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‘Just hold on tight because it’s windy and there’s just 1.2 millimetres of perforated steel between you and the concrete floor 22m below.’ These are my thoughts as I stand atop the huge domed roof being erected on Monkseaton High School in North Tyneside. The slippery metal sheeting that curves steeply down towards a lightweight perimeter handrail looks dangerously like a ski slope, and the bacon sandwich I had for breakfast no longer seems like such a good idea.

Located a few miles from the resort town of Whitley Bay, the school sits in an expanse of playing fields like a glistening new sports stadium. It’s a dramatic presence in an area of grassland bordered by residential streets, which is firing the imaginations of children in the adjacent school who will soon make it home.

Inside, the roof envelops the entire footprint of the school like Wembley Stadium and I feel a sudden rush like I’m David Beckham on cup final day. When the building is completed in September, the exposed white-painted trusses and purlins, and the perforated soffit, will all be on view from the various open learning spaces, central sports hall and ceilingless classrooms.

Monkseaton is a visionary blueprint for a 21st century secondary school, and is based on one of six secondary school concept designs produced for the Department for Education and Schools in 2004. Elliptical in plan, the roof curves in two directions, a form that posed significant design challenges for architect Dewjoc and structural engineer Parsons Brinckerhoff, while main contractor Shepherd Construction had to search far and wide to find a specialist willing to build it.

North Tyneside Council and Monkseaton’s head teacher, Paul Kelly, were committed to implementing the exemplar project, having worked on it in 2004 with concept architect de Rijke Marsh Morgan (DRMM). But with a meagre £21m to play with and the concept drawings depicting a giant transparent ETFE bubble covering reconfigurable classrooms, something had to give.

Once Dewjoc was appointed in 2005 following the allocation of funds through the government’s Targeted Capital Fund, it became a case of visionary architecture meets pragmatic value engineering. The ETFE and timber gridshell was transmuted into a steel frame with bulbous brise soleil walls, roofed by an aluminium dome punctured by ventilation flues and large roof lights to maximise daylight.

‘We’d have really liked to have retained the gridshell, but that was prohibitively expensive,’ says Ian Lancastle-Smith, director of Dewjoc. ‘Besides, during the design process I was at the Eden Project in Cornwall. It was raining and the ETFE was making a hell of a racket.

I phoned the head teacher on my mobile, and said: “Listen to this, it’s 120 decibels in here, we can’t build one of these!”’

The roof is supported on 11 giant hollow-section bow string trusses that rest on steel columns, enabling spans of up to 45m and creating an uninterrupted space for the central sports hall. These are laid with steel purlins and covered with perforated liner sheets – the slippery ones that disagreed with my bacon sandwich. The roof covering is a standing seam system, chosen by the design team to withstand the harsh coastal climate.

The standing seam is punctured by seven Xtralite triple-glazed rooflights, which vary in size from 11m x 6m to 35m x 6m, and should flood the interior with daylight. Kelly wanted a minimum of 1,000 lux, a figure scientifically proven to improve teenagers ability to learn (see panel overleaf). Daylight modelling showed that this design, which also includes bands of windows around the external walls, would be at least equal to the daylight levels afforded by the original ETFE design.

The roof lights are filled with nano-gel, a very thermally efficient gel which diffuses light to reduce glare as well as creating a clear blue-tinged northerly light regardless of the sun’s position in the sky. On darker days interior light levels will be boosted by lamps suspended from the roof.

Puncturing the curved roofline are 31 ‘wind catchers’, supplied by ventilation specialist E-Stack, which are designed to reduce the building’s reliance on air conditioning by encouraging air movement. These domed structures incorporate low-power 40W fans, which in the summer draw in cool air from outside and suck hot air out from the roof to stabilise temperatures at 18-20°C.

The system is part of a passive thermal heating and cooling strategy that includes solar shading from brise soleil on the exterior walls, high levels of insulation and what Lancastle-Smith terms ‘kid-o-watts’ – using heat generated by the school’s 900 plus children as part of the overall heating requirement.

Setting out the spacer system for each standing seam was critical

Chris Hendrick, Keyclad

Installation of the roof began with the giant trusses, each of which were delivered to site in three sections and bolted together on the floor. Shepherd site manager John Butterworth used two 50-tonne remote-controlled mobile cranes, one on each side of the building, to hoist each truss into position.

The steel trusses and other members were supplied and installed by Bridlington-based Pocklington Steel. More familiar with building car showrooms, Pocklington was one of the few companies willing to manufacture the huge number of hollow sections required for the building’s structural frame and roof – more than 7,000 steel components weighing a total of 950 tonnes.

Once Pocklington had bolted the tubular steel purlins to cleats welded into the trusses, a team of 30 operatives from roofing specialist Keyclad began work on the standing seam system. ‘Saddles’ were first fixed on top of each of the purlins to create a flat surface to fix the perforated liner sheets to. A Keybar spacer system and halter clips, manufactured by Keyclad’s sister company KeyBemo, was fixed to the liner sheet to provide support for the aluminium top sheet.

A 30mm layer of thick, white tissue-faced Rockwool was then laid on top of the liner sheet to provide acoustic insulation, then covered by a Monaflex vapour control layer. A further two layers of 100mm Rockwool insulation were laid over this. Finally, the 0.9mm-thick KeyBemo standing seam top sheet, finished with stucco-embossed aluminium, was fixed to the spacer system.

Although Keyclad has completed similar roof installations, notably for the new grandstand at the Oval cricket ground, the sheer scale of this job pushed it outside its comfort zone. ‘It’s very, very demanding and complicated up there. The logistics of getting men and materials onto the roof has been a nightmare and we underestimated the time it would take,’ says Keyclad’s site manager Chris Hendrick.

Dewjoc’s Lancastle-Smith compares the installation to a ‘dress-making’ exercise as workers manoeuvre around the numerous penetrations for roof lights, wind catchers and other services.

Hendrick agrees: ‘The lads have been getting frustrated and having to continually stop and start, they’re used to running entire sheets from gutter to gutter. We had to do a lot of work on the geometry before we hit site, setting out the spacer system for each standing seam was critical because the roof curves in both axes and the sheets naturally want to banana.’

To accommodate the domed shape, a series of tapered 12m-long top sheets will be inserted at intervals between sections of parallel sheeting. Although these were anticipated in Keyclad’s 3D model, the actual number of tapered sheets and dimensions will be a more ad-hoc affair altered on site.

The domed shape also created problems when manufacturing the top sheets. The aluminium is delivered to site on a large coil, which is run through a roll forming machine to create the sheet profile. When building a typical roof, the roll former spits out the sheets straight onto the structure at eaves level. But the height of the dome at Monkseaton would have meant elevating the machine four metres above the eaves, and erecting a scaffold platform on the roof structure.

‘It was impractical to say the least, so we decided to split the sheets into three lengths, the longest are 26m, roll them out at ground level and then crane them up in two batches, one for each phase of the roof,’ says Hendrick.

Despite the various setbacks, work on the roof is due for completion to programme early this month, and Shepherd is due to complete the overall project by 25 September.

With so many boxy and uninspiring new secondary schools being built, Monkseaton’s innovative design is refreshing. Although there have been compromises to the original design, it will still satisfy both the cash-strapped council and future-focused educationalists.

‘Radical and replicable is my new mantra,’ says headmaster Paul Kelly. ‘We will have built an innovative design for less cash than the average school in just 69 weeks. It makes me wonder why more councils haven’t taken up the exemplars.’ After a trip to Monkseaton, CM is wondering that too.