The future of cross laminated timber (CLT) and other engineered timber products has attracted a lot of attention this week in The Fifth Estate. For Aurecon engineer Ralph Belperio, timber has the potential to become a top sustainable building material choice – there’s just a few things holding it back.
Carbon-sequestering timber currently outstrips concrete and steel in sustainability credentials, according to Aurecon major project director Ralph Belperio.
He says the time is now for the timber industry to bring this product to the mainstream market because the steel and concrete industries are innovating fast to create greener products.
Designs for large scale timber buildings are already cropping up fairly frequently in universities, which Belperio says is because the sector tends to embrace emerging technologies early.
There’s also now a number of large scale timber office buildings, including plans for a timber addition to Melbourne Central in the CBD.
But despite its many benefits and a “fair bit of interest” in timber at the moment, Belperio said there are a number of barriers holding it back from widespread adoption.
Aurecon and the University of Technology Sydney recently ran an industry workshop to unpack these pressure points.
One significant barrier is the “slight price premium”.
“My sense is that those cost penalties shall ameliorate over time as people become more familiar with it,” he says.
It also helps that the building method cuts costs at the assembly end because it’s faster and wet trades are largely eliminated so there’s no “pumping concrete up 12 storeys.”
The supply chain in Australia is another problem. Many of the buildings are supplied out of Europe because the choice is limited locally, with XLam in Wadonga and Wesbeam some of few Australian-based options.
There’s also a standardisation piece so that authorities stop seeing all plans for timber buildings as brand new, which will lead to quicker approvals.
Another problem is that products are bespoke to the manufacturer and it is not always easy to go back later and change things during a build.
He says this requires a real change in the way the industry designs and constructs buildings.
The material is already pretty efficient at the assembly end, but Belperio suspects that if further efficiencies were unlocked in a manufacturing stage through automatics and robotics, then the material might be even more compelling.
A lack of education was another thing the engineers and university identified. He says there could be a role for TAFE and the university sectors for educating tradesman and professionals about the material, including dispelling some of the common myths.
Some key pros and cons of timber
Belperio is no “timber evangelist” and says every material has its own specific set of constraints.
It is flammable but the risks can be mitigated with good design, including a charred perimeter to protect the core of the timber.
The toxicity of the glues used in most engineered timber has also been a problem in the past, although he says most modern engineered timber products are now made with formaldehyde free-adhesives.
Responsible forest management is also key to ensuring the material remains as sustainable as possible.
One other threat to timber buildings is termites. Again, this is a design issue. Isolating the timber from the ground with a concrete platform is one way of stopping termites, he says.
Some of the key sustainability benefits of timber are that it is renewable, stores carbon, has lower embodied energy than other materials, and has a variety of biophilia-related wellbeing qualities.
It also saves time and labour, among some other lesser-known benefits such as less noise during construction. Belperio was involved in the 25 King Street in Brisbane, one of Australia’s tallest timber office buildings, where it was reported that the site was “much more respectful”.
“When having a conversation, it’s quiet enough that other people hear. Some of the simple things that we take for granted are impacted by this other form of construction.”
Aurecon’s Ralph Belperio will be speaking on this topic at Frame Australia’s Timber Offsite Construction conference in Melbourne early next week.