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A new school of thought in prefabrication

It took a week to erect and required no scaffolding. David Taylor discovers how a new school sports hall in north London is taking prefabrication to new heights

FOR ANYONE over the age of 40, putting the words 'prefabricated' and 'school' into the same sentence is likely to rake up bleak memories of freezing-in-winter, boiling-in-summer classrooms on wheels.

But the pupils of Winton Primary School in Islington, north London, are unlikely to grow up with similar prejudices.And that's despite having just acquired a prefabricated sports hall.

Clad in stylish cedar panelling and sporting a rakish monopitch roof, the new sports hall at the school is certainly a great advertisement for what industry fans prefer to label 'off-site manufacture'.

Just to make it even cleverer, it's sitting on top of an existing singlestorey Victorian building.The brains behind this concept are designers from consulting engineer James Lupton and steel giant Corus.

'We had been looking at systems for building structures like sports halls for some time, ' says Kevin Lane, general manager for modular buildings at Corus.'We had been in discussion with Sport England, which was interested in ideas to build new, better sports facilities.We also got talking to structural engineering consultancy James Lupton, which was already developing an idea for a panellised building system.'

The discussions evolved to a point where a workable system began to emerge. It became reality when architect James Pickard came to hear of it.

James Pickard's practice, London-based Cartwright Pickard, is probably the UK's most committed architectural champion of off-site manufacture.

Among its achievements is the multi-award-winning social housing development, Murray Grove, built for the Peabody Housing Association in Hackney, north London, two years ago. It was a five-storey apartment block, based on a modular lightweight steel-framed unit manufactured by Yorkon.

Cartwright Pickard was the architect and client's agent on the project to develop a new sports hall for Winton Primary School; it had done the basic design work, sorted out the planning and was inviting teams to bid for the contract.

To say that Corus walked straight into the job would be stretching a point, although there is no doubt that in Cartwright Pickard it had found a kindred spirit.

'But we're not building contractors and we knew we needed a partner which could deliver the building, ' says Mr Lane.That partner turned out to be Bluestone, whose parent company, Morgan Sindall, already had links with Corus and was interested in developing off-site methods.

This loose gathering of interested parties quickly joined up to form a team to develop the system - provisionally dubbed Quantum CF (CF standing for Composite Fastbuild) - specifically for the Winton school contract.Although Cartwright Pickard was philosophically inclined towards a pre-fab solution, the client, Cambridge Education Associates, wanted best value and the job went out to competitive tender.

The Quantum CF bid was not the only innovative solution proposed (all the others were conventional off-site proposals) but at £860,000, also proved to be the cheapest.Not bad for a system that has yet to benefit from the efficiencies of a dedicated production line and is still far from standardised.

'If we were producing larger volumes, the price would come down even further, ' says Kevin Lane.'However, we put in a realistic bid and we were still the cheapest.'

The team is already looking ahead to new projects.'We're talking to Corus about bidding for a PFI school project, New North Community School, also in Islington, ' says Bluestone operations director Farid Safavi.

'Morgan Sindall is leading a consortium bidding for the contract.This is where we will get to develop the system.'

View from the site FARID SAFAVI, operations director at contractor Bluestone, took a hands-on role in the Winton Primary School project.

'Because we were building off an existing structure, there was a lot of traditional construction work to do, such as underpinning and strengthening.We also had to ensure compliance with the Building Regulations and Disability Discrimination Act as well as provide costings - these things aren't what Corus is about, ' he says.

Bluestone also advised on the buildability of the Quantum CF system.

'The original idea was to erect the wall then put the roof on top, ' says Mr Safavi.'We were able to point out the benefit of getting the roof section into place as soon as possible so people could start working inside.'

He adds that once all the 'traditional'work was done, the erection of the sports hall took no time at all: 'It went up in less than a week.Normally, you'd allow four to six weeks for a steel-frame, steel clad building of this size.'

Nearly all the erection and installation work was done by a team of five workers: three erectors, a crane operator and a lorry driver.With only a few bolts to connect, the erectors could carry out the work very quickly from the safety of a mobile access platform. Remarkably, given the fact that this was a first-floor structure, no scaffolding was required.

The project was handed over in three phases, each snag-free, says Mr Safavi.The panels fitted perfectly and it only remained for the electricians and dry-lining specialists to come in and install the services and interior finishes.

This is one area Mr Safavi believes could be further refined.'The next step will be to include the M&E services and internal finishes at the manufacturing stage to reduce the amount of on-site fit-out required, 'he says.

Mr Lane agrees: 'The building envelope is really just a big dumb space.

The big win will be in fit-out; modularisation there will really pay dividends.'

Engineer James Lupton agrees but warns there is a catch to building more into the individual components.

'Things like M&E and the position of doors and windows are often subject to the client's whim and are frequently changed at the last minute, ' he says.

'If you're going to build these things in before you get to site, you've got to be sure that the client isn't going to change its mind.'

To preclude this at Winton Primary School, Lupton used 3-D modelling to walk the client through the project in virtual reality.'Without 3-D Nearly all the erection and installation work was done with a team of five workers.

modelling, Winton would have been a lot more difficult.And once you start changing things on site, you lose the whole benefit of off-site manufacture, ' says Mr Safavi.

Project details Building footprint:20 m x 20 m Building height (first floor):6.8 m Weight of structure:120 tonnes Number of panels:45 Panel size:7 m x 3.3 m (walls) 15 m x 3.3 m (roof ) Average panel weight:3 tonnes Bluestone on site: from February 2004 to September 2004 Erection time for Quantum CF structure: one week Total project cost: £860,000