Timber, when sustainably managed, is the only major building material Australia has that is fully recyclable and renewable. That is according to Professor Keith Crews, Director of the Australian Research Council’s Research Hub to Advance Timber for Australia’s Future Built Environment.
Speaking to ABC Sydney’s Nightlife program, Crews said timber’s credentials over steel and concrete are well established, but yet, with very little growth in forest plantations over more than four decades and with the cessation of native harvesting in WA and Victoria, it must look “outside the box” to ensure it has the timber stock needed to meet demand for housing and other critical infrastructure.
In Queensland, Crews said the Crisafulli government is now working with the value chain to look at ways to expand its timber base, which it considers essential to meeting housing needs over the next 25 years. “It found that it needs to increase its (predominantly) softwood plantation mix by 15 to 20% to meet its housing targets,” he told Nightlife Host Phillip Clark.
“What we need to do is to plant more trees,” Crews said, adding that Australia must replant as much as it harvests to meet demand for sustainably managed timber. And the answer, he suggested, could lie in agroforestry, which promises to be a win‑win for farmers who grow trees alongside grazing livestock, especially in coastal areas that are home to productive pasture and tree growth.
“This is a hot issue, because the best land for trees is also the best land for agriculture,” Crews warned. But agroforestry offers a pathway that does not force the landowner to choose between the two. “It is viable provided there is a guarantee that the farmer can harvest the logs…(instead) they can have healthy livestock and healthy trees that can diversify income.”
“We need a different way of thinking and a different model,” Crews told Clark. “If you look at Austria, where we import a lot of engineered wood from, they think of the next generation and their grandchildren. We don’t have that mindset yet, but we need a longer-term mindset.”
How do we make timber products fully circular?
According to Crews, timber is one of the few building materials that can achieve near net-zero: “If we design buildings for a 100-year design life, and if the plantation pine grows for 30 years, and it lasts for 100 years, it means that wood has been regrown at least three times during the building’s lifecycle.”
It can also be perfectly preserved under controlled landfill conditions, with research by the NSW Government’s Department of Primary Industries (DPI) revealing that 95% or more of the timber buried one metre underground stayed in pristine condition. “I’ve seen this with bridge piers and wharf structures where (thanks to no oxygen) they are in perfect condition,” Crews said.
But instead of going to a landfill, Crews said one of the Advance Timber Hub’s major focuses is to prevent landfill waste and instead work out how timber can be disassembled and reused in new ways. “We call it design for deconstruction,” he said, which is an acknowledgement that timber, as well as steel and concrete, are all precious materials that must be preserved where best they can.
“A lot of products like beams and walls that go into buildings can be repurposed,” he said, whilst researchers are now looking at ways that engineered wood products, and their joints, can be repurposed at the end of life. And then there are housing frames that arrive to site and are assembled with nail guns. If we can redesign these parts, Crews said, we can make it more economically viable for crews to break them down and reuse them at the end of economic life.
- For more information about the Advance Timber Hub and Professor Crews research, click here for Wood Central’s special feature last year.
