The long-awaited new National Structural Timber Specification (NSTS) document has now been published. The NSTS marks a significant step forward for the timber industry in levelling the playing field against competing materials such as steel and concrete.
Both the steel and concrete industries already have National Specification publications – in fact steel’s ‘black book’ is already into its fifth edition – but the timber industry has been slower in this area – until now. Hopefully the NSTS will make the specification of timber a simpler prospect for all sectors of the construction industry and provide a set of best practice guidelines against which timber buildings can be erected.
The brainchild of TRADA, the publication of the NSTS is not a small step forward but rather a giant leap. Working with industry specialists, TRADA has developed a recognised comprehensive specification that covers information exchange, materials, fabrication, erection, protection and quality assurance. It’s a real game-changer for an industry that has – to this point – relied on using documentation from previous projects to fit the latest one.
The NSTS focuses on structural uses of kiln-dried softwoods for use in three main areas – light-frame construction – usually known as ‘timber frame’. Heavy-frame construction – typically glulam and other engineered timber post and beam structures – as well as panel construction (typically cross-laminated timber and SIPS).
For each of these areas, methods of erection and tolerances are defined. It is conceivable that the specifier might choose to adopt a ‘different’ set of guidance and tolerances from that normally expected. The design of NSTS has deliberately followed Eurocode 5.
There has been no provision for BS 5268 because it has been withdrawn. In future editions, it will be possible to create further modules to cover non-structural uses of timber – joinery, decking, cladding and flooring. Another area for future consideration will be hybrid construction (where timber is combined structurally with other materials).
“New developments in engineered timber and computer controlled machining, mean that it is now the ideal material for rapid prefabrication and erection,” says Arup’s Andrew Lawrence. “A standard UK timber specification is a vital part of helping timber realise its potential as a standard construction material for larger buildings alongside steel and concrete.”This isn’t just a box-ticking exercise either, adds Rupert Scott, TRADA’s Membership Manager: “The consultation was opened up to all TRADA members and we’re delighted that nearly 100 individuals, with a passion for building with wood, have volunteered to provide valuable feedback.”
The development and quality of the NSTS is supported by a team of expert TRADA members. Nick Milestone of B&K Structures chaired the steering group, which included representatives from Kingspan, Arup and BM TRADA. Peer reviewing was provided by representatives from Smith and Wallwork, BAM Construct UK, Ramboll, Waugh Thistleton and NHBC, followed by a wider consultation among TRADA members.
“We believe that it will make a huge difference to timber by providing a very easy way for everyone to specify all the general aspects of structural timber by just referring to this free-to-download document,” says Rupert Scott, TRADA membership and marketing manager.
Visitors to Timber Expo will be able to hear a lot more about the NSTS and take part in a panel discussion during the TRADA-organised Timber Focus seminar sessions. At 11.00 Tuesday 6 October, Nick Milestone, Managing Director, B&K Structures; John Allen, Senior Engineer, MACE Construction and Alan Murray, Technical Author, RIBA Enterprises will introduce this new tool for the construction market and discuss its purpose, content, benefits, results of trials and relationship with NBS before inviting a panel and audience discussion on what could be done to make it easier to specify timber and what other guidance tools would make timber easier to specify.
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