The concept of pre-fabrication in the building industry is far from new, et both internationally and in Australia, the idea of using components which have been pre-assembled in factories or on manufacturing sites to build houses, commercial buildings and infrastructure has been gaining increasing traction in the latest decade.
In the US, for example, the 484,000 square foot 12-storey Miami Valley Hospital cardiac centre became the first major healthcare project in the US to have made extensive use of prefabricated components in design and construction upon its completion in 2010. Patient room toilets, casework and headwalls; integrated MEP racks about corridors; modular workstations for staff; unitised curtain wall sections and a temporary pedestrian footbridge were all built using components assembled off-site.
Indeed, a McGraw Hill Construction SmartMarket report in 2011 showed that in the US, 84 per cent of building contractors and 90 per cent of engineers report using some prefabrication, with 35 per cent of contractors saying doing so reduces average construction times by more than four weeks.
In Australia, meanwhile, Lend Lease last year used pre-fabricated cross-layered-timber to shave four months off the construction timeframe when building Forte, the world’s tallest timber building, in Melbourne.
Nowhere, however, has the push toward prefabrication been more evident than in China.
In late 2011, a local company known as Broad Sustainable Building (BSB) constructed the T30, a 30-storey building overlooking the Ziang River, in just 15 days. The quick construction time turned some heads - a YouTube video the company posted of the process went viral late last year. BSB is now planning to build the 838-metre high Sky City 1 skyscraper in the south-central city of Changsha in just 90 days. While that is a lofty goal, there is already considerable confusion and conflicting media reports over when the project is likely to start, as it has been delayed several times to date.
While cost and time frame considerations remain the key drivers of prefabricated building, proponents of prefabrication also say simpler construction associated with the technique means fewer mistakes and better quality outcomes, fewer materials on site leads to a safer workplace and the whole process minimises construction waste.
Still, there are drawbacks. Transport costs can be higher for prefabricated sections as opposed to individual materials, which can be packed more efficiently. The technique requires heavy cranes and precision handling to place in position, and large clusters of buildings made from similar types of prefabrication are not always visually appealing.
Finally, offshore manufacturing means fewer local employment opportunities compared with traditional on-site assembly construction methods – the latter point being particularly pertinent in Australia, where the Modular Fabrication in the Resources Sector in Western Australia published by Curtain Business School in 2011, for example, showed local steel fabricators faced costs 40 to 60 per cent higher compared with overseas competition.
Moreover, the Sky City project has its share of doubters. According to a report on designMENA, for example, Kevin Brass, public affairs manager and journal editor for the Council on Tall Buildings and Urban Habitat (CTBUH) says the idea for greater use of prefabrication in high-rise buildings is worth exploring but expresses concern the building might be potentially unstable as a lack of stiffness may cause the building to sway in the wind. Others are sceptical about the company’s ability to deliver such a project in such a short time frame, especially as pre-fab construction has never before been used to build a building of greater than 30 storeys.
Still, proponents say concerns about modular construction are overstated and based on ignorance. Janet Field, an account executive at US-based Triumph Modular, points out that modular buildings are constructed using the same quality materials as traditional construction, and that pre-fabricated modules are designed to meet requirements as per architectural specifications.
“Modular methodologies use an engineered approach to construction combined with technical innovation and lean manufacturing methods in a process that exemplifies the philosophies of ‘best practices,’” Field wrote on Triumph’s Design and Build Modular Blog last year. “Ongoing education within the construction industry is crucial to continued growth and increased market share for permanent modular construction.”