In Australia, timber is one of the most popular materials to use in construction and design. This is not only because of its functionality and sustainability, but also due to its numerous health and wellbeing benefits.

While it’s indisputable that timber can contribute to a more comfortable and pleasant indoor environment, research has shown considerable physiological and psychological benefits of incorporating timber in a space³.

These include:

• • Reduced stress / calming
  • Lowered blood pressure and heart rate
  • Perception of warmth
  • Improved air quality and respiratory health
  • Increased concentration and improved productivity
  • Expressed visual preference for the space
  • Perceived connection to living things.

As it happens, a study conducted by the University of British Columbia shows that the visual presence of timber can actually lower stress more effectively than plants, while rooms with roughly 45 per cent of timber surfaces boost perceptions of comfort and lower blood pressure⁴.

Our affinity for timber and the innate instinct people have to seek connections with nature and other living systems is a phenomenon known as biophilia.

“The term “biophilia” literally means “love of living things”. But unfortunately, our modern habitat, a built environment, has for the most part separated us from the natural world. In fact, most Australians spend over 90 per cent of their lives indoors, which regrettably corresponds with reports of increasing levels of obesity and mental health issues in society¹.”

Biophilic design is a concept used within the building industry to increase human connectivity to nature through incorporating design elements such as light, airflow, plants, water features and organic materials. This design practice not only aims to make a space more appealing, but studies have found that biophilic design also supports cognitive function, physical health, and psychological wellbeing². These are referred to as ‘biophilic responses’.

Besides from timber’s countless health benefits and timeless aesthetic, it also offers various other practical advantages. Along with providing versatility and endless design possibilities, sustainably sourced timber is also critical for carbon capture and storage, environmental management and conservation, as well as local employment and economic resilience. Ultimately, our innate preference for timber essentially stems from its ability to create healthier, happier and greener spaces.

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References:

1. Wood: Nature Inspired by Design, An update of the Wood – Housing, Health, Humanity Report, Planet Ark, Available at: https://assets.ctfassets.net/fqjwh0badmlx/4kmaYEgVzMOz4ij2IxIcmx/3fbd9975c9f723b3bc518d2968657e42/Make_It_Wood_-_Nature_Inspired_Design_Report.pdf
2. Ryan, Catherine O., William D. Browning, Joseph O. Clancy, Scott L. Andrews, and Namita B. Kallianpurkar. “Biophilic Design Patterns: Emerging Nature-Based Parameters for Health and Well-Being in the Built Environment.” Archnet-IJAR: International Journal of Architectural Research, vol. 8, issue 2 (2014): 62-76. 9 (https://www.archnet.org/publications/9767?utm_medium=website&utm_source=archdaily.com)
3. The nature of Wood: An exploration of the science on biophilic responses to wood, Terrapin Bright Green, Available at: http://www.terrapinbrightgreen.com/wp-content/uploads/2022/01/The-Nature-of-Wood_Terrapin_2022-01.pdf
4. Fell, D. R. (2010). Wood in the human environment: restorative properties of wood in the built indoor environment (T). University of British Columbia. Available at: https://open.library.ubc.ca/collections/ubctheses/24/items/1.0071305

The combination of GLT and CLT is making the construction of entire buildings from timber a reality, and is significantly reducing carbon emissions in the construction industry.

As the world becomes increasingly conscious of climate change and the environment, the construction industry – who are responsible for the largest portion of Australia’s total carbon emissions – are responding through the use of more natural and sustainable building materials.

Glue Laminated Timber (GLT or glulam) and Laminated Veneer Lumber (LVL) have been available in Australia for decades and more recently, the market has seen the rise of Cross Laminated Timber (CLT). These products fall under the umbrella of Engineered Wood Products (EWP). EWP’s offer an environmentally superior alternative to traditional building materials like steel and concrete. One of the most important benefits is timber’s ability to sequester carbon and store it. For example, if we can replace a cubic metre of concrete with a cubic metre of timber, about a tonne (1,000 kilograms) of CO₂ emissions is reduced from the atmosphere.

In order to understand the differences and benefits between GLT and CLT, let’s take a closer look at these products.

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The differences

In GLT, laminates of structural timber are layered and glued in the same direction, on top of each other. This gives the product increased strength primarily in a structural beam or column configuration. GLT can be curved and produced in a variety of shapes, sizes and profiles. Thanks to the natural and warm appearance of timber, GLT is often used as a visually expressed structural support in beam, column, roof truss, portal frame and bridge applications.

CLT is manufactured in a similar way to GLT, except that each layer of timber is glued at 90 degrees to the layer above and below, giving the product strength in both directions. CLT is a ‘whole of structure’ building solution, with similar characteristics to that of a pre-cast concrete panel. Accordingly, CLT panels are often used for box-framed structures where whole wall, floor and roof systems are constructed. CLT can be manufactured to a range of visual appearance grades.

Diagram showing difference between CLT and GLT
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The benefits

GLT and CLT are both natural wood products that share many advantages:

• • Fire and seismic performance – Timber is a combustible material, however, it burns in a slow and highly predictable way. GLT and CLT will not twist or spall in a fire event thanks to their unique charring properties. The self-protecting nature of the charring layer increases the likelihood of a timber structure surviving fire as the uncharred inner core remains unaffected, maintaining its structural strength and stability. When designed for fire performance in accordance with AS1720.4, GLT and CLT are fire engineered to perform as required. In a seismic environment, GLT and CLT have excellent [earthquake resilience](https://www.thinkwood.com/performance/seismic-stability).
  • Natural insulator – Timber is a naturally insulating material that creates a barrier between heat and cold. Its secret is in the many air pockets within the cellular structure of timber, meaning that thermal conductivity increases with species density. CLT buildings offer an additional thermal benefit in that the precise nature of the manufacturing process means that there is very little air leakage within the building envelope.
  • ‍Excellent strength to weight ratio – Engineered timber is lighter in weight than steel or concrete. Its strength-to-weight ratio is approximatively 20% higher than steel and 4 to 5 times higher than non-reinforced concrete.
  • ‍Consistency of performance – Engineered wood products are manufactured to meet specific performance criteria. The manufacturing of GLT and CLT products provides the best solution for an engineered building material.
  • ‍A sustainable material – The process of manufacturing GLT and CLT uses substantially less fossil fuel energy per unit volume than steel, concrete or aluminium, meaning that timber has an ultra-low carbon footprint. In addition, approximately half of the dry weight of timber is carbon, taken from the atmosphere and replaced with life sustaining oxygen, and stored for the life of the tree and subsequent manufacturing process. Chain of Custody certification is important to ensure the products have been sourced from sustainable resources.
  • ‍Prefabrication – GLT beams or columns and CLT floors or walls can be fully manufactured and prefabricated before reaching the job site, enabling quick and easy installation as well as a reported 25 – 30% improvement in on-site project time savings, thus substantial cost savings.
  • Durability – Timber species, glues, treatments and applications are all factors in the durability outcomes of GLT and CLT. Perhaps surprisingly, they can tolerate aggressive environments better than many other construction materials. For example, GLT is ideal for corrosive environments with high humidity or chlorine salt levels such as indoor swimming facilities and coastal locations. The key factor in the longevity of a timber structure is sound design and detailing processes to manage moisture changes.‍
  • Good for the body and brain – Numerous studies have shown that being surrounded by natural materials at home, work or school has positive effects our health and wellbeing. A recent report commissioned by Planet Ark has found that exposure to timber products created similar health benefits to those created by spending time in nature. When used well, timber creates buildings that combine many of the key aspects of nature connected design including natural light, air flow and views of natural elements. It can also be used to reflect the shapes and patterns seen in nature, also known as biomorphism.

Designing with GLT is flexible because it can be produced in a variety of sizes, shapes, profiles and curvatures. On the other hand, while CLT is more static, the thickness of the panels can be increased by simply adding more layers, and the length of the panels can be increased by joining panels together. Both GLT and CLT are engineered solutions, and practical design advice is readily available to provide peace-of-mind throughout the design and construction stages.

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The perfect combination

The manufacturing process is the main differentiator between GLT and CLT; with GLT known as ‘the sustainable alternative to steel’, and CLT the ‘sustainable alternative to concrete’.

In a tall building system, GLT can be used in beams, columns and roof trusses while CLT can be used for floors, walls, roofs and stairs. The 2019 National Construction Code has increased the use of fire-protected timber construction systems in buildings up to an effective height of 25 metres. This includes schools, retail premises, hospitals and aged care facilities in addition to the previously approved multi-residential, hospitality, accommodation and office building types.

The combination of GLT and CLT is making the construction of entire buildings from timber a reality, and is significantly reducing carbon emissions in the construction industry.

Use of Hyne Timber’s GLT and XLAM’s CLT in education and residential projects:

• • Monash University Building – Architect NH Architecture‍
    Residential house in Ceres, VIC – Architect: level-ak

In recent years, the construction industry has witnessed a shift towards more sustainable, efficient building methods, with an increased focus on Design for Manufacture and Assembly (DfMA) and mass timber—particularly cross laminated timber (CLT). Pioneered by companies like XLAM, these approaches are helping redefine construction, offering streamlined processes, reduced environmental impacts, and significant time savings.

What is DfMA?

Design for Manufacture and Assembly, or DfMA, is a design methodology that emphasises efficient manufacturing and assembly processes. By integrating DfMA principles into a project’s design phase, architects and engineers can optimise each component to facilitate faster and easier assembly on-site, minimising material waste, labour requirements, and project complexity.

In practice, DfMA involves designing building elements that are manufactured off-site in a controlled environment, with a focus on quality and precision. Once produced, these components are transported to the site for streamlined assembly, where they seamlessly fit together. DfMA’s precise approach significantly reduces the need for extensive modifications on-site, resulting in faster project timelines and predictable outcomes.

Why DfMA and mass timber are a perfect match

When combined with mass timber, particularly CLT, DfMA’s benefits are amplified. XLAM’s CLT panels are produced to exact specifications, making them ideal for off-site manufacturing. The precision of CLT means that each panel can be engineered to fit into the overall structure, eliminating waste, reducing rework, and accelerating the construction schedule.

With DfMA, mass timber buildings can be erected in days or weeks instead of months, a factor that not only saves time but also lowers on-site labour costs. In urban areas, shorter build times mean reduced site disruptions, less noise, and fewer disruptions for the surrounding community.

Key benefits of DfMA with mass timber

1. 1. Reduced construction time and cost – By manufacturing building components off-site, DfMA shortens construction time dramatically. CLT’s lightweight nature allows for easier transport and handling, reducing both transportation costs and the need for heavy lifting equipment on-site. Additionally, rapid assembly means that labour costs are kept to a minimum, without compromising on build quality.
   2. Enhanced sustainability – CLT and GLT, as renewable resources, have a lower environmental impact compared to traditional materials like steel and concrete. DfMA enhances this by optimising material use, reducing waste through precision cutting and fabrication. Timber also has a natural carbon-storing capacity, and when buildings are made primarily from timber, they can serve as long-term carbon storage, further benefiting the environment.
   3. Improved quality control – Off-site manufacturing allows for strict quality control in a controlled environment, resulting in components that meet stringent standards. This approach reduces the likelihood of structural issues arising on-site, as each component is designed to fit accurately with minimal need for modification. Quality control is particularly valuable for XLAM’s mass timber solutions, as their CLT panels are precisely manufactured to deliver the structural reliability and longevity required for modern buildings.
   4. Increased safety and site efficiency – Since DfMA allows for much of the work to be completed off-site, fewer workers are required on-site for longer durations, reducing the risk of accidents. For high-density urban areas, where limited space and traffic congestion can add challenges, DfMA’s streamlined process offers clear advantages.
   5. Greater architectural flexibility – DfMA encourages innovative approaches to design, allowing architects to take advantage of mass timber’s flexibility and aesthetic appeal. With XLAM’s CLT panels, designers are not limited to rectangular or conventional shapes; instead, they can experiment with unique forms, knowing that each panel can be precisely manufactured to their specifications.

XLAM’s role in advancing mass timber with DfMA

XLAM has been a pioneer in promoting DfMA principles in the Australian and New Zealand construction industries, offering bespoke mass timber solutions that cater to a variety of building types—from residential and commercial spaces to public infrastructure. XLAM’s CLT panels are manufactured to meet the specific needs of each project, supporting the transition to more sustainable, efficient, and quality-assured building practices.

As a company at the forefront of sustainable timber construction, XLAM provides an end-to-end service that supports projects from early design through to installation. With in-depth expertise in DfMA, XLAM works closely with architects, engineers, and builders to design, manufacture, and deliver high-quality CLT components that meet the exacting standards of modern construction.

By embracing DfMA with mass timber, XLAM is helping lead a transformative shift within the construction sector, demonstrating that it’s possible to build efficiently, sustainably, and without compromise on quality. The integration of DfMA principles with mass timber creates not only impressive architectural feats but also a promising solution to the environmental challenges faced by the industry.

As the demand for faster, greener, and more flexible construction solutions grows, DfMA with mass timber—championed by leaders like XLAM—will continue to shape the future of Australasia’s built environment.

As the world increasingly turns to timber for its sustainability, strength, and natural beauty, questions around timber’s fire performance are becoming increasingly important. Timber’s fire resistance is often misunderstood, as many assume it performs poorly in fire due to the nature of wood. However, timber has natural fire-resistance properties that make it highly predictable and reliable in fire scenarios, especially when engineered into mass timber products like cross laminated timber (CLT) and glue laminated timber (GLT).

How timber responds to fire

When exposed to fire, timber undergoes a process known as charring, where the outer layer of wood burns and forms a protective layer of char. This char layer acts as an insulator, slowing the fire’s progress into the inner layers and protecting the core of the timber. As the outer layer of wood chars, it also releases gases that dilute the oxygen in the surrounding air, further slowing the rate of combustion. This process enables the structural integrity of the timber to be preserved for longer, unlike materials such as steel, which can warp and lose strength at high temperatures.

The fire performance of mass timber: CLT and GLT

Mass timber products like CLT and GLT take timber’s natural fire resistance to a new level, offering substantial benefits in fire performance. CLT, with its layered, cross laminated structure, provides exceptional stability and strength. When exposed to fire, the outer layers of CLT char at a predictable rate, forming an insulating barrier that slows heat transfer to the core, preserving the material’s structural integrity over extended periods. This dependable charring process allows CLT to perform consistently in fire situations, supporting the overall safety and resilience of the building.

Similarly, GLT is engineered from multiple layers of timber bonded together to form beams, columns, and other load-bearing components that contribute to a building’s fire resistance. As the outer layer chars, it shields the inner core from the heat, which maintains the strength and stability of GLT elements even in demanding fire conditions. This self-protective charring behaviour provides a safeguard for the structure, making GLT an effective choice for critical load-bearing applications.

Together, CLT and GLT offer architects and engineers flexible, reliable options for achieving fire-safe designs in various building types.

Above: Sample cut from an unlined XLAM intermediate floor/ceiling, still structurally intact after total building burnout.

Proven performance through full-scale testing

Extensive full-scale testing of XLAM’s CLT panels have been conducted under real-life load conditions. These tests have confirmed the predictable charring and structural performance of CLT over time, which has allowed XLAM to develop complex, stepwise equations describing the fire performance of their panels. These equations form the basis of XLAM’s Fire Span Tables, which are valuable tools for architects and engineers working with CLT in fire-sensitive applications. XLAM’s Fire Design Guide, which includes these span tables, offers detailed information on CLT fire design and is available for download.

Mass timber’s role in sustainable, fire-resilient construction

Combining fire performance with environmental responsibility, CLT and GLT offer an exceptional alternative to conventional building materials. By embracing mass timber’s fire resistance and understanding its unique characteristics, designers can confidently specify timber in diverse applications, from residential to commercial and even high-rise construction. As sustainable, fire-resistant construction materials become more crucial in our built environment, CLT and GLT stand out as forward-thinking solutions for the future of safe, eco-friendly building design.

Mass timber, such as cross laminated timber (CLT) and glue laminated timber (GLT), is emerging as a preferred choice in sustainable construction across Australia and New Zealand. At XLAM, our commitment to the environment drives us to not only produce these sophisticated building materials but to ensure they’re sourced and manufactured responsibly.

Certified, traceable, and renewable timber stock

At the core of XLAM’s approach to sustainability is the assurance that all our CLT and GLT feedstock originates from our sister company, Hyne Timber, who are known for their rigorous commitment to sustainable forestry practices. Hyne Timber exclusively sources logs from Australian plantations certified under the Programme for the Endorsement of Forest Certification (PEFC). This certification guarantees that each log is not only responsibly sourced but also supports a full Chain of Custody traceability, meaning the timber can be tracked from plantation to product.

Through PEFC certification, Hyne Timber contributes to a cycle of renewal, where every harvested tree is replaced with another. This cyclical process doesn’t just maintain forest resources—it actively enhances carbon capture. As each new tree grows, it draws carbon from the atmosphere, storing it in its wood fibres long-term. This means that when these trees become CLT and GLT products, the carbon remains sequestered within the materials, offsetting greenhouse gases and reducing the carbon footprint of construction projects.

What is PEFC?

PEFC is a global certification system that ensures timber products are sourced from sustainably managed forests. The PEFC Chain of Custody certification provides a transparent traceability system, confirming that the timber in each product is sustainably sourced from certified forests. For Australia, PEFC’s National Governing Body is Responsible Wood, which administers standards for both sustainable forest management (AS4708) and Chain of Custody certification (AS4707). This local oversight through Responsible Wood adds another layer of assurance, ensuring forests are not only replenished but also managed in a way that protects biodiversity and the quality of surrounding ecosystems.

Carbon sequestration in CLT and GLT

One of the most unique features of mass timber is its capacity for carbon sequestration. Trees naturally capture and store carbon dioxide from the atmosphere as they grow, mitigating climate change. When timber from sustainably managed forests is converted into CLT and GLT, that captured carbon remains “locked” in the timber for as long as the structure stands, effectively acting as a carbon bank. This means that every mass timber building constructed using XLAM’s CLT or GLT not only saves emissions compared to traditional materials, like steel or concrete, but actively stores carbon, contributing to a net-positive environmental impact.

Minimising waste: Efficient production and on-site benefits

Beyond sourcing, the production of CLT and GLT is engineered for sustainability. Both products are manufactured using standardised panel sizes, designed to be customised and cut to specification before leaving the facility. This precision minimises wastage both during production and on-site. At the construction stage, CLT and GLT can be installed with significantly fewer adjustments, reducing waste even further and cutting down on the time, labour, and machinery typically needed. This efficient installation not only reduces the environmental footprint of the building process but also leads to safer, more streamlined project timelines.

Building a greener future with XLAM

As more developers, architects, and engineers look for ways to build sustainably, CLT and GLT are emerging as optimal choices that deliver both performance and environmental responsibility. Mass timber not only offers structural strength and design versatility but aligns with the growing emphasis on sustainable building practices, from carbon sequestration to resource efficiency and waste reduction. Through partnerships with responsibly managed forests and adherence to the highest standards of certification, XLAM is committed to making sustainable construction a reality.

By choosing CLT and GLT from XLAM, builders and developers are supporting a greener future for construction—one that respects natural resources, safeguards biodiversity, and builds responsibly for generations to come.