Designing with timber: what have we learned?

What sparked your curiosity to work with timber?

DUNCAN: About 20 years ago, I started working with timber. Back then, it was mostly appreciated for its looks and was just one of many structural materials available. My main focus was on honing my skills as a structural engineer and learning how to design with timber. Fast forward to today, and timber has become crucial in shrinking the carbon footprint of our buildings. My interest in timber has grown beyond aesthetics – now, it's all about sustainability for me.

FABIA: When I became a carpenter, I fell in love with the beautiful and versatile material. Growing up in Switzerland, where timber is everywhere, and having grown up in an old wooden house, I always felt close to it. My passion for sustainability naturally grew from that background and got a serious boost during my studies when I delved deeper into the construction industry.

Why build in timber?

DUNCAN: The main reason to use timber today is for its low carbon footprint compared to other traditional materials such as concrete and steel. Despite ongoing efforts to lower the carbon footprint of these materials, timber is crucial for its ability to directly remove carbon from the atmosphere, addressing our immediate environmental needs.

FABIA: Timber is a standout in sustainability, especially when responsibly sourced. Its role in carbon storage and reliance on renewable materials has become crucial amid the growing focus on reducing emissions in construction. Beyond these advantages, its natural warmth is making a comeback in modern architecture, creating inviting spaces. Plus, with benefits like fast construction, low thermal conductivity, and lightweight design, it's a smart choice for cutting-edge projects.

When it comes to responsible timber harvesting, what are some strategies we can use to avoid over-harvesting and minimize harm to local ecosystems?

FABIA: It's crucial for us to be mindful of the source of timber. Where does it come from? How is it harvested? Clear-cutting is the predominant method of harvesting timber, a practice where most of the trees in a given area are uniformly cut down, but there are alternatives. Selective logging is one of them, and precision harvesting is another. As we continue to build in wood and other biogenic materials, there needs to be a greater focus on preserving biodiversity and protecting sensitive ecosystems. We can’t afford to think of timber as a renewable or inexhaustible resource.

Just as importantly, we must optimize the way we construct buildings, prioritizing methods that have the smallest impact on the environment and incorporate what we already have. It is essential to remember the 4 R’s: Rethink, Reduce, Reuse and Recycle. Designing for disassembly and following strategic utilization of wood resources in a hierarchy of applications is critical to limiting the amount of timber harvested and carbon emitted.

When it comes to fire safety in timber construction, what steps can we take to make sure we're doing things as safely as possible?

DUNCAN: It's key to team up with a certified fire engineer who knows their way around timber structures from day one. With all the ins and outs of fire regulations for timber, having a good handle on these details is vital for achieving the safest design possible.

FABIA: Fire safety of timber is relatively simple, as the burning rate of timber can be calculated, and timber doesn’t deform in case of fire as other materials such as steel does. The charring layer of burning wood thermally protects the core of a timber member and thus keeps it structurally sound for much longer than we might expect. The general concepts of fire safety in timber structures are over-dimensioning and encapsulating, but often it’s also possible to avoid risks with sprinklers and other technical equipment. A timber building is equally safe in case of fire than a conventional building, as both fulfill the same requirements.

As World of Volvo is wrapping up, what key lessons or takeaways can we apply to future projects?

DUNCAN: We are always learning when it comes to the capabilities of mass timber structures. World of Volvo represents timber construction on a large scale, and it has been useful to help us better understand the complexities of timber in terms of fabrication, transportation, and installation.

FABIA: Collaboration was the key to success for this project. Our client, advocating for sustainable construction, took risks in embracing innovation with timber. Additionally, we were fortunate to have experienced engineers and contractors as collaborators who played a pivotal role in making the project feasible. Early involvement of these seasoned partners proved crucial, providing valuable insights into solving challenges like the roof beam structure's complexity, long spans, bending radius, and various connections.

In hindsight, considering recent timber projects from the perspective of 2024, is there anything you would have done differently?

DUNCAN: Not all projects start as one that is planned to be built in timber. It might have been interesting to rethink certain building forms with timber in mind, exploring how it could better align with timber's natural constraints, potentially avoiding the need for a material such as steel.

"We can’t afford to think of timber as a renewable or inexhaustible resource. It's all about combining the unique strengths of timber with other biobased materials to create sustainable, adaptable, and forward-thinking designs for the future."

What do you hope the future of timber construction will look like?

DUNCAN: Ideally, all timber buildings in the future will be designed using guidance which draws on the experiences of practicing engineers and architects so that designers unfamiliar with the unique characteristics of timber don’t make the same mistakes as in the past. This will allow a timber architecture to emerge which leverages the best of timber, aesthetically and sustainably, without compromise. Steps are already being taken towards this future with training courses, project presentations, guidebooks and study trips which teach us more about how to design with timber.

FABIA: Looking ahead, the ideal future of mass timber construction goes beyond timber itself. It involves a holistic approach to materials, including rethinking, reducing, reusing, and recycling timber. I hope for a future where we carefully consider which buildings truly need construction and explore how much of the existing building mass can be adapted or transformed. A sustainable future involves a broader utilization of other biobased materials, tapping into the untapped potential of resources like agricultural waste and bamboo.

This diversification minimizes reliance solely on timber, addressing the evolving demands of sustainable construction. There needs to be more regulations to facilitate material reuse. After all, the construction industry stands for around 40% of all global carbon emissions! We can’t afford to think of timber as a renewable or inexhaustible resource. It's all about combining the unique strengths of timber with other biobased materials to create sustainable, adaptable, and forward-thinking designs for the future.