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A study in timber
Autumn 2008
Published:  01 December, 2008

Provian Construction has been working hard over the long summer vac to provide a home-away-from-home for students at the University of Greenwich. Sally Spencer reports

The Michaelmas term is now well under way and for 144 lucky students at the University of Greenwich’s Medway campus, the living – if not the studying – is easy.
They’re the first residents in three new accommodation blocks in the top corner of the campus which was once part of Chatham Historic Dockyard.
A Medway Council-approved planning scheme was already in place when Provian Construction was awarded the £5m contract. Long-term partner GDM Architects also came on board and their first challenge was to find a building system that would allow them to complete the project during the summer vacation. 
“The brief was to construct 144 student bedrooms and associated living rooms/kitchens over three blocks,” said project architect Kevin Matthews. “We also had to provide a house for the warden who will manage these three blocks, along with two existing facilities, and a laundry.
“Time was the biggest issue as we had to be able to accommodate the students for the next academic year, so we needed a system of building that was going to give us the quickest erection of superstructure on an economic basis.”
GDM and Provian looked at both metal and timber frame and concluded that the latter had the advantage “both financially and in programme”.
The next challenge was the size of the site – a very compact 3,300m2 footprint, with some height restrictions – and the need to blend the planning authority’s preferred contemporary design with the naval heritage architecture of other parts of the campus. The use of sustainable materials was also a prerequisite.
“Although there was no requirement for a BREEAM assessment to be carried out, part of the design objective on the part of the client was that it incorporated aspects of sustainability,” said Rick Archer, Provian’s design and build co-ordinator. “That’s partly why we went for timber frame.”
Each of the three blocks comprises four storeys of timber frame on piled foundations. Each floor comprises two flats and each flat consists of six study bedrooms feeding off a central corridor, with a communal kitchen/living area at the end. From the exterior, featuring floor to ceiling height glazing and low maintenance shiplap cedar cladding, these communal areas make a strong design statement.
“The original plans indicated that there may be elements of steel in these communal areas and that the steel work would be exposed, but by opting for timber frame early on, we were able to adapt the design and deal with those elements in a different way,” said Archer. As a result of the tweaks, sections of decorative “umbra grey” Rockclad Rockpanels, fixed by softwood battens to the exterior of the frame, give the impression of steel girders framing the floors here.
There were other less cosmetic benefits, too. If the kitchen end consisted of horizontal and vertical steel members while the main box of the building was timber frame, differential movement would create an ongoing maintenance issue – and low or no maintenance was another planning authority specification.
The timber frames were manufactured by Margate-based Roe Timber Frame on a just in time basis and transported to site, where the blocks were erected sequentially. This programming enabled Provian to provide a waterproof environment to allow the rest of the trades to continue through the wet summer.
Roe Timber Frame also supplied 18mm OSB panels, complete with breather membrane attached and open to the inside, allowing 75mm Crown wool insulation, 500mm gauge polythene vapour barrier and two 12.5mm Fireline boards to be added on site.
The exterior face of the OSB panels in the main body of the buildings was coated in waterproof render – again, on site. “Marmorit Warm Wall render system was used: this consists of a mineral fibre external wall insulation finished off with the breathable render,” said Archer. “The insulation and render all come as part of the package.”
The Warm Wall render system, along with the insulation within the panels, enabled Provian to reduce U-values from 0.35W/m2/K to 0.3W/m2/K.
The panels were lifted into position by crane and fixed to the frame. As each storey went up, ensuite bathroom pods were installed in each bedroom before the floor of the next level went on. These French-built glass fibre “Calypseau” pods, supplied by Baudet UK, comprise a shower, hand basin and lavatory and fit neatly into the corner of each bedroom. Each pod arrived pre-plumbed leaving on-site electricians and plumbers to make straightforward connections. All that remained then was plasterboarding around the pod.
Maintenance access is through a panel from the central corridor, although, as with the rest of the buildings’ materials and components, the pods are designed for durability.
Student-proofing is one thing, student sound-proofing is quite another. “Student accommodation is treated under the regulations much the same as any other residential apartment block,” said Matthews, “but the difference is that each wall between bedrooms is treated as a separating wall between flats would be.”
Sound attenuation had to be achieved between the rooms and between floors and advice was sought from acoustics specialist BTP Hyder. “The main method was to use a resilient bar system for the ceilings [16mm British Gypsum RB1], the wall voids were fully filled with acoustic insulation and we used an acoustic floating floor,” said Archer.
The floor of choice was 36mm ElecoFloor, a composite panel acoustic floating floor system that is laid onto decking boards, which are fixed to floor joists in the usual manner. The upper surface of ElecoFloor is a traditional moisture resistant tongue and grooved chipboard over three more layers of sheet material. This provides the density to absorb airborne sound and the damping to minimise the transmission of impact sound.
“We used the resilient bar on top of the ceiling finish and each of the walls,” continued Archer. “The design of it is such that the walls are acoustically separated from the element above, so that, although the line of structure runs through the building, the actual finishes are separated from those structural elements and we achieve acoustic separation between floors and walls – it’s all down to the detailing.”
Incorporating super soundproofing had the advantage of adding fire protection measures in one fell swoop, but threw up another challenge – that of routing services without compromising any of the acoustic partitions by passing through them. And services there are in abundance – in addition to heating and water pipes and electrical cabling, there are datacoms for internet access and ensuite mini-fridges to be considered.
Although the wall between the bedrooms and the central corridor is acoustically treated, it is not deemed to be an acoustic wall, so the solution was to use the ceiling void above the corridor as a service route, feeding into each unit from a high level. Sockets within the units are all surface mounted on trunking, to avoid penetrating the acoustic walls.
A continuously flowing venting system feeding from all the Calypseau bathroom pods into the ventilation plant room in the roof void also ensures the integrity of the acoustic separation remains intact.