MICHAEL: Welcome to the inaugural edition of Built Offsite Forum, sponsored by Sensum. Today’s discussion is dedicated to understanding cross-laminated timber and mass timber. Perhaps we can start with David – what’s your view in terms of what mass timber is and its application to the industry?
DAVID: When we talk mass timber, there are three main variations: CLT (cross-laminated timber), laminated veneer lumber or LVL, and glue-laminated timber. Each of these can be combined to perform different functions and applications in a tall timber building. What they bring to a project is a degree of engineering, and therefore certainty, to the structure.
MICHAEL: In terms of cross-laminated timber, we understand that XLam has recently built a factory in Albury-Wodonga, what do you feel is being the level of acceptance for cross-laminated timber and also the industry’s understanding of its application and opportunities?
DAVID: Cross-laminated timber has gained considerable acceptance since about 2005. Really, the key project that ignited its interest in Australia was the Forte building down at Docklands on Bourke Street here in Melbourne. That was the first very large-scale timber building using CLT. Since that time, XLam has worked extensively in New Zealand to develop housing projects through multi-storey buildings. We’ve done some student accommodation facilities over there. In Australia, we’ve done some small houses and we’re starting to gain some acceptance. We’ve done a vertical extension at Monash University in Caulfield, and we’re starting to see an uptake in its use.
MICHAEL: Could I ask you, Tim, in terms of cross-laminated timber and architectural practice, how have you found clients’ acceptance or level of interest in cross-laminated timber or the application of mass timber?
TIM: We’re working through a period at the moment where everybody wants a cross-laminated timber option on their buildings. A key thing about CLT is the speed opportunities; It’s very fast. The second thing is carbon abatement.
Once you get beyond the project management positions, where people are trying to prove the commercial application of the product, the owners tend to then move towards the carbon abatement question. We’re talking large volumes of carbon sequestration available through the use of the product. It’s a very compelling product from a building owner’s point of view.
MICHAEL: Nick, can I ask you, in terms of the level of interest from the public sector, in particular, are CLT and mass timber being readily embraced or is it about more of an education process?
NICK: At the moment it’s an education process because understanding the true cost and accurately pricing the benefit remains a challenge. Initially, the prices come back, and they look high.
DAVID: I’d like to expand on that. A lot of the equation in building and construction is around cost and comparative cost, and unfortunately, you can’t compare cost from a traditional sense with CLT. There are these other things that need to be added back as a benefit or a quantifiable benefit into the project. They typically revolve around time or speed. So reductions in site supervision, reductions in craneage, reductions in people running around, traffic managing and so on onsite, all these costs add up and can be offset against the cost of designing a traditional building.
But as Tim mentioned, the trick for a producer is to find someone to deliver that benefit to the client. That’s really the key. The quantity surveyors have a role, but they’re not getting the cost versus value scenario. How do you quantify health and safety? How do you quantify having people coming home at night because the safety on the site is much better than traditional sites that might not be so safe?
PAUL: There’s another point. The supply chain on CLT from product to site is very direct. You have this very short supply chain and a small number of people involved in the delivery and installation of the product.
That creates these savings in the preliminaries, but it also means that sites can be programmed each month directly much more efficiently. There are fewer people contributing to the construction of the building, which means you’re less vulnerable to delays from trades that need to run in sequence or in parallel. If you look at the risks involved in bringing a building into fruition, the direct supply line associated with CLT is more reliable.
“The supply chain on CLT from product to site is very direct. You have this very short supply chain and a small number of people involved in the delivery and installation of the product. That creates these savings in the preliminaries, but it also means that sites can be programmed each month directly much more efficiently.” Paul Kremer, Head of Sales & Marketing, XLam.
MICHAEL: Another key issue is how to connect the CLT, Glulam or LVL together. I’d like Milos to talk about the various connections and technologies that will do precisely that.
MILOS: With Rothoblaas being in this industry for 26 years now, we’ve been through couple of projects already in Europe and now in Australia. We know the industry is growing and also the demand for engineered fasteners, for safe fasteners, for products that can save you time, which is very crucial in CLT construction. I would add that if we are involved at the very early stages with the draftsmen, with the architects, we can save time on the construction site because we know exactly what products we are going to use: what length, how many screws are going to be used. So the estimator can know how much the construction’s going to cost. That’s a cost-saving curve from our perspective.
MICHAEL: Tim and David, in terms of the use of connectors, do you consider that when you’re designing a building or thinking about using this product?
DAVID: Certainly, from our perspective at Wesbeam, we do. The connection of the elements is paramount to understanding how to put a building together. With LVL, you’ve got several options. Because LVL is made in a panel, and those panels are then built up into larger sections, we can customise the connection between a column and a beam such that we can take advantage of a male-female type connection between those elements. But once those two elements come together, we still need steel, aluminium or bracketry and screws to hold that. Close working relationships between organisations are starting to bring that efficiency through early engagement with consultants and suppliers.
TIM: People understand post and beam because they’ve been around for a long time. Our clients want to see the story of the connection: post-beam connection, post to floor connection. They want to see those expressed in the architecture. We call it the visual performance or the visual outcome. When you’ve got a concrete panel you’ve got a structure that is hidden inside. But where you’ve got a post and beam coming together on the top of a column, it’s often exposed, and they want to see that because it adds value to their environment.
MICHAEL: On the relative cost of CLT, mass timber as opposed to steel and concrete, can you talk to the cost benefit of one material over the other – is there a certain height [where] one has greater advantages over the other?
DAVID: Well, the current tallest timber building that is completed is 18 storeys in Canada. That being said, I think it’s only a matter of months before that’s eclipsed. We ourselves are working on a 26-storey high building here in Melbourne at the moment. I don’t think it’s about how high we can go; it’s how efficiently we can build it. That’s actually the question we really need to ask because I think we’re in a phase of exploration. There is a traditional format for a building, so, take a 9 x 9 grid which is driven by a car park in the basement. Where timber fits into that grid pattern is going to affect potentially how high the building can go; in terms of how many columns, how many beams do we need relative to what traditional construction might require. So as we get taller and taller, of course, sections are getting bigger and bigger just as they are in concrete. I also think one of the distinct advantages that engineered timber products bring to a tall building is that they are half the weight of concrete.
MICHAEL: Another consideration lies in the area of acoustics and flanking noise.
DAVID: The first thing to do is discuss what type of building you’re trying to build; determine what are the standards you’re trying to meet. Is it residential? Is it commercial? Is it for the education sector? Once you’ve got that baseline, then we can look at the design of the building and its acoustic performance. You can set what degree of acoustic control measures you need to put in place.
Flanking noise in a timber building does bring some challenges because of the way we need to connect our corners of a building relative, say, to a concrete building. That being said, concrete performs very well in the low register acoustics but not so well in the high register, and similarly, timber works quite well in the higher register but not so well in the low register. So when we build a timber building, we can be confident that, say, for example, someone walking across the floor in high heels will perform very well in timber, but someone walking across the floor in a barefoot, creating a low thud, is where concrete works better. So if we can introduce some additional mass to a timber design – that can pick up the lower register of the sounds and absorb that acoustic signature, but still take advantage of the timber solution in a higher register.
MICHAEL: I note also that some years ago the National Construction Code changed the rules on building heights.
DAVID: The National Construction Code or NCC has two pathways in order to get your building approved: the Performance Solution and the Deemed-to-Satisfy Solution. In the Performance Solution, there are no restrictions over the height of the building, as long as you can demonstrate that you can meet your FRL (fire resistance level) regardless of the material. The Deemed-to-Satisfy Solution is your “cookbook” type of approach to construction. And as a cookbook, it works in relation to a particular product. They have determined that part of the controls around that will be the height of the building; 25 metres effective height, roughly eight storeys for mass timber.
Michael Dolphin (Built Offsite), Milos Slavik (Rothoblass Australia), Tim Hill (TANDEM design studio), David Bylund (Wesbeam Tall Timber Building Systems), Paul Kremer (XLam Australia) & Nick Strongman (Sensum).
MICHAEL: Some people do have concerns about fire in a timber building; how do you address such concerns? How do you placate people to further understand that living in a mass timber building isn’t necessarily a fire hazard, Paul?
PAUL: The reality is that mass timber has its own inherent fire properties, and it gets to a point where it chars and it creates a carbonous layer, and then it protects the timber inside. So we address this question in two ways. If it’s a traditional construction method where we replace the wet pour concrete with LVL timber, Glulam or CLT, we will then treat the rest of the building as if we would a concrete building, which is fire grade plasterboard and structural systems that then provide the cavity for that room or that area to insulate it to some degree. In terms of exposing it, we would actually add additional layers of timber and we would have sprinklers installed. So, there are two ways you can really address mass timber in a fire sense, and that is to protect it or provide an additional amount of timber material that can be sacrificed in a fire, which will then provide the fire resistance levels to allow people to egress the building safely.
MICHAEL: Can we talk a little about how mass timber may have an application in multi-residential developments?
PAUL: There are three different types of buildings that really fall in that category for us at XLam, and we’re starting to see this globally as well.
Student accommodation is huge. So we’ve got a university, timber is infiltrating that sector quite heavily. Aged care is also another one; Aveo is an example of that in Sydney. And then you have hotel work.
On the domestic front, I think townhouses will probably have a place and maybe three-storey government institutions or refuge centres.
MICHAEL: If I were a developer and looking to think about a mass timber building, where would be a good place for me to start? What would be the first things you would say to me to prime me to think differently about what a timber building is to me as a developer?
TIM: It’s an easy sell for an architect. Do you want the build to be faster? Do you want it to be greener? Is there a value add with your customers when it comes to sustainability?
These are all inherent qualities in timber and most developers now sell to sophisticated audiences, particularly if we’re selling to the domestic market – and people are very interested in the story behind the building’s construction. People are suspicious of supply lines because there’s less transparency, but if you can show them a timber product, they inherently understand it immediately.
“It’s an easy sell for an architect. Do you want the build to be faster? Do you want it to be greener? Is there a value add with your customers when it comes to sustainability? These are all inherent qualities in timber and most developers now sell to sophisticated audiences, particularly if we’re selling to the domestic market – and people are very interested in the story behind the building’s construction. People are suspicious of supply lines because there’s less transparency, but if you can show them a timber product, they inherently understand it immediately.” Tim Hall, Design Director, Tandem Architects.
MICHAEL: It does raise an interesting point about what I’ll call a seismic change in architecture in mid-rise developments, in terms of places that do offer long-term liveability rather than being focused on short-term investment.
TIM: I think that the emergence of timber construction systems has the potential to actually make the world better. By adopting concrete, I’m pushing carbon dioxide out into the atmosphere as fast as I can. The question around the consumer mentality around buildings needs to change. How it changes, I’m really not sure because we’re beholden to a whole lot of other forces in the construction industry, which we can’t control, but we can advocate for change towards timber construction systems.
MICHAEL: Do you think there’s a change from housing being seen purely as an investor-focused opportunity to an owner-occupier one? And does mass timber coincide with that change?
DAVID: I think that there are many other factors at play; the size of the apartment or townhouse, location, whether it offers you the flexibility to grow a family and then maybe become an empty nester. I think there are lots of other questions around those things. But the questions around longevity of timber around the green credentials that come with it are all compelling arguments.
MICHAEL: So, in a lot of respects, mass timber does offer a better answer for a longer term vision?
DAVID: Yes, I think it does – that’s why we advocate for it.
MICHAEL: It does raise the question of education. What does the panel think in terms of how to educate architects and the building community?
MILOS: From our perspective, we’ve been here in the market in Australia for five years now and we see the change starting from the NCC changes [in terms of building] higher with timber, but still the education is not there. There are certain agencies which Australia is lucky to have, like WoodSolutions and FWPA. They are trying to educate, but TAFE [and trades] have to be educated, people coming out of school, the carpenters, that there is a mass timber to work with.
MICHAEL: What are your thoughts on that, Tim?
TIM: I think education is the answer. I think a broadened awareness of footprint on the planet is also an answer. Those things don’t move without outside pressure and the NCC changes are very positive, but at the same time, there’s no commercial incentive. We don’t have carbon taxes. We don’t have incentives except for small incentives around energy ratings. Alongside education, I’d like to see regulatory regimes changing. I’d like to see a broader awareness amongst the people that regulate industries to help make those changes.
DAVID: My role is as much about educating people on how to deliver projects as it is about actually delivering projects. I spend a lot of my time meeting with architects and engineers and speaking in public forums like this. Most architects are keen to use timber. Many of them are not familiar with each of the three categories of mass timber, so I’ll spend time describing what each they are and where they might fit into the potential matrix of a building. But once I’ve made that discussion, they start to understand how it might fit in in the design sense.
MICHAEL: What are your thoughts, Paul?
PAUL: You’ve got to understand the supply chain. You actually have to understand where the stakeholder sits. There’s a different value for each stakeholder. A developer might be looking at, for example, a new real estate space. If you have a concrete car park somewhere in Melbourne, or Sydney, or Perth, and you can currently get six storeys of concrete on top of that, we can go 10 in timber, so you’re improving the real estate value. So a developer might look at it that way. So you need to educate a developer at the developer’s level.
For an architect, there are the sustainability benefits and a different way of constructing that includes the process and the material, not just the material by itself. Then you move to an engineer. Engineers really want to start to stretch things to their absolute limit. They want to use cool things like Milos’ connections and push the limits of what they can actually construct. Then you look at the builder. The builder’s looking at speed and their efficiencies in economies. Building, in a traditional sense, hasn’t changed for 150 years.
And they’ve had concrete available which is one material source. Now there’s an alternative but it’s not just the material, it’s the process, and the process has some very specific requirements within it.
And then from a manufacturer’s perspective, we’re looking at digital fabrication. We’d like to take something that an architect will produce and translate straight down to manufacturing to gain those efficiencies.
MICHAEL: What are your thoughts, Nick?
NICK: For the education department, we try to get projects completed over the school holiday period. The less time onsite, the better, so volumetric is a good solution. Still, we have completed one project using a timber solution. The question is: who should be doing that educating about the product? Is it coming from the supplier, or the architects, or is it the clients, or is it the end user? I think it should be collective, but I don’t know; can you educate the architect so they specify it? Or is it the builders that need to be educated?
“The question is: who should be doing that educating about the product? Is it coming from the supplier, or the architects, or is it the clients, or is it the end user? I think it should be collective, but I don’t know; can you educate the architect so they specify it? Or is it the builders that need to be educated?” Nick Strongman, CEO, Sensum.
MILOS: I think the investor plays a big role. He should also be the one driving the project that he wants to have it in timber and he already realises the benefits of it. We see that in Europe this is the case – rather than spending the money on, I don’t know, good appliances, he spends more money on the product that he wants to live in. That’s why the houses may be more expensive in Europe to purchase and build, but he knows what he’s paying for.
MICHAEL: Thanks very much for being part of today’s forum. I appreciate your thoughts and professionalism.■
Sponsored by Sensum, the Built Offsite Forum series is designed to foster greater acceptance and understanding of pre-fabrication and offsite construction, with each session taking a specific industry focus. An extended video of Forum 1 is available in the digital version of Built Offsite – Issue 11.