New Delhi: Labourers preparing concrete manually in worn-out mixing drums could become a thing of the past, and so could the women balancing bricks on their head as they walk up brittle bamboo ladders.
Facing a shortage of labourers, builders in India are resorting to new ways to meet the unprecedented construction demand in one of the fastest growing property markets in Asia. Prefabricated building systems that have been traditionally used in India to build bridges, metro rails and industrial units so as to save money and time are now finding their way into constructing homes.
“Using prefabricated materials has made construction work easy,” says Vinay Khurana, a structure consultant for builders. “When we use prefabricated materials, it brings down the construction time by as much as 50%. Though using such materials is more common abroad, prefabricated structures are used in India in (only) large construction projects.”
While using prefabricated materials is more or less the norm in building projects in sophisticated markets overseas, the trend has just started here, because of the construction boom and Western architectural influences.
Now, more and more builders are opting for prefabricated materials to cobble together large structures without having to employ armies of labourers and monitor the uniformity of their project work.
“Because of quantum of delivery, people have started preferring prefabricated materials,” said B.P. Dhaka, chief operating officer, Parsvnath Developers Ltd.
Prefabricated materials are essentially ready-to-fit materials manufactured at a factory outside the construction site. They are later assembled at the construction site by masons and joiners.
And it is taking over almost every aspect of construction work. Builders are, for instance, using pre-mix concrete instead of preparing a cement and sand mixture at the construction site. This has helped in speeding up construction.
In prefabricated construction, only the foundation and floor slabs are constructed the conventional way, which involves transportation of bricks, timber, cement and sand to the building site. Sections of walls and roof are fabricated at a factory—sometimes with windows and door frames attached—and transported to the site, where they are bolted together.
Builders either source the materials from third parties or manufacture them on their own if the projects are big.
Parsvnath, for instance, makes pre-mix concrete, small beams, special marking poles, curved stones and special purpose pipes at Ujjain in Madhya Pradesh and Sonipat in Haryana, where they have projects, so they can cut down on transportation cost and time.
“Right from the marking poles used in demarcating boundaries of buildings to sewer pipes, developers have started making it themselves,” says Parsvnath’s Dhaka.
Prefabrication can save time and as a result cost, says G.B. Singh, director, Red Fort Capital Advisors Pvt. Ltd, a private equity real estate firm, which plans to build low-cost homes using prefabricated materials. For instance, casting of a super structure, where the structure of a building above the ground level takes 7-28 days if the casts are made at the construction site. But if the casts are made at a plant outside the construction site, it takes just seven days.
It also gives better quality of work, says Singh. “When you work at the construction site, it is prone to bad weather like rain or sun. The quality of work is better when the materials are manufactured at a factory shed where you can control the conditions at the ground level.”
Red Fort Capital plans to use concrete based on fly ash for its projects, instead of bricks, as fly ash has better thermal efficiency. “Fly ash is a waste material which is easily available at every construction site. So, we also save on costs,” which is an important element in low-cost housing, Singh says. In many ways, prefabrication also lowers the cost of construction because there is less wastage, pilferage and better storage in factories compared with on-site work.
What’s better, an almost robotic uniformity is easy to replicate with large townships and projects because the concrete or other building material used is poured into moulds that churn out rows of similar-looking stuff.
Industrial moulds, unlike casts, can also be used several times. “If we make casts on the construction site, we use a timber mould, which can be used to make casts three-five times. But if we make it off-site, we use steel moulds in which we can make casts 500-1000 times,” says Singh.
For prefabricated buildings, steel moulds are better, though they are more expensive than timber moulds. While timber moulds cost Rs150-200 per sq. ft, steel moulds cost three times more. “When there is a larger use of the same mould, like in the case of large projects, it is advantageous to use steel moulds,” says Singh.
As large pieces of the structure come from a factory and the materials can easily be assembled on-site, builders reduce on-site costs on labour compensation, site supervision and inspection. The use of prefabrication can provide a cost saving of 15-20% over on-site construction, says Singh.
It also improves the productivity of labourers. “Labourers who produce materials on a large scale are usually unskilled labourers. Labourers become experts in what they do as they are doing the task repeatedly,” adds Singh.
Still, not every developer can take advantage of the system. The downside of prefabricated materials is that it makes sense only for very large projects.
“In large projects, whereyou are building more than 300 flats, every flat will have four-five windows, so, itmakes sense to have ready-made window beams which expedites construction time,” says Dhaka.
While it is difficult to put a figure on the cost savings on a square-feet basis, according to Singh, the cost per unit reduces as moulds are used repetitively.
Although prefabrication is being used on a growing number of projects, most construction work is still site-based. Real estate developer Eros Group, for instance, has not taken to prefabrication.
“We don’t use prefabricated materials as we are not working on several large projects,” says Kaushik Sengupta, vice-president, marketing, Eros Group. “It is mostly the large developers who use this method of construction.”