The wood from the trees: what we all need to know about nature’s gift

Mass timber has captured the attention of an industry that’s hungry for lower carbon, sustainable building materials.

No longer reserved as a material for housing, timber will star in Atlassian’s new 40-storey hybrid headquarters in Sydney, a commercial tower intended to raise the bar on sustainable, low carbon design as part of the Australian tech company’s net zero ambitions.

Timber’s attractive embodied carbon properties aren’t its only advantage over other building materials: it’s light, attractive to occupants, and fast and quiet to build with. Increasingly, it’s also cost competitive.

Timber clearly has a role to play in the development of low carbon, sustainable buildings and cities, but achieving these goals is more complex than it appears at first glance.

Questions have been raised about the reliance on timber shipped from the northern hemisphere to supply Australia’s mass timber appetite, and the viability of a sustainable local supply. Waste and re-use also needs to be considered, along with our lack of skilled craftsworkers, and the dark clouds hanging over the Australian forestry sector.

Low carbon credentials

People are very interested in timber’s low carbon credentials, prompting a surge in research, says David Rowlinson, the campaign manager of environmental organisation Planet Ark’s Make It Wood campaign.

Carbon is locked away in wood, with carbon accounting for 50 per cent of a log’s dry weight. It may sound counterintuitive, but an IPCC-supported strategy to prevent deforestation and dial up carbon sequestration aims to harvest trees and use the timber for long-term uses, such as in buildings, and then plant more trees, Rowlinson says.

He says growing trees absorb more carbon, so it makes sense to cut down mature trees and replant them.

“Trees are a bit like us, they become old and less efficient and decay and stop absorbing CO2 as efficiently.”

The material’s carbon-storing attributes are compounded when it’s chosen over conventional counterparts such as steel and concrete – both still big emitters despite manufacturers innovating furiously to lower the carbon intensity of their products.

“The best way to understand this completely and scientifically is through a life cycle assessment,” he says. But that’s expensive and can’t be done with every project.

Shipping versus land transport

Shipping timber from overseas – which has been the only viable choice for many of Australia’s early engineered timber buildings in the absence of local options – does create emissions. The global shipping industry is responsible for about three per cent of global emissions.

But Rowlinson points out that sea freight has a much lower carbon intensity than land freight; and a reliance on imported product is likely to be only an interim solution until the local mass timber industry matures.

He says Australia’s appetite for overseas engineered timber is less about a lack of viable timber for making the product, and more about the absence of local manufacturing facilities.

The introduction of Xlam’s mass timber plant and new products being developed by Timberlink and its new plant in South Australia, for example, will improve Australia’s standing. However, we also need much bigger investment in sustainable forestry and manufacturing capability.

Recyclability in doubt

Despite being described as a “renewable” material, recycling timber is not straight forward. The glues and chemicals used in some products to bind wood together may hamper its recyclability and ability to be safely returned to the earth. 

However, timber does lend itself to disassembly for reuse if it is free of nails and screws, says Dr Joe Gattas from the Future Timber Hub, a university-run research program backed by the state government and industry players such as Arup, Hyne Timber and Lendlease.

Gattas acknowledges achieving true circularity for wood building products is still a work in progress, and something the Hub is looking at.

Queensland government’s Department of Agriculture, Fisheries and Forestry’s Rob McGavin, who is also involved with the Hub, says the glue quantities are so low in volume that “it’s really not an issue” when the material finally reaches end-of-life and is returned to nature.

He even says some glues have been found to make end-of-life easier. Urea-based adhesives, for example, help nutrients leak back into soil.

What about health hazards? McGavin says some glues do have health implications, and so a “pure natural product” is favoured internationally. The serious health risk is when the glues are still wet, during manufacture. Once it’s dry, it’s “no more toxic than a coat of paint”, he says.

Fire risk

The Hub is researching fire risk and trying to understand the charring effect (timber is flammable, but large volumes of timber take a long time to burn, just like large logs on a fire).

Most people now understand the material’s fire risk and are managing it appropriately, Gattas says.

Find out which is more sustainable timber or steel – from The Green List

Other green ticks for timber

Another sustainability benefit is timber’s inherent insulating properties and low thermal conductivity. Engineered timber buildings are built offsite, so an airtight envelope is easy to achieve.

Also, people love wood. Timber expert Michael Lee, CLTP Tasmania operations manager, says that as recently as five years ago, no one talked about biophilia outside of academia; now our innate tendency to seek connections with nature and other forms of life is included in many industry discussions about materials and design.

Higher prices offset by other gains

While sustainability is becoming a major driver for mass timber uptake – with net zero commitments from corporates creating a lot of momentum – the reality is the industry is still motivated by the bottom line.

McGavin says mass timber is a mixed bag on price and, as it’s an industry still in its infancy in Australia, developers can still sometimes pay a premium.

But these extra costs can be offset by gains in floor space or site yield.

He expects prices to decline once builders are able to source timber locally, through Xlam and Timberlink set to improve Australia’s local supplies.

The quiet achiever

Timber is also quiet to build with, and quick and easy to use once the timber arrives on site.

It’s also much lighter than its counterparts, which makes it attractive for retrofit projects such as the recently completed Adina Apartment Hotel at Melbourne’s Southbank perched atop six storeys of commercial office space.

Mix and match

Hybrid construction – teaming timber with steel, concrete and other materials – is also attracting attention. This method opens new avenues for building materials to work in tandem, and play to their strengths.

Rowlinson says that mass timber should only be used where it makes sense – it’s not a matter of replacing all steel and concrete construction with timber.

The race to upskill

A major challenge for tall timber buildings is sourcing skilled labour but that’s improving, McGavin says.

“The good news is no one has ever finished [building with] the product and said it was a horrible experience, which makes it much easier.”

Can’t see the wood for the trees?

Understanding the sustainability credentials of timber starts at ground level.

Australia’s timber supplies come from native hardwood logging, native hardwood plantations and softwood plantations. Softwood plantations supply wood to most engineered timber markets in Australia, such as cross laminated timber (CLT) and glue laminated timber (GLT).

That’s because the use of adhesives between layered formations has dramatically improved the structural integrity of relatively cheap, fast-growing softwoods species such as radiata pine, improving the economics of using timber at scale.

There’s not enough softwood coming out of Australian plantations to meet increased demand for CLT products, says forest certification expert Dr Chris Taylor, a research fellow from ANU’s Fenner School of Environment and Society.

To meet increasing demand for softwood for construction, it’s estimated about half a million hectares need to be planted by 2045. But a lack of investment in plantations so far could see Australia relying on imports.

And that was before the Black Summer – the fires burnt over 5.4 million hectares in NSW alone (the worst state affected) and put significant pressure on available supplies of native and plantation timber.

Taylor says growing demand from the construction industry for softwood products and historically poor resource management that does not account for bushfire impacts in the forestry industry at large is creating a “perfect storm”.

“The problem with industry is it doesn’t account for fires in the system. It’s like a farmer expecting that there will never be a drought.”

A new destiny for native timber

It’s a slightly different story for native timber plantations, which  make up roughly half of Australia’s commercial plantations.

Before engineered timber hit the market, native sawn hardwoods typically went into buildings. Now Taylor says demand for native sawn hardwoods from the construction industry has tapered off.

Most native plantation trees are short rotation eucalypt species (eight to 12 years) grown for woodchips for paper products, with about 10 per cent longer rotation species for structural and appearance grade timber.

Some in the industry, such as CLTP Tasmania’s Mick Lee, would like to see more native plantation trees used in buildings and less in woodchip mills.

In a factory in Wynyard, Tasmania, Lee’s company is making engineered timber products from environmentally managed plantation hardwood timbers, which the company claims is an Australian-first.

CLTP’s plan is not to compete directly with softwood manufacturers, which tend to supply their product at volume, but instead offer a more bespoke product.

Once the market recognises native hardwoods as an attractive option for engineered timber buildings, Lee expects the industry will respond by growing longer rotation species rather than the short rotation varieties that are turned into pulp.

“It’s an exciting time for both softwoods and hardwoods – the real win will be the value add that will be shifting the plantations into the built environment.”

Squaring the circle

ANU’s Taylor says that in Victoria, only a small percentage – about 14 per cent – of a log ends up in buildings for both structural and appearance grade products (flooring, furniture).

Part of the problem is when squaring the circle on a log, there are lots of offcuts. These offcuts don’t go to waste – it’s turned into chips for paper and sawdust for chicken sheds. But that’s still a lot of valuable wood going to low value uses.

Taylor also says that architects could help funnel more timber into higher value uses.

Typically they default to specifying select grade timber in their buildings – the stuff that goes into perfect, knot-free timber floors with all the grains mostly running in parallel. While attractive, a lot of the log needs to be sawn away to get the perfect finish.

“Over the last 30 years, there has been a revival of modernist architecture, which emphasises clean edges and select grade timber as the aesthetically preferred look in many of buildings.”

Logs will go a lot further if architects embrace timber with features, he says.

The Future Timber Hub’s Gattas agrees that boosting the yield of square products from a round log is key to meeting growing demand for the material in the construction industry.

Only 30 per cent of a saw log is turned into a useable timber at a conventional sawmill. The Hub has created products out of timber offcuts that might otherwise be used for “low value” uses, such as woodchips.

He sees this work as core to ensuring there’s enough sustainably-sourced timber to meet the building industry’s growing appetite.

“We’ve got this resource, timber, and got a lot of it, and some is used very effectively in common wood products but with growing demand for tall timber [buildings] I don’t see us at risk of running out of timber, but rather being cleverer with the timber that is available to us, because it will be economically justified.”

He also says it’s important to be able to track products in the supply chain from end-to-end, possible in a small country such as Australia.

“We’ve been able to piece together data from that supply chain so if you wanted to build something tomorrow, I could tell you how much forest it would consume and possibly where it would come from.”

Forestry management in question

The native forestry industry has its own set of issues. There have been criticisms aimed at loggers’ compliance (not meeting sustainability requirements, such as logging in dwindling habitats of endangered animals) and the use of native forest logs for low value uses, such as sending timber overseas to be turned into low value uses, such as tissue paper.

For instance, the Forestry Corporation of NSW (FCNSW) wants to continue harvesting timber in bushfire affected areas despite the devastation wreaked in the summer of 2019-20. In the process it’s attracted the ire of another state government agency, the Environmental Protection Authority (EPA), which is threatening action.

“Where the EPA identifies non-compliance, it will take appropriate regulatory action,” a recent media statement from the agency said. In response, the FCNSW told The Fifth Estate it “takes compliance with the regulations seriously” and would employ additional environmental safeguards in its planned operations.

FCNSW is not alone: native forestry management issues have also plagued Sustainable Timber Tasmania and VicForests.

Chris Gambian, chief executive officer of the Nature Conservation Council, has condemned FCNSW’s inadequate forestry management since the fires. He’s also worried about how much native wood is ending up in low value products.

“The things I see when it comes to native forest industry is the use of the most precious trees is not necessarily matching up with the price we’re paying. We’re pulping fantastic hardwood trees and shipping them to Japan to be turned into toilet paper,” he says.

“If we were talking about putting hardwood timber into power poles, I’d say probably not, but to put hardwoods towards appearance-grade material in buildings, probably we do want to do it, as long as it’s in a sustainable way.”

Getting the regulation right

Australia’s native forestry industry is regulated and abides by an Australian standard for sustainable forest management, which is governed by the Responsible Wood certification scheme.

But Gambian questions why FCNSW doesn’t have Forest Stewardship Council (FSC) certification, the international standard for sustainable forestry operations. Sustainable Timber Tasmania  VicForests also lack the certification.

“We talk about forests in the Amazon and Borneo but in NSW they have a Forestry Corporation that can’t meet FSC. How’s that not a huge problem?” he says.

“How can they, with any credibility, say they have sustainability products and then not follow the standards they ask people in the developing world to follow?”

FSC Australia’s CEO Damian Paull told The Fifth Estate he has observed an increase in consumer and business demand for FSC-certified products in the construction industry, and that burgeoning interest in timber for mid- to high-rise construction has not been missed by the organisation.

He says there is a range of FSC-certified timber construction products available, including in engineered forms.

Knowing the origin of the wood is “vitally important for true sustainability” – which is what certification provides – but there’s no way of knowing how much FSC-certified timber is going into buildings, Paull says.

There’s not that much certified timber compared with non-certified timber, and it’s hard to trace the source of timber used on construction sites if the timber is not certified, he says.

“Anywhere there is timber, there are gaps and imported materials are difficult to trace.”

One upside of engineered timber is that it is made in factories using modern, industrialised processes so it’s more likely to have a transparent chain of custody (a track record from felling to product manufacture).

Furniture is, in fact, one of the biggest gaps in certification as it doesn’t have a chain of custody, says Paull.

One way to ensure more FSC timber ends up in buildings is to certify construction projects, he says.

Growing the whole timber pie

Planet Ark’s David Rowlinson says it’s important to keep growing the whole pie – both plantation and native forestry – to meet built envirnment demand for timber.

He says that is important because Australia is in a $2 billion timber trade deficit, despite being the seventh most densely forested nation in the world.

We have the timber. Now, we need to build capability in engineering and manufacturing so that Australia can extract the most value out of this precious resource, rather than sending it overseas for low value uses, he says.