For more than two decades, the widespread adoption of offsite prefabrication has been almost universally accepted as a fundamental requirement for the modernisation of UK construction.
It’s a no-brainer: better quality and less waste thanks to controlled manufacturing processes; faster completion thanks to just-in-time delivery and rapid assembly; and better health & safety standards, thanks to vastly-reduced requirements for on-site operations.
Pre-fabrication – now more popularly referred to under the catch-all phrase of “modern methods of construction” (MMC) is especially suited to residential developments. And while many developers in the social housing sector have embraced MMC in various forms, the big volume house-builders have merely dabbled with the idea.
Despite a chronic shortage of new homes and an ambitious government target of 300,000 new homes a year, the vast majority of houses currently being built still employ the same old formula of brick-and-block cavity wall construction, all built on site, mostly by hand.
“There is government pressure to adopt more offsite,” concedes Bob Weston, chairman and CEO of the £200m-turnover Weston Homes Group, “but people have been slow to adopt offsite methods.”
Slow or not, Weston is conspicuous among major house-builders in having taken the plunge and embraced prefabrication not just for its own new homes, but also to supply third parties through a separate standalone business.
In 2019, with £35m of investment, Weston set up British Offsite, a new business occupying a 75,000ft2 factory in Braintree, Essex, to design and manufacture its own system, UniPanel, a modular ‘hybrid’ offsite construction system suitable for residential developments.
Now, just three years later, British Offsite (under the direction of managing director Shaun Weston, Bob’s son) has started construction of a second, much larger, factory at the Horizon 120 business park in Great Notley, just outside Braintree. Scheduled to open at the end of this year, the new 137,000ft2 factory will employ up to 80 people and produce the UniPanel system including light-gauge steel panels, walls, roofs and floors alongside internal fit-out modules including bathroom, kitchen and bedroom components.
The new factory is being equipped with £6m-worth of robotic machinery from Swedish firm Randek, which designs and manufactures automated production systems specifically for the manufacture of prefabricated houses.
Weston’s enthusiasm for offsite manufacturing is partly explained by his company’s business model. “Our product isn’t your typical greenfield housing development. We use about 80% brownfield sites and we mostly build apartments,” he explains.
The company is currently working on a number of urban infill developments, including Anglia Square, a 1,000-unit development in Norwich; Abbey Quay, a waterfront development of 1,200 apartments in Barking; and Lorimer Village, £500,000 mixed-use development including 1,400 new apartments on the site of a former Tesco supermarket in Redbridge.
The use of modular kitchen and bathroom ‘pods’ in the construction of multi-occupancy buildings is well established and Weston’s entry into the offsite sector was therefore a logical development for the company. “The fit-out side has been going for about six or seven years,” says Weston. “Originally we had our kitchen, bathroom and bedroom kits made in China and then about four years ago we started making them ourselves and opened the first factory in Braintree. From there we started the UniPanel system,” he adds.
Weston says that British Offsite’s UniPanel system is a hybrid MMC designed to be very flexible and allow rapid integration into traditional building design. The internal fit-out modules, marketed under the BOS Fitout brand, are also designed to be easily integrated into existing projects, with full quality control testing before the elements reach site.
One of the main reasons offsite prefabrication has failed to take off as successfully as people had hoped is that it’s “too system-driven,” says Weston. He points out that there has been a plethora of different MMC systems rolled out over the years but the market lacks the flexibility to accept them all.
He cites the Wimpey ‘no-fines’ home, a post-War prefabricated system designed by George Wimpey and employing a porous concrete mix containing no fine aggregates. These houses helped to deliver much-needed new homes very quickly but their construction proved controversial in later years.
“They became un-mortgageable because they were deemed ‘non-standard’ construction,” says Weston. The problem persists today, with mortgage lenders and insurers still very reluctant to approve houses built of anything that isn’t fully certificated and time-proven – hence the continued popularity of ‘traditional’ brick-and-block. Concrete seems to be a particular bugbear for the financial sector, despite the material’s proven longevity in bridges, dams and other load-bearing structures.
With British Offsite’s UniSystem, Weston has managed to circumvent these problems. “Our panel system is essentially exactly the same as what you’d build on site, only it’s made in a factory. We’re not reinventing the wheel,” he adds. In other words, the UniPanel system’s innovation has more to do with the process than the product itself.
“Ours is a hybrid system. It’s not volumetric and it’s not fully-finished. But the panel with its concrete frame is what gives you your structure,” explains Weston. Pre-fabricated panels are delivered to site and assembled with all the benefits of an offsite MMC, but traditional trades, such as plastering and painting are used to finish the interior on site.
All of British Offsite’s systems are fully certificated and approved, so there is no problem with mortgage applications or insurance, confirms Weston. “We had to go through the whole approvals process with NHBC, BRE and all that,” he says.
Hence the UniPanel system is approved by the “NHBC Accepts” scheme for new and innovative systems, and components all have the relevant accreditation compliance.
The British Offsite product line is therefore versatile and readily accepted, making offsite a natural evolution for developers, Weston believes. It also has another, very significant, advantage for today’s developers: it is not dependent on traditional building skills.
“The skills shortage was a major reason for us going into this,” Weston says. “Hardly anybody in our factory comes from a construction background. None of the people working on our bathroom line are plumbers. It’s an entirely different labour force,” he explains.
Without a dependence on site skills that take years to acquire, British Offsite is able to set up production lines that can rapidly start manufacturing building components in considerable volumes. “We can work round the clock,” says Weston. The original factory is currently working three shifts, 24 hours a day.
At present, nearly all of this output is for Weston Homes developments, but the aim has always been to supply third parties. The new factory will be used to increase production four-fold; and it will also be crucial in developing new systems.
Weston says that British Offsite is currently developing a new light-gauge steel-frame system for houses – called, naturally, UniHouse. “We’ve already built three experimental houses with the system on a disused airfield in Essex, but it’s still a couple of years away from being launched,” he says.
First, of course, the new factory needs to be finished and the production machinery installed. British Offsite expects to take possession of the building in August and complete the fit-out before the end of the year. In the meantime, Bob Weston is keen to stress that he’s not just about offsite – he’s a pragmatist.
“British Offsite is a separate company – it has to stand on its own two feet. But I’ll do anything,” he says. “We’re currently converting an 1857 Grade II listed building in Aldershot…”