It is true to say that new species are never invented and not often discovered, and even then not in commercial volumes. The only changes in that respect are greater access to natural forests and new plantations.
New uses are rare too, for wood has been used in every conceivable way since mankind invented tools and learned to make paper.A long period of time saw the arrival of veneer and plywood, hardboard, blockboard, particle board, medium density fibreboard(MDF), oriented stranded board (OSB), laminated veneer lumber (LVL), glued laminated timber (glulam) and engineered products that enhanced the capabilities of sawn lumber for engineers and architects.
The advent of engineered flooring, for example, revolutionised the market for real wood flooring and expanded consumption by developers, retailers, installers and ‘do it yourselvers’.
Wood flooring manufactures in the US, Europe and China have seen continued growth, more jobs and better floors as technical improvements in finishes, installation techniques and increased choice of species have been available each year.
What is also hugely important is that low cost, fast growing plantation species have provided base panels, while the higher value hardwoods, such as teak, merbau, ash, oak, maple and walnut have benefited from greater yield as face material. That is an environmental plus.
In the US and European markets, about 75 percent of production and consumption is oak, from the US, Europe and Russia as the recent Domotex show in Cologne, Germany, demonstrated.The same trend is likely to be confirmed at the NWFA Expo in Phoenix, Arizona, US, in April.
Consumption in China is less clear but any visit to the Domotex show in Shanghai in March will show oak as the key wood species—accepting that bamboo is a grass, not wood.
This raises the issue of oak material availability, at a time when there have been some recent shortages reported. The fact is that dry oak immediately ready to ship and some logs have been in short supply; but the long-term sustainable availability is not in doubt, especially from the US where red oak is underutilised according to a recent UN/ECE report.
Growing all across the Northern Hemisphere oak is a predominant species and managed sustainably under PEFC and FSC certification.Only in one or two countries is oak’s sustainability in question.
The real excitement in new wood technology is all about cross laminated timber (CLT) of which much has been written in the media in the last couple of years, and rightly so.
In fact, one can go so far as to say that the construction world is on the verge of a revolution—at least equal to the invention of board materials such as MDF many years ago.
High-rise buildings are springing up all over the world—London, Vancouver and Melbourne to name a few successfully completed—and many more are on the drawing board.
Wood’s Fire Properties
The amazing benefits of wood are well known to the timber industry but the architectural and engineering professions have been slow to appreciate its benefits; including that in fire it chars and maintains its structural integrity before failing.
Fire is, of course, a primary concern with wood construction, but CLT is actually safer in a fire than steel, which melts at a certain temperature and collapses without warning (for example, Twin Towers in New York).
A thick plank of woodor CLT, will char on the outside, sealing the wood inside from damage. “Steel, when it burns, is like spaghetti,” BJ Yeh, technical services director for APA (the Engineered Wood Association in the US), is reported to have said.
Now it seems that the architectural profession realises that CLT ticks many of its own boxes and their new interest is driven by several key factors.
First is the ease of design by computer technology, linked to the pre-fabrication manufacture of components in a controlled and dry factory environment, rather than on-site.
Installation time on site is dramatically reduced.Andrew Lawrence of engineering consulting film ARUP explains “Timber has many advantages, but I think the biggest is speed. Timber is lightweight and with computer fabrication it can now be machined to incredibly tight tolerances. This makes it ideal for prefabrication and rapid assembly.
“Assembling a timber building is like assembling a giant piece of flat pack furniture. The development of CLT has been a key part of the timber revolution as it gives us a way to create large timber panels which can be used for the walls and floors of entire buildings, without the need for any wet concrete trades,” he adds.
The 17-storey University of British Columbia’s Vancouver student’s accommodation building ‘Brock Commons’ was erected in aboutnine weeks by only six construction workers, as the CLT was delivered to site.
Moving Towards CLT
Lighter buildings require less material and embodied energy in foundations, which is now a key element of the architectural profession’s realisation of their own impact on climate change, as conventional buildings are a major contributor to greenhouse gas emissions in their construction and operation.So the benefit of carbon sequestration of wood in CLT has finally got through.
Add to that the renewability and sustainability of wood, as well as the avoidance of drilling and mining and the tide is turning.Expect more CLT high and low rise buildings in which the door, windows and service apertures can be designed into the prefab panels and columns, where only the lift shaft will require energy-consuming concrete in the future.
Recent examples of CLT that have made visual impact were the eye-catching ‘Endless Stair’ and the ‘SMILE’ in London both in American Tulipwood launched by the American Hardwood Export Council (AHEC) to show that there is still some way to go.
Currently, almost all CLT is made using softwood, but work by ARUP has shown that the use of hardwood is not only feasible but brings advantages of increased strength and slimmer panels.
The latest project to hit architectural headlines with CLT is Maggie’s Oldham—one of a string of cancer care centres in UK, where construction has begun on the world’s first permanent building created using hardwood CLT, designed by architects de Rijke Marsh Morgan (dRMM).
Together with dRMM and Arup, AHEC pioneered the use of hardwood CLT using American tulipwood in creating the Endless Stair for the London Design Festival in 2013. “We co-developed tulipwood CLT for its inherent lightness, strength and expressive warmth,” said Alex de Rijke of dRMM Architects.
CLT technology is not the end, for now innovation must come in fixings, safe adhesives and improved finishes, especially where exposure to inclement climate may be a factor. But as ‘necessity is the mother of invention’ these related products will surely follow the inevitable growth of CLT.