The use of timber and wood in construction throughout Australia has undergone change over recent decades and will continue to do so moving forward, an industry expert says.

Speaking during a recent podcast, Dr Alastair Woodard, a consulting structural engineer and director at building and construction material use consultancy firm Technical Promotion & Consulting Solutions (Aust ) Pty Ltd, described how the ways in which timber is being used in construction throughout Australia has evolved over recent decades.

Going forward, Woodard sees opportunities for the industry as a result of the move toward sustainable construction.

Hosted by WoodSolutions shortly before Christmas, the podcast was part of the Timber Talks series which has been hosted by Adam Jones since 2020.

The podcast was Jones’ last as he devotes all of his time to his CLT Toolbox enterprise, which provides structural design software for mass timber.

Five areas of past change

Reflecting on three decades of involvement with the timber industry from the mid-1990s until today, Woodard says that change has occurred across five areas.

1. Movement from unseasoned ‘green wood’ to seasoned wood.

Up until the late 1990s, Woodard says that most timber homes in Australia were constructed using unseasoned wood or ‘green wood’.

Compared with seasoned wood, which has undergone a drying process, unseasoned wood has a much higher moisture content and expands and contracts in response to relatively small changes in moisture.

This offers advantages in terms of flexibility and the ability when used in framing to enable the building to settle onto its own weight and settle into environmental conditions without loss of integrity.

In certain applications, however, the expansion and contraction associated with unseasoned wood can lead to problems. These include doors not open and shutting properly (as the timber has expanded or contracted) or flooring that has become warped.

As a result, there has been considerable effort to provide a greater offering in terms of timber which had been dried.

2. Engineered timber

By far and away, the most significant change within the timber industry has been the development of engineered timber or cross laminated timber (CLT). This has seen timber systems penetrate into the fast-growing market for mid-rise construction.

The importance of this should not be underestimated. According to Horizon Grand View Research, the market for CLT across Australia and New Zealand (ANZ) stood at $US19.9 billion ($AUD 32.1 billion) in 2022. By 2030, the value of the ANZ CLT market is expected to reach $US 52 billion.

(The 10-storey Forte apartment tower in Melbourne was the city’s first apartment building to be constructed using cross laminated timber. Image source: Jaturong YOK Tangtanawit)

3. More timber education

Third, there has been greater penetration of timber related content within education courses offered by universities and TAFEs over recent decades. There has also been an expansion in the resources which are available for architects, engineers and builders in relation to timber construction.

This, Woodard says, has been significant as the timber industry had not previously had extensive engagement with the education sector.

4. Beyond select grade to natural product

Forth, Woodard says there has been movement beyond ‘select grade’ wood toward the inclusion of timber which embraces natural features.

Select grade wood is wood that is as clear of natural characteristics (pin holes, gum veins, burls etc.) as timber can possibly be whilst still displaying enough subtle features to ensure that the look and feel of the product appears to be natural. It offers a sleek, uniform style but delivers little by way of aesthetic feature.

According to Woodard, the movement beyond select grade wood has led to the development of furniture and flooring that features multiple different grades of timber and creates an interesting aesthetic feel and appearance.

Getting to this stage was not easy. Across the construction industry, there had been a perception that standard grade timber is what architects and consumers wanted. Anything below this was viewed as ‘waste’ and inferior product.

However, Woodard says that the movement beyond select grade wood only reflected common sense – particularly as this grade of wood accounted for only around five percent of timber in Australian forests.

5. Floor Cassettes

A final development has been the growth in floor cassette systems.

Essentially speaking, floor cassette systems are prefabricated units that contain structural components, insulation and other essential elements that are essential for building floors – all in an assembly which can be loaded onto a truck and installed on site as a single unit.

Originally, the idea behind this stemmed from the notion that timber flooring would be ideal as an alternative to concrete slabs on sloping sites and houses that were being constructed in flood zones. This was the case as use of concrete slabs necessitated significant levelling work on sloping sites whilst homes being constructed within flood-prone areas needed to be constructed above the flood levels.

At the time, however, feedback from builders indicated that concrete slabs were easier to manage on a single contract with the concreters. To be considered, timber would need to offer what was offered by concreting contractors: a working surface on a site that was delivered on a specific date at a specific cost under a singular supply and install contract.

In response, the industry developed the concept of floor cassette systems that could fit on the back of the truck and would be simple to install.

Interestingly, however, the industry has shifted its focus away from the ground floor market as floor cassettes have become commonly used in upper floors within mid-rise apartment developments as well as in townhouses.

As for the ground floor market on sloping sites and in flood prone zones, Woodard hopes that the industry will expand its focus to incorporate this market as he feels that floor cassettes offer the best solution for these projects.

Floor cassette systems. Image source: Carters https://www.carters.co.nz/floor-cassette-solutions)

Big Opportunities in Sustainable Construction

Going forward, Woodard sees opportunities for timber arising out of the movement toward sustainable construction.

Timber, he says, offers environmental benefits in several respects.

These include:

• lower emissions in harvesting and manufacturing compared with materials such as concrete, aluminium or steel
• lower emissions during construction as prefabricated timber systems are relatively easy to transport and install on site (as opposed to concrete, for example, which requires longer construction timeframes and more truck movements)
• good thermal and environmental performance during building operation; and
• being readily able to be designed for deconstruction and being able to be reused at the end of building life.

Speaking on the last point, Woodard says that mass timber is screwed together and can be readily unscrewed at end of building life.

Depending upon its condition, the material can potentially be reused in other structural applications (subject to testing) or could be used in appearance products, in flooring (in its solid form), in windows or could be crushed up and made into a strand product.

Even where wood products end up in landfill, research suggests that most of the carbon remains stored within the materials.

(It should be noted that environmental benefits associated with timber construction depend upon products being sourced through sustainable forestry practices.

In Australia, two voluntary certification schemes provide assurance in this area. These are run by Responsible Wood and the Forest Stewardship Council.)

Collaboration Needed

For the industry to achieve best outcomes going forward, Woodard stresses that collaboration is needed.

Here, he sees a worrying trends. When he joined what was then known as the Timber Promotion Council (TPC) in the early 1990s, Woodard says that there were around 80 people across the industry who were producing generic technical work to help the industry move forward. These were spread across timber promotion bodies across various states as well as the CSIRO.

Now, he believes that there are only four or five people who are performing this type of work in a capacity that extends to the entire industry. There are also technical people employed within individual companies, but the work of these people in the capacity of their employment is focused upon individual company objectives rather than broader industry needs.

Whilst he acknowledges challenges which are inherent in collaboration when many parties also compete with each other, Woodard says that it is important that younger and older generations within the industry can exchange technical knowledge that can help the industry as a whole to move forward.

A promising future

In concluding remarks, Woodard said that the long-term outlook remains promising.

“I think that there’s just so much opportunity and scope going forward,” he said.

“It just needs a whole new generation of people coming in to take it forward and (the older generation) holding hands passing on the knowledge and then helping ’em out.”

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