Town... or country?

Town

Situated next to a viaduct supporting Worcester’s mainline train station, with a post office access road running along one side and a busy A-road crossing its eastern facade, the Sansome Walk building couldn’t be in a more urban location if it tried. It’s strange, then, that main contractor Markey Construction opted for modular construction, as this usually requires large areas of space.

Built for developer Severn Vale Housing, which will lease it to the University of Worcester under a nominations agreement, the building comprises 83 bedroom ‘pods’ and associated shared kitchen/common room areas, each prefabricated off-site, delivered using a just-in-time (JIT) delivery method and positioned by crane.

‘When we arrived here the odds seemed to be stacked against us, the site was so tight,’ confesses Markey Construction’s head of student projects Andy Barham. ‘Every time we thought we had a solution for some aspect we realised we were encroaching on something else.’

The contractor got round this by building the block in three phases and using a neighbour’s drive (destroyed during work and subsequently rebuilt) to position the 200-tonne crane.

It’s no coincidence that modular was chosen for this job. Barham is also head of modular solutions at Markey and this scheme is a pilot project for the firm’s planned future expansion into modular construction.

‘In this country people tend to think of modern methods of construction (MMC) as restrictive because you need a big open site for the cranes and a perfect square building,’ he says. ‘But it’s not, you just have to be creative with how you design and erect your building.’

At Worcester there are obvious reasons for going modular. With the 2 September completion date looming the team needed a fast programme to get the students in on time to allow the university to start generating rent. It also meant Markey could quickly free up labour for use on other projects.

‘In an industry experiencing lower valuations and with finance costs going through the roof, getting the job done quickly means a faster return on investment, which will drive the industry going forward,’ says Barham. ‘The building wouldn’t have opened in time if we’d done it using just traditional techniques. We’d have needed another 36 weeks on the programme at least.’

After some complications with underpinning the viaduct, the foundations were completed in May. Remarkably, it then took just 12 days to erect the five-storey steel portal frame and fit all the modules. These were delivered by a Dutch company, Formula Bau, whose team worked alongside Markey during installation.

Each 14.7m2 prefabricated bedroom module comes fitted with a fully finished shower pod, a concrete floor, first fix electrics, plasterboard walls with a bottom coat of paint and skirting boards. Windows had to be fitted on site because delivery to the Dutch factory wasn’t possible before the pods were prefabricated.

The process of works for installing each module is as follows: four upright steel columns are erected, the module is lowered into position, then two steel cross braces are fitted on top. The modules are completely freestanding within the frame with just an eighth of an inch tolerance from the steel frame on either side.

The post office access road running along the side of the block was in regular use so JIT deliveries had to be intricately planned. ‘If there’s one thing I’ve learnt on this job it’s that pre-planning is so important with modular construction,’ says Barham. ‘The build itself happens so quickly you have to ensure everything’s programmed in exactly. For example, we’d have a module dropped off at say 10.15am, it would be fitted at 10.20am, then at 10.45am the next one would arrive.’

With the modules in place, the next challenge was the fit-out and finalising the exterior. ‘I specialise in inner-city projects, but this could have been a lot simpler,’ says site manager Dennis Perks. ‘I’m responsible for everything connected with the outside walls. The planners were insistent on using traditional brick cladding, much of Worcester is red brick, and we had to integrate that with the architect’s choice of modern cladding – seven types in total.’

What’s more, much of the modern cladding is rainscreen, which unlike the brick, did not completely enclose the pods, so extra protection works, flashing and damp-proof course works had to be completed to ensure water tightness before the cladding could go on. Because the pods are freestanding and not bolted to the frame this also put extra pressure on the installers to get the positioning just right because any inaccuracy would have affected the positioning of the cladding.

Despite some early problems Barham is happy with progress at Sansome Walk and is already lining up Markey’s next modular job in Gloucester, this one to incorporate a more complete modular solution. ‘The upfront cost of MMC may be more, but you can reflect that in your negotiations with the client. From their perspective they get their rent a lot earlier and with labour freed up earlier you could do two jobs a year instead of one. What’s more, we’re a chartered building company and we firmly believe we’re doing the right thing by embracing new technologies like MMC.’

Urban Project

Sansome Walk, Worcester

Spec: 83-bed undergraduate student accommodation block

Client: Severn Vale Housing

End user: University of Worcester

Architect: BM3

Main contractor: Markey Construction

Build cost: £3.6m

Timeline: September 2007- September 2008

The Sansome Walk building comprises 83 bedroom ‘pods’, each one fabricated off site and delivered just-in-time

Country

There were delays. during the winter it got really windy on the hill.

Perched atop a verdant green hill in hundreds of acres of grounds overlooking the cathedral city of Canterbury, the University of Kent campus is perfectly positioned to develop a new college. Or so you might think. Strict planning laws have prevented University Partnerships Programme (UPP), the developer of Virginia Woolf College, from encroaching onto the grassland that slopes down towards the city and forced it to utilise a site to the rear of the campus on a road and bordering woodland.

Built by Mansell for UPP, which is financing the project and will manage the buildings for the university post-completion, the development comprises eight post-graduate student accommodation blocks, an ‘enhanced’ accommodation block, an academic building and a lecture theatre.

‘Canterbury was one of our most difficult sites in terms of accommodating planners’ wishes against what our architects wanted to do,’ says UPP product development manager Bob Giles. ‘We had plans to clad the buildings in brick, which they wouldn’t allow, probably because most of the existing stock is clad in blockwork.’

Architect David Morley’s plans to position plant rooms incorporating solar panels on the roof were also quashed because planners ruled that the buildings couldn’t protrude above the tree line. And intentions to clad the lecture theatre block in zinc were point blank refused over fears that it would resemble a gasometer.

‘They see the campus as being very much like a little village and are very insular in terms of what materials they want to see here,’ says John Morley, the university’s head of capital projects. ‘The university has been here for 40 years in landscaped grounds and the planning officer, supported by the client committee, wanted to keep it that way, so we struggled a bit.’

Mansell arrived on site in August 2007 and with the September 2008 deadline a year away, it was eager to get started. But at that stage the project hadn’t even reached financial close, and while most of the packages were finalised, designs were still fluctuating and a value engineering exercise was under way as the team tried to reduce the original £30m build cost. This turned out to be an important exercise, trimming down the ‘nice to haves’, changing material specifications and simplifying foundation solutions.

‘The materials selected had to have a certain life cycle so they only get replaced or maintained so many times during the lease period, which we had to be aware of going into the value engineering process,’ says James Knowlton, senior project manager at Mansell. In total the team shaved £4m off the original cost and managed to fit an extra 10 bedrooms into the design.

When construction began, variations in ground conditions meant using a combination of piling, deep strip and slab foundations. Four frame types were also selected to match the building uses – a standard timber frame for the four-storey student blocks, a more complicated timber frame for the five-storey enhanced accommodation block, an exposed reinforced concrete frame for the adjoining academic building and a steel frame for the curved lecture theatre block.

‘The enhanced student block, academic block and lecture theatre are all conjoined, so marrying the timber, concrete and steel frames together took a lot of pre-design work and initially we weren’t too sure about the concrete/steel interface,’ says Kevin Atkinson, construction director at Mansell. ‘It took a lot of detailing, design meetings and discussions with consultants and specialist contractors.’

With students due to move in in September, Mansell opted for a fast-to-erect timber frame solution in the accommodation blocks, with cassettised floors, panellised walls and modularised en-suite bathroom pods. It took four weeks to erect each building and a total of eight weeks to make each one watertight.

‘There were some delays because we’re on a headland, so during winter it got really windy on the hill. We had a mixture of mobile and tower cranes, none of which could work all the time,’ says Knowlton.

A big challenge was getting the bathroom pods to site on time as work proceeded. ‘To keep the programme running we had to make sure our JIT deliveries arrived on time because we couldn’t place the next floor slab on top of the walls until the pods were in,’ says Morley. Space was also an issue because acoustic and fire protection requirements meant simultaneously installing several layers of plasterboard and acoustic flooring while trying to position the pods. ‘The frame goes up fairly rapidly so you can’t afford to lose even half a day between finishing your timber frame walls before dropping the pods in,’ adds Atkinson.

The plasterboard posed another logistical challenge. Each bedroom has 35 sheets of it, all double layered, which meant a large amount of waste. Mansell invested in a chipping machine to reduce the amount of skips on site and free up some space.

At Virginia Woolf they are aiming for a ‘very good’ BREEAM rating. ‘In several key areas, airtightness for example, we set the goal to be 20% better than Building Regulations,’ says Giles.

Mansell has three handover deadlines for the college, 15 September for the 450 residential units, late October for the 91 enhanced units, and 1 December for the academic building and lecture theatre. When CM visited the site in July the team was just a week adrift of its programme.

Campus Project

Virginia Woolf college, Canterbury

Spec: 450-bed post-graduate accommodation in eight blocks, 91-bed ‘enhanced’ accommodation block, academic building and lecture theatre block

Client: University Partnerships Programme

End user: University of Kent

Architect: David Morley Architects

Main contractor: Mansell

Build cost: £26m

Timeline: August 2007 – September 2008

Planners wanted Virginia Woolf College constructed from blockwork rather than brick and wouldn’t allow plant rooms on the roof, as these may have spoiled the aesthetic appeal of the campus

 cm