Timber frame is steadily increasing its share of the UK house-building market where its ability to contain massive amounts of energy-saving thermal insulation combines with quick, cheap build cycles to win over developers and homeowners alike. The timber frame industry has long insisted that the system is also ideal for multistory apartment blocks, hotels and student halls of residence and several multi-storey timber frame buildings have been erected in the UK.
Even some commercial buildings have exploited timber frame’s speed of erection and its potential for innovation in design and sustainability.
But nobody’s seriously suggested using timber frame for large industrial buildings… until now.
Contractor Clugston Construction recently completed the erection of what is claimed to be one of the largest timber-framed buildings in Europe and the largest ever erected in the UK.
The building will house a new energyfrom- waste plant which to be operated by French firm Veolia Environmental Services under a PFI contract with Leeds City Council. The facility, located on the Cross Green Industrial Estate, is intended to provide Leeds with a long-term solution to divert waste away from landfill. Up to 214,000 tonnes of the city’s black-bin waste will go through the facility each year.
Recyclable materials will be removed for reprocessing and the remainder will be incinerated in a process that is expected to generate enough electricity to power up to 20,000 homes.
The development comprises three buildings, all timber-framed. In one of them, recyclable materials will be mechanically separated while, in the neighbouring building, up to 164,000 tonnes of unreclyclable waste will be burned every year to generate electricity.
The third building is a domed structure which will be used to store fuel ash from the incineration plant.
The facility has been designed by French architect Jean-Robert Mazaud of Paris-based Space Architects; another French firm, renewable energy engineering specialist CNIM, has designed, and will install, the processing plant.
“Timber was chosen by the client to reflect the sustainable nature of the project,” says Clugston Construction director Paul Gouland. “They, along with our client Veolia, were therefore keen to champion the use of materials from sustainable sources and use it dramatically to highlight the point.”
The client was also keen to create a prominent landmark. The new buildings will be visible to people as they draw close to Leeds city centre via a recently-completed link road off the A1M to the south-east of the city. The new facility is the first major building to commence on the Aire Valley Redevelopment Zone.
Construction work started in October 2013 and completion is scheduled for mid-2016. Leeds City Council has estimated that, as an alternative to sending waste to landfill, the facility will not only benefit the environment but will save as much as £200m over the next 25 years.
The load-bearing frame of the mechanical pre-treatment hall is 18m high, 123.5m long and 36m wide and made of glue-laminated timber – or glulam - throughout. The building will be clad with a transparent shell of polycarbonate panels designed to flood the inside of the building with daylight.
The main energy-recovery facility building, at 42m in height, 130m in length and 36m in width, is believed to be the largest timberframe building yet erected in the UK. The main structure comprises 20 massive timber frames incorporating glulam arches spaced at 6.5m centres. The building is designed so that the structure will be visible throughout its entire length.
Along one elevation is a living “green wall” – believed to be one of the largest in Europe - while the building’s eastern elevation will feature a viewing gallery clad with a timberand- glass curtain wall.
The ash storage building is a timber-framed half-dome, 12m in height, supported by arched glulam beams and timber cladding. German glulam manufacturer Hess Timber manufactured the timber components in Germany and transported them in sections weighing up to 19 tonnes each via road and ship to Immingham Docks on the Humber. The components were assembled on site before being craned into position by the Hess team. The need to find a glulam supplier with the technology and capacity to produce structural beams of this size and in this volume inevitably took the search to mainland Europe, says Gouland:
“Hess was selected because, after discussions with other possible suppliers, they were the only ones able - at that stage, anyway - to handle the size of frame required”.
Hess also had a solid track record, having delivered other major schemes such as the D1 Tower in Dubai and the museum of the Louis Vuitton Foundation in Paris.
“This was a major new area of experience for us,” continues Gouland. “The main challenge of working with timber was simply the fact it wasn’t steel like all our previous projects. From a design aspect the structural loadings were complex and took some time to understand as we are more used to designing steel structures.”
On the other hand, installation of the frame components is very similar to steel, says Gouland. “It has run well to date. The original plan had been to drop just one unit into position on the first day but as it went smoothly two were positioned before the day was out.” Some might question the wisdom of building a major incineration plant out of timber – especially given the fact that at least two major timber-frame developments have been destroyed mid-construction in recent years.
However, while poor site practice might render timber frame vulnerable to fire during the construction phase, once completed it is no more prone to fire than any other building method. Every building – no matter what materials are used – must conform to the same fire regulations.
Furthermore, says Gouland, “laminated timber beams are recognised in technical studies as having good structural integrity in regards to fire performance. “Design-wise the incinerator section is situated in the main boiler structure and in a sealed environment. Like all the other energy- recovery schemes there are also advanced detection and suppression systems throughout the receiving and processing buildings,” he adds.
This article first appeared in the October 2014 issue of The Construction Index magazine. To read the full magazine online, click here.
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