• Cross-laminated timber was used in the world’s tallest timber residential building.
• Engineered timber can help meet architectural and technical challenges.
Finnforest‘s Kerto is being used in two projects in London this summer.
Timbmet has two new engineered products.
• Ante-Holz’s recent investment could result in more KVH coming to the UK.

A new world record was set in March this year when a nine-storey apartment block – the tallest timber residential building in the world – was completed in Hackney.

While it was a showcase for the literal and metaphorical heights that timber has reached, it was also further evidence of the benefits of engineered timber and its growing acceptance among architects, specifiers and developers.

The brainchild of architects Waugh Thistleton, the 29-apartment Murray Grove Tower was commissioned by housebuilder Telford Homes and was constructed using cross-laminated timber panels from Austrian company KLH.

Each of the timber panels was prefabricated, including cut-outs for windows and doors. As the panels arrived on site, they were craned into position, dramatically reducing the time on site. The entire nine-storey structure was built within nine weeks.

While Craig Liddell, KLH UK senior representative, admits that there haven’t been any developments in the product per se, the real progression has been in timber engineering – as evidenced by the Murray Grove Tower development. “It’s really pushing the boundaries of the product,” he said. “We’re going taller than timber has gone in the UK and, as far as we know, even across Europe.”

Further evidence of the growth of engineered timber is its use in education establishments. KLH UK recently supplied material for a classroom block and sports hall at the St John Fisher School in Peterborough which, in terms of timber volume, was actually bigger than Murray Grove. “It was a very sustainable engineering solution,” said Mr Liddell. “But it was the structural capabilities of the product which were the biggest factor.”

Architectural and technical challenges

Certainly, engineered timber is being used to rise to architectural and technical challenges. For example, because of the strength-to-weight ratio that Finnforest’s Kerto affords, architects are able to create seamless roof decks with no visible joints. Similarly this means that wide spans can be achieved, where perhaps timber would not have been considered in the past.

Two architectural ‘installations’ are currently raising the profile of Kerto in London: The Architectural Association’s summer Pavilion, The Swoosh, in Bedford Square, and artist Toby Patterson’s installation in Potters’ Field Park on the South Bank for Portavilion.

Mr Patterson was particularly enthusiastic about the material, which he chose because of its “versatility, inherent strength and the ease with which it can be cut and assembled”.

Finnforest head of marketing Warren Dudding said supporting such structures enabled Finnforest to provide architects with the chance to experience designing with engineered timber first hand.

“Engineered timber products have almost limitless applications and huge flexibility and these projects show the diverse and ambitious effects that can be achieved and, we hope, will inspire architects,” he said.

Aesthetics is obviously key, but if the products don’t perform, their use will be limited. Timbmet’s Justin Hayward believes that “customers want a product that does what it says on the tin”, particularly when it comes to performance. The company has been developing its involvement in both engineered and modified wood and has unveiled Thermally Modified Timber, spruce and beech heat-treated to improve durability. It has also introduced Air-o-Therm, a window scantling with air chamber systems that promises to combine “energy-saving environmental benefits and affordability”.

Structural insulated panels

Structural insulated panels, or SIPs, are another engineered product category showing strong growth. Among the rising number of companies focusing on the sector is Palgrave Brown, a licensed fabricator of Kingspan TEK SIPs which comprise twin panels of OSB, bonded to a CFC/HCFC-free rigid urethane insulation core. Panels are factory cut to size prior to delivery and fit together exactly, so time on site is minimised through extremely fast build times, improving cash flow.

“What’s more, they exceed current Building Regulations, being highly thermally efficient, extremely airtight and with very low sound transfer properties,” said commercial director Mike Fleming. A Palgrave Brown project using Kingspan TEK, he added, recently won the Kingspan Project of the Year Award and he believes more architects are waking up to the structural and sustainability advantages that engineered products offer. And Palgrave Brown believes the sector could get a further boost from the London 2012 Olympics, where prefabricated construction is expected to play a major role. “We are seeing a general growth in offsite construction methods and SIPs fit ideally with this trend,” said Mr Fleming.

The most prolific engineered product in the UK, the I-joist, also shows no sign of slowing down in terms of market penetration. New players are entering the arena and annual sales are now around 20 million linear metres.

And underlining the growing maturity of the UK engineered wood business, still more new products are coming onto the market. One that is long-established in Germany and now making headway here is KVH (Konstruktions Vollholz). This is a solid structural timber, comprising finger-jointed softwood produced by licensed manufacturers to a specific formula to give superior stability over long lengths. It is also used in two and three layer laminated form (Duo and Trio).

The material has 40% of the German constructional timber market and suppliers are looking for it to repeat its success in the UK. A producer in the forefront of this marketing push is Ante-Holz, one of Germany’s biggest mills and a company with an established presence in the UK. It recently completed a new 200,000m³ capacity KVH mill, taking its total capacity to 350,000m³, which is expected to lead to it targeting more product to its export markets.