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Fleming stacks the odds in its favour

STEEL - While off-site construction is common, few firms are taking it to the heights of Fleming Developments UK. Michael Martin, the firm's business development director, tells Alasdair Reisner about its latest modular scheme

THE ARTIST'S impression of how the Houndmills residential scheme - currently under construction in Basingstoke - will look is pretty 'normal'. It is a standard example of modern highrise residential architecture.

The completed scheme, being built by Fleming Developments UK, will appear little different from any one of 100 apartment projects being built, but this job relies on innovation.

All of Houndmills' 162 apartments - split over three blocks - were largely created by a dedicated team working across the Irish Sea at Fleming's factory in Cork and not on-site.

But prefabrication is not uncommon these days. What stands out here is that previous off-site jobs usually involved slotting preformed pods into a frame that had been manufactured onsite, the Houndmills development gets its structural strength from the modules themselves, which stack together like Lego bricks.

'The system we are using is totally modular, which enables us to do all the basic structure and fitting out works in the factory.

We have developed a structure module that allows us to stack them without any external frame support, ' says Fleming Developments UK business development director Michael Martin.

The modules are formed in the factory using heavy section steel to create the floor dimensions, in which a reinforced concrete floor is laid. The walls, which are manufactured from hot-rolled steel section on a parallel production line, are bolted on. These wall sections are faced with boarding that satisfies fire and building regulations and comes with all the necessary plumbing and electrics prefitted. The modules are topped off with a ceiling void, again made out of hot-rolled steel section.

The overall result is a structural box that can support the loadings of the modules above it.

Fleming's system is still going through its patent application and BRE certification, so Mr Martin is unwilling to detail precisely how the system locks together for fear of helping rivals develop similar systems but he does outline the construction technique.

'We do it floor by floor, ' he says. 'The way the modules are made up depends on where they are in the building. In general terms, for a 1-bedroom flat we use two modules, for a twobedroom flat we use three.

'Whatever happens, as the building goes up the walls for the modules follow through so the down forces are properly loaded.

You cannot afford a situation where they stagger and the loadings are transferred in the wrong way.'

Regardless of how it works, Mr Martin believes it is the tallest example of fully modular construction in the UK. Furthermore, he expects Houndmills to be just the beginning and to be able to go even higher in the future.

'The way we have designed the modules currently, the loadings we have will allow us to go to 12 storeys. If we wanted to go above 12 storeys we would need some research and development to design the modules with greater structural capacity, but we are always looking to improve the product and expand our opportunities, ' he says.

And height is not the only area where he thinks the product can be further improved. Despite being largely prefabricated in the Cork factory, the Basingstoke project required in-situ poured concrete lift and stair cores.

'In the future, ' Mr Martin says, 'we are looking to see if we can produce the stair cores in a modular format off-site so the whole development becomes built on the off-site principals.

'We also see our service as being able to provide the complete package. If we have complete control of the structural engineering for the in-ground activity as well as the above ground activity, they can be interactive to each other, which can achieve benefits in structural integrity, control and cost.'

The benefits in terms of speed of construction are already obvious at Houndmills, where the development is rapidly taking shape.

'We came on site on July 1, 2006, ' Mr Martin says.

'We started bringing in the first modules on October 25. The modules for the first block were in position by November 23 - that's 52 apartments, which is approximately 175 modules.

'We are in effect bringing in seven to eight modules a day and it takes around one hour from the time the vehicle arrives on-site to the time the module is positioned on the block.'

When the project was submitted for planning it had been anticipated that it would be constructed using a mix of traditional concrete and timber frames. Yet Sentinel, the housing association for which Fleming is developing the site, was keen to look at the opportunities afforded to it by the use of off-site techniques.

In doing so it managed to bring delivery time down from the 22 months anticipated for the traditional build to just 12 months for Fleming's scheme.

'That means that Sentinel is going to be able to provide housing for the local community almost nine months earlier.

That is a benefit for everybody, ' says Mr Martin.

But he points out that the benefits are not just in the speed of construction. 'Quality standards are far ahead of what one would normally expect with on-site activity, ' says Mr Martin.

'The quality of decorative finishes, the proximity and way in which electrical boxes are finished, the standardisation of fittings for the kitchens - everything is at right angles, there is nothing botched. It is very precise.

'Most contractors argue that they have to work to a 25 mm tolerance. We work as a principal to zero tolerance.'

The system also saves on resources, since labour costs per apartment are massively reduced by building in a factory.

Fleming has about 30 workers on-site compared with the 200 that might be expected on a traditional scheme.

'Although you have an overhead in terms of the factory, the labour costs and material costs are much lower, ' says Mr Martin.

'There is a balance but at the moment we appear to be ahead of traditional construction in terms of cost, ' he adds.

So, with improved cost, speed and quality performance, it appears that, despite its outward appearance, Fleming Developments UK's work at Houndmills is any thing but ordinary.