“Timber is the new concrete. The vast potential and versatility of engineered timber holds the key to construction for the 21st century, just as the 18th century was about brick, the 19th steel, and the 20th was concrete.” Alex de Rijke of London-based architecture firm de Rijke Marsh Morgan Architects.
The time is now for CLT in Australia: developments, barriers and our first CLT house explored
We have it on good authority that cross-laminated timber (CLT) will be a major player in sustainable mid-rise building construction in the future. However, how far into the future that is, and how widespread its effect on Australia’s built environment will be is still a little up in the air, and according to some is much in the hands of the developer.
CLT is used around the world as an alternative to concrete and steel for all or part of a building’s construction and we’ve seen it used in projects up to 10-storeys in height. It is basically formed as timber panels that are fabricated by bonding solid-sawn timber together in transverse and longitudinal layers with structural adhesives. They are said to provide strength and stiffness properties similar to reinforced concrete and, depending on timber species and method of assembly, have much lower embodied energy consumption than many other building processes, such as the production of steel and concrete.
But while the environmental performance and structural strength of CLT has been well known in Australia for years now, its uptake as a viable alternative to concrete and steel in mid-rise building construction hasn’t been so obvious.
In fact, since Australia’s first CLT building went up in 2012, promising a “new era in the future of sustainable development” in the process, less than a handful of projects using the material have been completed on our shores since.
In January 2016, the Australian Building Codes Board (ABCB) announced changes to the National Construction Code (NCC) that will enable timber buildings up to 25 metres in height to be lodged with planning under deemed-to-satisfy provisions. The proponents of CLT construction rejoiced unanimously because the change ultimately takes away another barrier dissuading developers and consultants from using CLT.
Currently, timber building systems are restricted to three storeys under the NCC’s deemed-to-satisfy provisions, with taller buildings requiring an ‘alternative solution’ to be designed and documented to gain building compliance.
The code change, to be effect from 1 May, will bring Australia up to pace with much of the rest of the world in terms of regulation and, for some, is an obvious move away from outdated laws with origins as far back as the 1666 Great Fire of London.
However, it is only one step in the normalisation of Mass Timber Construction (MTC) in Australia and if timber really does “hold the key to construction for the 21st century”, as architect Alex de Rijke says, then there is still a lot Australia has to do in short space of time to position it as a viable alternative to concrete and steel construction this century.
DEVELOPMENTS FOR CLT
Designed by South Australian architects Proske, Verde Apartments at Kent Town Adelaide is a five-storey mixed use residential project which uses CLT for all the load bearing walls, floors and ceilings on the apartment levels, with conventional concrete and steel construction for the lower two levels.
Since migrating from England, Nick Hewson, Senior Structural Engineer at Aecom has become somewhat of a spokesperson for MTC in Australia, lecturing for universities, advising government and the ACBC, writing academic and news articles and consulting as an engineered timber expert for Aecom.
Upon hearing the news that the NCC was changing to encourage more tall timber buildings, Hewson notes that while he wasn’t surprised (he actually wrote a design guide for these type of buildings which was instrumental in the change happening) he was relieved, mostly because it will save his team a lot of time and effort in getting tall timber buildings over the line at planning stages.
“The previous alternative solutions route meant going through time-consuming and costly processes to demonstrate compliance such as consulting with fire brigades etc.” he explains.
“This code change has taken away that leg work and risk.”
But Hewson is more excited about a few other MTC developments in Australian, most notably some recent changes to the local supply chain of CLT products that could be the tipping point for widespread MTC uptake in Australia.
“The biggest shakeup in Australia has been the number of the suppliers of CLT and the increasingly sophisticated services they offer,” says Hewson.
“There are a lot more European CLT manufacturers with Australian representatives nowadays and they’re beginning to take our market a little more seriously.”
The suppliers Hewson talks about are also beginning to understand that Australian builders, designers and engineers who are considering CLT for their project want more than just sticks of timber—they need an integrated service that makes the transition from concrete/steel to CLT easier.
“A couple of years ago there were a lot of people who could deliver timber into the country but it wasn’t enough,” he explains.
“We needed a much more integrated solution to compete with concrete frame contractors—they needed to supply a full system, which includes things like engineering, design input, costing and installation.”