MUMBAI: Large construction project developers have been making a determined shift to using prefabricated structures since the pandemic-related lockdown, which made movement of labour and material harder.
Conversations with project consultants and construction firms on large EPC projects have shown that using such structures has kept work going at an even clip despite workforce falling by nearly a half.
Prefabricated structures are constructed by manufacturing whole building components, including beams, slabs, columns and walls, and transporting these to the site final where they are assembled, very much like putting lego blocks together. As the bulk of the work is done at an offsite location, it increases construction speed, ensures consistent quality and reduces wastage. While prefabs have been typically used so far in large scale affordable housing projects or where on-site construction is difficult, such as to build an offshore oil rig, their use is now being expanding to other areas such as metros, roads and highways and other public infrastructure.
Prefab structures have helped build new hospitals and quarantine facilities in record time through the covid-19 pandemic. Tata Projects, for instance, is building a 400-bed medical facility at Kasargod, Kerala, with prefabricated structures manufactured in Jamshedpur, Jharkhand, and then transported to Kerala by truck.
"One of the recent developments across the infrastructure and construction industry is increasing usage of prefab technologies for putting-up faster, high quality and cost efficient structures," K Satyanarayana, COO – Industrial Systems, Tata Projects Ltd, told Mint. "Unlink traditional technologies which depend heavily on on-site construction – prefab structures are delivered as a complete finished product from manufacturing facilities to the project site. It involves structural steel framework attached with factory finished cladding and roofing component."
This is also faster than traditional construction because different functions can be performed simultaneously. "For example, in conventional construction – the walls cannot be set until floors are in position, and ceilings and rafters cannot be added until walls are erected. But the advantage of offsite manufacturing facility production allows walls, floors, ceilings and rafters to all be built at the same time and thereafter be brought to site for assembly," Satyanarayana said.
“Pre-cast construction is less labour-intensive and ensures better quality but there is threshold size of project beyond which only it economic sense," Pankaj Vatsa, executive director at engineering consulting firm Egis India said. “Simply put, the capital expenditure cost of setting up a prefab unit is high. Wherever there is large requirement and there is standardization of construction elements and size, prefab is best option, like in mass affordable housing projects, metro rail elevated corridor etc."
“We use prefabricated girders for projects like elevated metro corridors or bridges," a senior executive at a construction company told Mint. “We need workers with sophisticated skills for this kind of specialised work, and it helped when construction during lockdown slowed because many workers returned to their native villages. The overall labour cost doesn’t change much because you have to pay for the improved skills, even though its fewer people. But there are cost savings because of efficiency and time, and this can be from 5-15% depending on the scale of the project."
Satyanarayana added that using prefabs has led to the company up-skilling its workers, teaching them to use internet-enabled devices to assemble the different parts together. "There’s more supervision, monitoring and training that happens with cameras, handheld devices, to give directions on which parts go where," he said. "In the West, the methods of construction have changed and have become highly organised and systematic using modular and prefab structures. I don’t see us going back to the original labour-intensive way either."