Summary
¦ Energy requirements will help drive demand for timber components.
¦ The versatility of engineered timber systems makes them suitable for any sized project.
¦ James Jones supplies glulam for housebuilding.
¦ KLH has completed about five houses in cross-laminated timber this year.
¦ The latest Wood Talks seminar was sponsored by B&K Structures.
Engineered timber is no longer a novelty in the housebuilding industry but, as James Sweet, director of construction consultancy C4Ci, points out, little more than a decade ago products such as timber I-joists were considered new and unusual.
These “new” components promised huge improvements in efficiency and productivity for housebuilders, and in performance.
“The growth in timber frame construction – not just for single family houses but also for multi-occupancy buildings and light commercial structures – has led to further innovations in engineered timber technology,” said Mr Sweet.
“I-joists are now being used not only in floors, but in wall and roof cassettes where their depth allows high levels of insulation to be incorporated. Companies are developing sophisticated wall and roof systems, joining studs together with metal sections to create depth at optimum cost.”
Tighter regulations
The Code for Sustainable Homes and tightening of Part L of the Building Regulations have also fuelled housebuilders’ interest in engineered solutions, in particular the metal-web joist.
“Thermally-efficient airtight buildings should be mechanically ventilated. This increases the M&E and ductwork within the floor zone,” said Mr Sweet. “Though timber I-joist systems are generally more cost-effective than open web joists per metre, system owners and their suppliers will need to find ways of providing the service holes to accommodate this new demand on or off site.”
And, he added, innovations in engineered beam systems meant they were well positioned for growth once the economy, and housebuilding, picked up.
Finnforest’s engineered timber products, such as Kerto LVL, are equally at home in an energy-efficient supermarket or a residential property.
“Because of the versatility of engineered timber systems, they are well suited to smaller residential projects,” said Kevin Riley, Finnforest’s vice-president construction industry.
Its low energy system, which features the engineered Finnjoist, was recently specified for a self-build eco-house in Wales. “The architect, Michael Goulden, specified the wall and roof systems for their energy-efficient performance and the inherent environmental credentials of the timber itself,” said Mr Riley.
Engineered timber wall, floor and roof sections will also help housebuilders meet the more stringent requirements of the updated Part L as they offer deeper sections, and therefore more insulation.
“Engineered timber products can have a significant influence on the fabric of the building,” said Steico sales manager Adrian Judd. “This core element should be seen as more than just the physical load bearer and control for the shape of the building. It should also form an integral part of the insulation envelope which is increasingly important in determining the energy efficiency and healthy internal climate of the finished building.”
And while there has been a resurgence in timber frame, engineered timber products such as I-joists can be used across the range of build methods, he said.
Glulam
The amount of glulam used in housebuilding may be small compared with other timber products, but for James Jones & Sons’ Timber Systems Division it’s an important market.
The company supplies glulam from Austrian manufacturer Binder to the housebuilding market through its UK-wide distribution network – GL24, specifically for rim beams, and the higher quality GL32 grade for intermediate load-bearing beams.
“Our housebuilding customers are both in timber frame and masonry but by far the larger market is timber frame,” said Brian Robertson, Timber Systems Division general manager.
“Our level of supply is directly tied to activity in the housebuilding market so, like everything else, volumes have suffered recently. That said, currently we have clients to whom we supply glulam stretching from the north of Scotland to Southampton. While the volume of glulam we supply to individual jobs may be small – sometimes only two or three pieces – all of our jobs incorporate some volume of glulam, so that’s significant.”
Cross-laminated timber
At the heavy-duty end of the engineered timber products spectrum, cross-laminated timber (CLT) has been used as the structural element in UK houses. However, Craig Liddell, commercial director for KLH UK, which has supplied some high-profile projects such as the eight-storey Stadthaus in Hackney, the world’s tallest timber residential building, and Norwich Open Academy, thinks its future in housebuilding is in four- to seven-storey flat developments. A large part of the appeal, he believes, will be the product’s fire performance.
The company’s focus does tend to be large buildings but it has supplied CLT for individual houses, and in the past year it was involved in five house projects – “more than we’ve ever done”, said Mr Liddell.
They tend to be architect-designed houses and people have turned to the product for the design freedom and large spans it offers, as well as its sustainability credentials.
However, he believes we’re unlikely to see CLT being taken up by the mass housing market as more traditional timber frame methods are cheaper.
Award-winning design
Mole Architects chose KLH’s cross-laminated timber for a private house in Cambridge, which was joint winner of the Small House of the Year category in The Daily Telegraph British Homes Awards.
The practice specified the product for several reasons including the aesthetics, its environmental credentials (it is naturally insulating and boasts low embodied energy and high embedded CO2), and its acoustic properties.
“I do see the potential for increasing the use of CLT,” said architect Meredith Bowles. “Besides its structural and environmental advantages, it also has sculptural possibilities we’d like to make more of.”
