This is compounded by using low combustible materials through a fire-tested green wall or fire-safe materials. Soil can also help dampen the area, along with and opting for plants which hold water in their leaves.
Another key consideration is the weight loading of a green façade. The advice of a structural engineer will ensure a comprehensive design based on the building’s construction, condition and weight loading capacity. The building structure must be able to support the dead, live and transient load. It’s important to consider the weight of the plants at their maturity.
Read the full artcile in the April / July issue of Architecture & Design magazine.
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