黑洞社区

Architects dream of designing the perfect school, but in today鈥檚 climate that鈥檚 no easy task. Multiple stakeholders and short timeframes put pressure on the design process and all too often the end result is a compromise. No wonder so many recent schools are lacklustre boxes, containers at best and hardly inspiring.

At Leigh City Technology College in Dartford, Kent, one of 36 new national 鈥榓cademies鈥�, the challenge is not about the architect fighting compromise, it鈥檚 about how the constructors realise the architect鈥檚 intentions through detailed design and quality workmanship.

No doubt encouraged by the greater design focus the government鈥檚 flagship academies programme allows for, 黑洞社区 Design Partnership (BDP) has shunned the box approach and had some fun 鈥� especially with the roof. Curved facades blur distinctions between it and the 鈥榳alls鈥� while conical turrets and ETFE pillows provide cover to 鈥榳inter gardens鈥� and classrooms.

As Peter Vernon, project manager for main contractor Galliford Try, puts it: 鈥楾here鈥檚 lot of concept in there.鈥�

The complexity of the roof鈥檚 design means the 拢1.5m roofing contract had Lakesmere鈥檚 name 鈥榳ritten all over it鈥�, according to the specialist鈥檚 construction manager Tim Rowley. With the Welsh Assembly and the Xscape ski-slope in Renfrew in its portfolio of projects, he has a point. And while the firm can draw on a decade of experience tackling tricky builds, Rowley believes two factors eased the whole process: a great 鈥榩artnering鈥� relationship with Galliford Try which meant Lakesmere got involved as early as the two-stage tender process would allow; and the use of 3D logistics software. 鈥業t鈥檚 minimised risk from the outset,鈥� says Rowley (see box).

The 拢28.5m design and build contract involves the construction of four three-storey 鈥榗olleges鈥� and a sports hall. CM was on site just as Lakesmere was placing the first sections of roofing on the most striking part of the school鈥檚 design 鈥� a block, crescent-like on plan, the south elevation of which is a curved roof strung across massive glulam beams that arc down to ground level from a height of 12m.

As we watch the first few sheets of Kalzip being placed, Rowley explains some of the challenges arising from the unusual design. 鈥楾he roof is purlin-free, so we鈥檙e using large-span decks 鈥� up to nine metres 鈥� but space restraints and the building鈥檚 form makes access difficult.鈥�

Given more time during the client driven stage, we could have made our own decisions about detailing

Too big to be manhandled or forklifted, Lakesmere designed brackets so the decks could be craned into position. 鈥榃ith some of them to be placed in the near vertical, we need to take their weight while we fit them,鈥� adds Rowley. But once the decking is fixed, and the fire stops and insulation quilts have been topped with a vapour barrier, the smooth surface is too hazardous to work upon. Another temporary design is the solution: a curved crawler board that allows harnessed tradesman to complete the build up safely.

With roofing on the critical path the relationship with Lakesmere is paramount, says Vernon. 鈥榃e鈥檝e got to make the roof work. So we鈥檒l sit down with Lakesmere and thrash it out. We鈥檝e got to be able to take it back to BDP and say 鈥渨e can see your intent, here is the detail鈥�.鈥� The contractor got Lakesmere in as early as possible so they could work on the key issues together: logistics, acoustics, fire stopping, how it fits within the wider programme and how to get it watertight as quickly as possible. It鈥檚 paying dividends now because with each of the four blocks, internal work has kicked off early. 鈥業鈥檇 put that down to the partnering philosophy,鈥� says Vernon.

Vernon suggests that if constructors could be brought on board even earlier 鈥� during the client-driven stage 鈥� the detail design process would be made considerably easier. 鈥楾he global philosophy for the structure and design was already set by BDP when we came on board and we then had to make all the elements work within that. We鈥檙e governed by a structure that says the frame is concrete, the roof sheet must work as a diaphragm, and all the fixings have got to suit a 140mm wide glulam. If we had more time during the client driven stage, we could make our own decisions about detail design.鈥� A pro-active, rather than reactive, approach, in other words.

Other hurdles include achieving air-leakage rates of 5m3 per hour (the latest Part L requirement, despite the building being designed before the new regs came into force), no mean feat with so many junctions between materials; keeping roof welding points out of view (meaning extra-long sheets rolled on site); and interfacing the ETFE pillows with the curved Kalzip standing seam system (a detail barely considered in the early stages).

The conical turrets are equally tricky but Lakesmere has a solution: it produced something similar for the Welsh Assembly building and has sourced a manufacturer within its own supply chain, evidence, for Vernon of the spirit on site.

鈥楿ntil you see the frame go up, there are details nobody will have thought about. Things like that can stop a job. But if you鈥檝e a good relationship in place, you can tackle anything.鈥� It鈥檚 more than a soundbite: Leigh Academy, despite its complex design, is both on time and on budget. And, as you can see from the pictures here, this is not a lacklustre box.