According to the Barker review of housing supply, written in 2004, 250,000 homes were needed to be built every year through to 2016 to tackle the country’s acute housing crisis. But the construction industry has missed this mark every year since. More than a decade after the report was written, the number of homes built in 2015 stood at 137,490 – far below the target and a 1% drop on the previous year.
The Home Builders Federation blames local authorities for not fully adopting up-to-date local plans. It says that securing planning permission on sites has become “too complex, expensive and prohibitively risky”. But that’s only half of the story, because the construction industry is also in the midst of a skills shortage.
Last November, the government confirmed plans to build, by 2020, 200,000 starter homes with 20% discounts for the under-40s, 135,000 shared-ownership homes, 10,000 rent-to-buy homes, and 8,000 properties for the elderly and disabled. But Brian Berry, chief executive of the Federation of Master Builders, says: “Unless we see a massive uplift in apprenticeship training, there won’t be enough pairs of hands to deliver more housing on this scale.”
Factory builds are faster
The solution to the housing crisis will not be simple. But a major part of the answer may lie in moving house building away from the construction site and into the factory. Last July, the IMechE released a report saying that modular off-site building could be the solution to the housing crisis. Tim Fox, lead author of the report, said: “Overhauling the way the UK constructs homes could be the quickest and most effective way of doing this. Off-site construction technologies have advanced greatly and can offer shorter build times, better quality, energy efficiency, less waste, and lower costs for buyers.”
The report calls for the government to introduce a housing market reform programme aimed at growing the self-build sector, supported by UK-based off-site manufacturers, to supply at least 50% of demand (125,000 homes a year in England) by 2030.
But where do the UK’s off-site manufacturing capabilities stand? Laing O’Rourke, the largest privately owned construction company in the country, is investing heavily in its off-site manufacturing capabilities. It refers to off-site construction as Design for Manufacturing and Assembly (DfMA), an approach that focuses on “ease of manufacture and efficiency of assembly”.
Laing O’Rourke is moving much of the traditional on-site construction into the factory, creating standardised designs for products, for example concrete floor-slab elements, structural columns and modular plantrooms.
Raj Kotecha, engineering project leader for Laing O’Rourke, says: “Components are manufactured and preassembled in a controlled environment, prior to delivery to site for installation. The best results occur when DfMA is used in the conceptual stage – giving cross-functional teams, comprised of clients, designer and suppliers, the opportunities to optimise the design for reducing waste and achieving efficiencies, for example, by reduction in labour, build programme, carbon footprint and accident frequency.”
Laing O’Rourke’s main manufacturing centre is a 25,000m2 facility at Explore Industrial Park in Worksop, Nottinghamshire. Here, the company has used automated technologies and created a high-speed production line, using DfMA, optimised data flow and full CAD integration. Lean processes, such as computer-controlled hoppers for concrete pouring, and the manufacture of preassembled components, streamline construction, automating many of the traditional on-site processes and reducing the need for manual labour.
Streamlined process
Kotecha explains that DfMA uses building information modelling and 3D design software such as Rhino. “We make sure it’s a coordinated design across all disciplines, with mechanical, electrical and any follow-on trade,” he says. “It helps to streamline it. They are fairly generic products that can be rolled out time and time again, with a few core design principles. It all just comes down to delivering a better-performing asset to your end user.”
This all results in more control and insight into the design, down to whether a particular window may be prone to condensation, and better quality manufacture of the building parts. Kotecha says: “There is more control over things like joins between elements and how well the workmanship is done and put together as it is done in a controlled environment. You haven’t got guys out working in the open air and cold just wanting to get something done really quickly and then covering it up if it’s not perfect.”
Kotecha has recently been working on a 40-storey building at Elephant and Castle in south London. He was able to work closely with consultants from day one to design it as an off-site manufactured build. This, he says, meant they were able to drive efficiencies through the entire system.
“It has been a very refreshing way of working, tweaking a bit here and there to the client’s request,” says Kotecha. “We did the same around the mechanical and electrical side of things as well. We were able to pick up the pace in wiring modules getting made in the factory. You can drop it in, plug it together and you’ve got a finished lighting module that you know works and has been pre-tested.”
They are also beginning to use virtual reality googles so clients can visualise the space, and even decorative finishes, before it is manufactured.
DfMA tends to be 1% or so more expensive than traditional construction, but time saved thanks to the up-front design and coordination avoids a lot of costly changes that would otherwise have to be carried out later on site.
This approach has also helped Laing O’Rourke to continue building in spite of labour shortages, cutting the need for on-site staff by 40%. Kotecha says that 60% less labour would be the holy grail, which would mean the firm could invest more in training to create multi-skilled staff. “Fewer people on-site also means lower risk of people getting hurt,” he adds.
Laing O’Rourke has recently invested in a new factory for off-site construction that is expected to deliver up to 10,000 modular homes a year. It is a highly automated environment where 65-70% of the work is done by machines. The aim is that 90% of the housing module will be delivered off-site, with the remaining 10% finished on-site, with what Kotecha describes as a “plug-and-play mentality”.
He believes that off-site construction will increase quite significantly in the UK, and more houses will be delivered in this way, moving more in line with what happens in other European countries.
Testing prototypes
The Building Research Establishment (BRE), formerly a government agency, carries out research, consultancy and testing. It has been working on modular prototype builds in the name of affordable and environmentally friendly housing. It has built and tested these houses at the BRE Innovation Parks in Watford, Hertfordshire and Ravenscraig, North Lanarkshire.
One such build has been a zero-waste modular house at the Watford site, which has been delivered by Scottish consultancy Tigh Grian and Üserhuus, a Swiss, non-profit company that transfers technology from university research.
Dubbed “ultra-efficient structures”, they have been developed as an example of how intelligent systems can be used to provide quality housing for mainstream dwellings and hostels. They are made up of a single-bed apartment or a combination of units forming houses of up to four bedrooms. The 4.9m x 11.4m units can be assembled into buildings of up to four storeys or as detached, terraced and semi-detached dwellings, and four-in-a-block apartments. Each unit is built, serviced and finished ready for occupation in the factory, then it is transported by lorry to be laid on prepared foundations. Each unit is fully insulated on all sides and is fitted with uPVC windows. It is heated using a whole-house heat-recovery ventilation system, with wall-mounted electric panel heaters. There is also the option to replace the tiled roof with photovoltaic panels.
John O’Brien, principal consultant at BRE, says that one of the early challenges was in transporting the boxes: “If you want to move without a police escort you are limited to a 4.9m wide box by 9.9m long. Once you get over that width it gets expensive. We have to then build within those parameters.” To overcome this issue, it was decided to deliver the units unclad, and carry out the cladding work on-site.
Once on site the modular units must be lifted into place, which should take six hours, then it is a case of putting up scaffolding to add finishes, such as rendering, and roofing.
O’Brien says that the target for an average build time was six weeks, but it took slightly longer as they learned the process. “It is like one of those Ikea wardrobes, it takes 2 hours to do the first one and 20 minutes to do the next,” he adds. “But we’re happy that people do it slowly on our site so they can get all the learning rather than make the mistakes in dealing with real clients.”
Overall the cost per square metre came to £1,100, including the solar PV roof. While that may not be quite as competitive as traditional builds, O’Brien says those prices are rising, potentially as high as £2,000. In addition, the benefits of shorter build times mean lower overall costs for investors, and the buildings can be put on the market much quicker to recoup costs. The build can also be of a higher quality, more controlled, and the houses made safer and more energy efficient.
O’Brien believes that modular housing will play a part in the future in the UK but stresses that, while this will need the work of large manufacturers such as Laing O’Rourke, much more support from government will be needed for smaller firms. “You’ve got Laing O’Rourke saying we can produce 10,000 a year but if we can get 100 people each producing 50 houses a year on the production line that will be a major step in reaching 200,000-plus homes a year,” he says.
Government support for modular innovation
Laing O’Rourke and 21 consortium partners have been awarded a £22.1 million, four-year grant to support a £104 million project for the advanced manufacturing of homes.
The project work streams will not only address research into modular design and manufacturing, but will also cover training initiatives, providing skills in digital engineering, manufacturing and installation. Stephen Harley, director of advanced manufacturing at Laing O’Rourke, says: “It will create over 600 direct jobs and as many as 1,000 across the diverse supply chain.”