Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to the newest version of your browser.

Your browser appears to have cookies disabled. For the best experience of Construction News, please enable cookies in your browser.

Welcome to the Construction News site. As we have relaunched, you will have to sign in once now and agree for us to use cookies, so you won't need to log in each time you visit our site.
Learn more

The prefab sheds its soc cial stigma

PREFABRICATION - The Housing Corporation is demanding that at least 25 per cent of every new social housing development be built using modern methods of construction.But do manufacturers have the capacity to meet that target? David Taylor reports

NOT EVERYBODY is delighted by Deputy Prime Minister John Prescott's determination to add an extra 120,000 new homes to the housing stock every year for the next decade or so. Even those who applaud the policy doubt that industry has the manpower and skills to meet that target.

This is why the somewhat vague phrase, modern methods of construction, deployed earlier this year by Lord Rooker, is now in vogue.

MMC is being touted as the saviour of the skills-starved industry.

Luckily for anyone who is still left in the dark by the definition, the Government's social housing funding body, the Housing Corporation, has identified five generic types of MMC, four of which are off-site methods (see right).And it has set a target that at least 25 per cent of every new social housing development has to be built using these techniques.

There is no doubt this policy has given a major boost to manufacturers and designers of off-site systems. But Darren Richards, operations director at prefabrication consultancy Mtech, argues that adoption of off-site methods is already widespread.

'Ten years ago there were relatively few UK manufacturers operating within the off-site arena, ' says Mr Richards.'Today there are more than 400.'

Mtech calculates the UK market is worth about £1.6 billion but says it is growing at something like 30 per cent a year.Off-site production has, it seems, finally shed its 'prefab' stigma to become recognised as an efficient and attractive alternative to traditional methods.

In fact, client demand is so strong, says Mr Richards, that providing sufficient manufacturing capacity could soon become a problem. Cultural barriers also need to be overcome.

'Clients are pushing contractors to provide off-site solutions but the construction team set-up is usually very traditional, with contractor, QS, architect and engineer playing their usual roles, ' says Mr Richards. Even now, he adds, many projects that employ off-site methods often started out as traditional designs.

To persuade people to design for off-site methods from the outset, Mr Richards has joined forces with others in the sector to form the Off-Site Construction Alliance, an umbrella body that hopes to unite the various emerging technologies and to promote off-site principles throughout the supply chain.

Because of the Housing Corporation's commitment to MMC, demand for off-site methods is strongest in the social housing sector.Housing associations are building between 7,000 and 8,000 units of their 30,000-unit annual output using modern methods - assuming the 25 per cent quota is being adhered to.

'The pressure now is really on, ' says Mr Richards.'The Government wants the housing associations to build 60,000 units next year and it wants 50 per cent of them to be built using modern methods.'

The speculative house builders are not far behind the housing associations.All the top 10 house builders are exploring the use of off-site methods and some have invested heavily in their own systems.

'Timber frame is the basis of many of these systems, ' observes Mr Richards.'About 18 per cent of new houses today are timber-framed. In Scotland it is nearer 65 or even 70 per cent - and that's a big chunk of the market.'

So far the biggest investment in off-site production made by a speculative house builder is Space4, the company set up by Westbury Homes. Space4 produces panellised houses at its new £13 million factory not just for Westbury, but for other house builders, too.

'In the past three years we have produced about 4,500 units, ' says Space4 managing director Patrick Dormon.'This year our production will be 3,000.'

The Space4 factory has enough capacity to double this amount but Mr Dormon predicts that all spare capacity could soon be eaten up.

'A lot depends on our third-party customers - mainly other major house builders and contractors, ' explains Mr Dormon.'So far they account for about one third of our production but next year it will be a half or twothirds.Within two years we'll be needing extra capacity.'

Systems such as Space4 - that is, panellised as opposed to volumetric - are especially popular with commercial house builders, despite the fact that they require more site work to install them.

This is partly because many panellised systems are essentially extensions of existing timber frame: the studwork frames are insulated and internal and external skins applied in a factory instead of on site.This is a natural extension for the house builders, who are already geared up for timber-frame construction. But panellised systems also offer greater design flexibility and are more readily able to accommodate floorplan variations than volumetric systems.

A recent development is the Structural Insulated Panel System, which does away with timber studwork altogether. SIPS comprises a core of insulating foam sandwiched between two skins of oriented strand board or other board product.

But Darren Richards says that the fastest-growing sector is in lightweight steel frame technology.

'Timber has a lot going for it, but steel is catching up, ' he says.'In 2000 I knew of only four manufacturers of steel-framed systems but today there are at least 24 in the UK.'

Some manufacturers are even looking at the idea of setting up 'field factories', using mobile presses to convert flat steel sheet into rolled sections on site.The idea is that it is cheaper and more efficient to transport a roll of steel and a press on one vehicle than to carry several truckloads of finished studwork to site.

For many, volumetric is the ultimate expression of off-site manufacture.

Michael May, property director of social housing landlord the Peabody Trust says: 'For me, volumetric is the best way.The more you can do in the factory the better, and safer, the process becomes.'

And for social housing, this is probably true. Peabody Trust's latest development, Baron's Place, near Waterloo Station in central London, is a low-cost relocatable complex of nine micro-flats for key workers. It follows on the heels of two award-winning developments, Raines Dairy and Murray Grove, both of which were also built using volumetric units.

Much of the new housing envisaged by Mr Prescott will, ideally, be built on brownfield sites in urban areas.And if the problem at hand is that of an acute shortage of affordable housing, then there's no doubt that the quicker and more cheaply you can build, the better.