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Take off-site

Modular and off-site construction is finally beginning to grab the industry’s interest. Could it revolutionise housebuilding?

David Blackman, Journalist
6 April 2018

Japan’s consumer giants are household names worldwide, providing us with TVs, cars, stereos and even sewing machines. But in their home market, the likes of Panasonic and Toyota are also well known as housebuilders, applying cutting-edge industrial manufacturing techniques to a sector that still relies on pre-industrial skills in many parts of the world.

And according to the Farmer Review of the UK Construction Labour Model, which was published in October 2016 by the government’s Construction Leadership Council, Asian developers are now thought to be eyeing up off-site construction as a way of breaking into the British market.

Asian housebuilding factories

Stewart Dalgarno, director of product development at the Scottish-headquartered contractor Stewart Milne, was deeply impressed on a recent tour of Japan’s housebuilding factories. The Sekisui House modular factory that Delgarno visited, in Shizuoka prefecture, looks more like a car plant than a construction site. The factory contains around 150 robots, each equipped with an arm that is able to manoeuvre on five different axes, in addition to being capable of spinning around on themselves.

The first stage of the process involves robots cutting the panels from which modular frames are constructed. Lengths of steel are picked out by the robots from racks in the factory’s warehouse and brought gliding across to the head of a production line, where the cutting and shaping of the panels begins. The steel sheets are then bolted and welded together to create the cross-braced modules that will be used to make up the new homes.

After the modules have been assembled, hand labour takes over for the fitting-out process. Once clad and insulated, the modules are winched on to the back of a lorry and transported to a waiting site.

The Sekisui House factory in Shizuoka can build 4,000 homes a year – a sizeable chunk of the 140,000 homes built in Japan during 2014 using off-site techniques, which equated to approximately 15% of the nation’s housing output.

Singapore & Europe follow suit

The Singaporean government has also spotted the potential of off-site housing, and uses policy to support the industry. Developers can only bid for publicly owned sites, which comprise much of the city state’s land, if they are prepared to build a minimum percentage of the homes using off-site methods.

Singapore believes that the use of off-site techniques can double the efficiency of the construction process, which is why its Building Control Association has ploughed $250m into an initiative to support the use of these methods. Dragages Singapore, the local arm of the French conglomerate Bouygues, has announced that it will be building two 40-storey residential tower blocks using predominantly modular techniques.

Factory-built housing has also taken off in parts of Europe. In Germany, 9% of new residential building permits issued in 2013 were for prefabricated homes, figures from the country’s Federal Statistics Office show. Off-site housing in the country tends to be used for small, one- or two-dwelling developments, rather than bigger building schemes.

“[The Germans] are absolutely willing to try new things out. There is more competition [than in Switzerland], so the Swiss industry has had to think about how to produce more housing, more cheaply.” - Norbert Zimmerman MRICS, senior consultant, Halter AG.

Off-site building is popular in the Netherlands, too. Around one-fifth of all new housing built in the country uses wood or concrete prefabrication.

But it is probably the Nordic states that have embraced the building of manufactured homes most enthusiastically. Around eight out of 10 detached houses in Sweden are built using prefabricated timber, and the climate has been a demand driver.

The harsh Scandinavian weather has encouraged the use of off-site frame-and-panel systems, says Rory Bergin, a partner at London-based architect HTA. “They have a short building period, so you are employing people in the winter to build stuff and employing them in the summer on site.”

Off-site building methods

The use of off-site building methods remains patchy across the world, though. Just 3% of new housing in Australia is being built using off-site methods. That figure is barely higher in the US, where the more traditional building techniques hold a stronger sway on the more heavily unionised east coast than on the western seaboard, according to Mark Farmer MRICS, the CEO of consultant Cast, who examined the take-up of off-site construction around the world for his eponymous review.

In the UK, which has been through several stalled initiatives to increase the off-site manufacture of housing over the last few decades, the picture has become more optimistic and could now be changing.

The principal factor driving renewed interest in Britain – as well as in places such as Australia and Singapore – is a shortage of skilled labour.

In the UK, this problem is likely to be exacerbated by the outcome of the country’s 2016 referendum vote to withdraw from the EU, because workers from member states have traditionally plugged the industry’s skills gaps. “We didn’t do this in the past because we could rely on an influx of workers from the EU. We won’t have that in the future,” says Bergin.

And the UK government’s drive to increase take-up of apprenticeships will not deliver in time, warns off-site construction consultant Dennis Seal. “Apprentices are great but they take three years to fully train. That would mean it would be 2020 by the time we had the right skills in place. In a factory, you can bring labour up to skill in about three months.”

In addition, women might be more likely to take on a job in a factory than on a construction sites, given the latter’s reputation as havens of sexist behaviour. At the Swedish modular construction company Lindbäcks’ factory, where the timber beams are fed into machines that align and fasten them into frames, around half the staff are female.

Seal believes that the UK construction industry simply will not be able deliver its government’s target to build one million new homes by 2020 with the existing labour force. “We now have a huge gap between housing demand and existing housing supply. At this time, about 150,000 homes can be built in the UK with the current restriction of materials and labour, but the demand is for 250,000.”

And off-site housing has other benefits. The homes themselves can be made wind- and weather-tight more rapidly because they have been assembled off site, thus minimising the risk of damage from the elements during the building process. And the more precise nature of the factory manufacturing process should mean fewer snagging defects. As for the technical problems that bedevilled off-site construction’s reputation in the past, the panel-based systems that triggered the collapse in 1968 of the Ronan Point tower block in east London – two months after it had been opened – would not be allowed today.

Meanwhile, the use of the cross-laminated timber, which is increasingly common in modular homes, provides a building material that is not only strong but is more sustainable than concrete, and, with safety in mind, fire-resistant, too.

With the spread of innovations from more technologically advanced industries such as automobile production, Farmer believes the time is ripe for the UK’s own off-site housing revolution to take off: “We’ve been here before, but I’ve never seen the stars so auspiciously aligned.”

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