The UK needs more houses. About 250,000 a year, according to some estimates, to stabilise prices and provide enough affordable homes. But the country only produced 164,000 for 2015/2016, according to the National House Building Council.
While part of this failure is down to red tape and the planning system, the recent Farmer Review of the UK Construction Labour Model puts the issue plainly: “Modernise or die”. A veteran of the construction industry and head of Cast Consultancy, Mark Farmer says a potential 20%-25% decline in the available labour force within a decade will further damage hopes of hitting any targets, including the government’s for 200,000 a year.
Farmer’s solution? Move to pre-manufactured solutions.
Farmer name checks Laing O’Rourke and Legal & General’s new mega-factories as two of the biggest examples of best practice in increasing the predictability of time, cost and quality.
But many other smaller companies are also springing up both in the UK and overseas to service the growing sector.
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One such is Vision Modular Systems, associate company of Tide Construction. It has about 150 staff at its Bedford manufacturing hub where every year 2,000 modules of steel-framed walls and concrete floors are fully fitted out and shipped to the UK and Europe. Two of these modular units are sealed together as whole single-bedroom apartments, dispatched on the back of a trailer and hoisted into place on site.
The latest example of Vision’s modular approach is Savoy Circus, a purpose-built student accommodation scheme on the site of a former cinema in Acton, west London. The halls of residence will stand at seven storeys, offering 306 studio apartments, 338 modules in total, with communal spaces – all going up in less than six months.
“We are looking at programme savings of circa 50% compared to traditional build,” says Vision’s managing director Kieran White.
“Assume you have a site where you have site clearance, you’ve got piling underground preparation work, deep basement, all the rest of it,” explains White. “Once all that’s been done we can get on to the fine detail work, manufacturing the modules in the factory, and once the above ground work, base levels, concrete cores are in position we can start lifting modules and installing them.”
It is at this stage where most of the time saving happens – the structures go up extremely quickly, at a rate of about 15 modules a week.
To succeed in this sector, companies must initially develop their own proprietary systems, developed over years or decades, with varying modular system types for steel, cross-laminated timber and pre-cast concrete.
The next challenge comes on individual projects. When more design work is done up front, the client needs to be convinced that more resources need to be committed early on in the programme.
“That earlier decision making is difficult for some projects, particularly for some clients, but it’s just a different way of thinking and once you’ve been through one it just becomes a way of working,” says White.
“I think for the consultants, whether they be architects or engineers, there isn’t that much difference, apart from a little earlier engagement.
“We’ve worked with a lot of architects, they get it quite quickly once they realise how the system works and what the particular wall build ups are, how you can handle junctions in one module and another.”
Another hurdle is preconceptions about the aesthetics of modular housing: cheap, boxy and impersonal. But White says this is ill-informed, and an outdated legacy from what “prefabricated” used to mean.
“We challenge them in this regard. We include features whether they be oriel windows, mansard details, balconies, cantilevered modules.
On the whole I think it is true there is that perception, but it’s a perception from those who haven’t analysed and thought how to apply a modular solution.”
It’s just a different way of thinking and once you’ve been through one it just becomes a way of working
Kieran White, Vision
Perceptions around how high modular can go are also changing. While there are some claims about a modular skyscraper built in China in 90 days, the world’s tallest modular building is more likely be the 32-storey residential tower in Brooklyn, in the United States. It comprises 960 apartment-sized modules and the developer claims 90% of the structure was built in a nearby factory.
Vision is not far behind, going up to 28 storeys, says White, adding that there is no upper limit on modular, as long as the loads are based around an insitu concrete core.
“From a structural engineering perspective, you do need to think about that vertical load transfer. You’ve got some flexibility in terms of varying layouts, and it’s got to be within reason, but as you stack one storey on top of another, you try to get that vertical load transfer along a number of grid lines.
“We always try is to steer clients towards putting tank rooms and other heavy localised loads in basements or on ground floors, because if it’s further up such as on the roof, the load-bearing walls will need additional steel for strengthening.”
Vision’s system has passed various standards, including CE accreditation, and has endorsement from the British Board of Agrémont, Local Authority Building Control and the Buildoffsite Property Assurance Scheme. “All of those are badges of pride which we carry that say this system has passed the tests for these various institutions, which happen almost on a six-monthly basis. Then we have our own quality control team to make sure everything, from the structure to the fire performance, is above board.”
But one thing Vision has yet to truly measure is the carbon benefit of the system over insitu building. It is confident its system is better due to faster speed of construction. White says about 90% less waste is produced on site over traditional build. There is also 75% less personnel on site, and 60% less deliveries.
Most of these advantages are already well known. Pre-fabricated housing has been in the lexicon as far back as the 1970s for public housing. So what’s behind the latest big push? And where is it heading?
White says in the last couple of years a number of large companies have committed to modular. “Clearly Laing O’Rourke has been vocal in its commitment to it. Then Legal & General, firstly committing to getting into the private rental sector, shortly afterwards announcing it would work on delivery, and a key way to enable that is building its own factory. The tier one contractors are making statements that I think have given a lot of confidence to the sector.
“The other thing is that businesses such as ours have become assets that are readily accepted by the investment sector, which is becoming extremely keen on modular production techniques.”
Private rental opportunities
More activity in the private rented sector also lends itself particularly to modular manufacturing, says White: “Let’s say you take a scheme with a couple of hundred units in it. And if you’re building that speculatively and it’s for private sale. The developer will want to assess the market, hold off on decisions such as level of the fit-out, see what the sales rates are looking like. That flies in the face of efficiencies in having it pre-manufactured offsite.
“Whereas within the rented sector the developer/owner-operator of that will be upfront, saying ‘yes, I want a mix of types and will want to know exactly what they’re fitting it out with’. So it lends itself to those decisions being made earlier in the contractor client discussions.”