Steeling the show with glulam

If glulam is to conquer the market for large-span structures, it might have to look to its competitor for help. TiC reports.

THE RATHER catchy glued laminated timber, or glulam, may soon have to take on another guise, if Bowmer and Kirkland gets its way.

Last year it added a timber structures division to its 20-plus groups specialising in glulam and steel hybrids.

The new division, appropriately named B&K Timber Structures (B&KTS), has already carried out large contracts for retail heavyweights, Asda and Sainsbury’s, and is firing on all low-carbon cylinders to deliver more than £4m turnover this year.

Traditionally the two materials have been used in competition; glulam chipping away at steel’s dominance for large span structures in the industrial, retail and education sectors.

It owes its growth to the government’s drive for sustainability, as glulam is renewable, has a low embodied energy and, aesthetically, sits into an environment much better than grey and dreary metal.

Steel has had the market dominance for large sheds and retail outlets. However, laced with gargantuan demand from the Far East, and the rising cost of Iron Ore, steel has been a volatile and unpredictable material to specify in recent years.

B&KTS is in the best possible position to assess a future market for a steel and timber hybrid. Its £20m-a-year steelwork fabrications group has carried out steel frame construction for the same market it aims to target with the steel and timber hybrid.

“The demand is predominantly coming from retail, purely because of their approach to sustainability,” says construction director, Nick Milestone.

Corporate Social Responsibility Programmes and the government’s drive toward sustainable building targets have made retailers environmentally conscious over their building programmes.

Technical with timber
B&KTS was set up in January 2007 and this year expects turnover to be approximately £4.25m. “We estimated between £3m and £4m,” says Milestone, “so we’ve achieved our expectations.”

Milestone explains that the new outfit has brought in personnel from timber engineering backgrounds and has combined that with the group’s structural steel staff to create a workforce of 50.

B&KTS partners with glulam manufacturers in Germany and Austria and generates 3D models of the structure with the connection parts in steel. “Using 3D modeling initiatives that we use in structural steelwork,” says Milestone, “We’ve developed our software to accommodate German and Austrian CNC (automated manufacturing procedures) post processing.”

It issues the German and Austrian manufacturers with full-scale drawings. They then convert the drawings using CNC machinery, which automatically drills, cuts and slots the timber to precise dimensions. When the glulam comes to site it then fits the steel connection plates.

“We then project manage design co-ordinate and manufacture the steel component parts in parallel with the glulam manufacturer,” says Milestone. “So when it comes to site, we then sub-assemble the items and erect the structures.”

Milestone claims B&KTS is one of the first contractors to use 3D technology to supplement the CNC technology of the UK’s European counterparts.

Retail therapy
Currently B&KTS is in the final stages of completing a steel and timber hybrid structure for Asda in Bootle, Liverpool and is carrying out the glulam and structural steelwork for a Sainsbury’s store in Dartmouth.

The new Asda store is a glulam frame and a glulam internal mezzanine with I-Joists, and cold rolled purlins to the roof areas. Dartmouth has used curved glulam for the roof structure with structural steelwork being used in the back of house areas.

“You will always need structural steelwork to make the timber frame stand up,” says Milestone. “Timber cannot achieve the load bearing capacity, that’s why you need the structural steelwork to act independently of the timber frame.”

This month B&KTS will begin work on a £1m bus depot in West Ham for London Transport and a Tesco store in Cheetham Hill in Manchester.

More than 70% of B&K’s clients are repeat customers. And after carrying out new builds for retailers, B&KTS is also assessing work within commercial industrial where steel sheds have had the lion’s share of the market for years.

Factory construction output is expected to weaken over the next two years. Companies are facing higher input costs, due to high-energy prices, with steel being particularly affected by both the rise in energy costs and the price of Iron Ore; whereas the raw material cost for timber appears relatively stable. “The lure of a 25% reduction in cost from using a steel and timber hybrid might convince firms who are teetering on the brink of  consolidation to expand.

Milestone says B&KTS is also in talks with the Olympic Delivery Authority over a couple of potential projects, which might lend itself to some of the smaller venue designs like the Basketball Arena.

The biggest drive for firms to use the hybrid stems from cost and environmental credentials.

The glulam offsets the steel’s high embodied energy, while the ratio of steel offsets the cost of completing the structure in 100% glulam. “To do the whole thing in glulam would be at least a 40% increase in costs compared to a steel frame,” says Milestone. “But by introducing hybrids we can reduce that premium to within 25% and without compromising the carbon footprint.”

Milestone explains the hybrid offers clients a carbon neutral structure without paying a hefty premium for 100% glulam. “Because we are a structural steelwork fabricator we can combine the use of steel and glulam effectively under one package, which has historically been split into two.

“We’re looking at ways of innovation through design to reduce the volume of glulam required to ensure it remains competitive for the future. By using various design techniques, through spans, columns and positions we can make the timber more effective.”

There is also a significant advantage of using glulam in terms of fire risk, as wood has better inherent fire properties than steel. “We can design a column naturally to per form in a one-hour fire resistance, whereas structural steelwork unprotected would only last for maybe 15 minutes before it would collapse. When glulam is in a fire it will naturally char, whereas steel will yield after 15 minutes.”

The species of timber used for the glulam is spruce and larch – predominantly from Bavaria, Switzerland and Scandinavia. Milestone explains B&KTS has identified two types of certification to ensure its glulam is from sustainable and legal sources: FSC and PEFC.

Despite the credit squeeze and many retailers pulling back their spending on new stores, Milestone is confidant B&KTS can achieve between 5% and 10% growth in turnover annually. “I’d say the market in retail is relatively stable and is still perceived as a growth market,” he adds. “We are now looking at structures for clients that would have been in steel but we’re now looking at them as a steel and timber hybrid.”