Back to basics – building with wood (AskNRCan)

Joël Houle: Welcome, everyone, to Ask NRCan. This is a podcast series where we have conversations with our experts to talk about an aspect of the work that we do here at Natural Resources Canada. Today, we’re talking about building major structures like highrises or commercial buildings out of wood.

For those of you who are new to the show, we call this series Ask NRCan because we want to hear from you. The purpose of the show is to share with you not only the type of science that we do but also why we do it. So, at the end of the episode, if you have any questions on this topic, head to Twitter and tweet at us using the hashtag “#AskNRCan”. Our experts will do their best to answer all relevant questions.

Sounds good? Let’s do it.

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Our guests today are GCWood Program Officer Richard Coxford and Senior Research Advisor Mohammad Mohammad. How are you guys doing today?

Richard Coxford: I’m doing great, thank you.

Mohammad Mohammad: Thanks, we’re doing great.

Joël Houle: So you guys are here today to talk about building with wood, but we’re not talking about typical two-storey residential homes here, right? What type of wood building specifically is NRCan supporting?

Richard Coxford: Yeah, so, particularly under the new program that was created by the federal government — the Green Construction through Wood Program — we’re targeting those non-traditional wood buildings. So, we’re looking at high-rise buildings, we’re looking at low-rise, non-residential. So, like box-store, commercial-style buildings and as well as bridges. With over 90 percent of residential homes being constructed in wood, that market is well represented by wood. But when it comes to these non-traditional buildings, the playing field sort of to speak needs to be levelled a little bit and a little more increased use of wood in those sort of categories.

Joël Houle: That’s really interesting. Those types of buildings, like tall wood and low-rise — not commercial, non-residential — construction projects, do those buildings exist already?

Richard Coxford: They do, yeah. There are examples across the categories of wood being used in those types of constructions — it’s just not very prevalent. So for the high-rise buildings, there are a couple dozen high- rise buildings across the world that have been constructed out of mass timber, two of them in Canada: the 18-storey Brock Commons in Vancouver and the 13-storey Origine building in Quebec City. But as far as making it more mainstream, and a normal, easy option for people to build with, that capacity isn’t there yet.

Joël Houle: What type of wood is used in this construction method? Is it engineered wood? Is it regular wood?

Mohammad Mohammad: Actually it’s both. There are some new generation of engineered wood products that have been developed over, I would say, the last 50 or 60 years that are allowing us to push the envelope and build taller with wood and even getting better performance out of those wood buildings.

Joël Houle: You bring up something interesting here with performance: What are the advantages of building structures like these with wood?

Mohammad Mohammad: Wood has major advantages over other construction materials. The first of those actually is that wood is renewable, and the environmental benefits of building with wood do exceed those of other energy-intensive types of construction material. For example, wood can sequester carbon throughout the service life of the building and even beyond if the building or the building elements are recycled or reused, which is really an interesting design concept these days. And, you know, wood in buildings can be designed to be also cost-effective. The speed of assembly, the speed at which the building can be put together using prefabrication, a high level of prefabrication including CNC technology, is actually allowing us to finish the building a lot faster than other materials. And there are a lot of implications associated with that: financial implications, health and safety and noise. Those elements are making it very attractive — for builders, for developers and for designers — to actually build those types of structures out of wood.

Joël Houle: You touched on something that was a concern to me at first: Are these wooden structures safe? My obvious first concern would be fire safety.

Mohammad Mohammad: That’s a very good question. There have been extensive fire testing, structural testing and other types of testing or performance testing such as acoustic performance as well that’s being conducted not only in Canada but across the world. NRCan has been providing a lot of funding to do testing in support of the use or expanding the use of wood in high-rise applications. Because we’re really going beyond the building code targets in a way, we need to demonstrate that those buildings are safe and they can meet the intent of the building code. To do so, the only way to do it is actually by testing, by engineering analysis, by modelling. But regarding fire, mass timber in particular — which is commonly used in high-rise applications — has an inherent fire resistance as it burns very slowly and at a very predictable charring rate. So, any fire protection engineer can calculate exactly how much time it requires to actually achieve a certain fire resistance rating, and he can design those wooden elements in a typical high-rise wood building accordingly, so that they can meet the intent of the building code.

Now structurally, especially in relation to the performance of those buildings under seismic and earthquake conditions, because wooden buildings are actually lightweight compared to other types of buildings such as concrete or steel, that is actually a major advantage when it comes to the seismic design and the resistance against earthquakes. So yes, wooden buildings, wooden high-rises, can be built safely and they can meet the intent of our building codes.

Joël Houle: That’s very impressive and good to know. Why is NRCan taking such an interest in building these bigger structures with wood?

Richard Coxford: NRCan is taking interest on a couple of fronts. One, obviously, from a climate change perspective, wood has the ability to sequester carbon. But also the manufacturing process of a lot of these new engineered wood products is less intensive than some other traditional building materials, so there’s also an avoided benefit as well. The Green Construction through Wood Program, one of the underpinning tenants of that is to support GHG mitigation through that. So, that coupled with the ability, as Mohammed mentioned, to have some of these health benefits and other aspects that wood can bring that some other products can’t, as well as the ability to hybridize some buildings as well, so see multiple different construction materials used in conjunction with each other to create an optimal building envelope, is one of the reasons that we’re pursuing this.

The Government has had an interest for a number of years now actually, starting off with a tall wood building demonstration initiative that took place back in 2013, which saw support go to the creation of the aforementioned two tall wood buildings in Canada: the 18-storey Brock Commons and the 13-storey Origine building in Quebec City. So, with those in place, the demonstration of the benefits of those — which have accrued broadly already across Canada and even globally with both of those projects being recognized heavily — that kind of spurred this new wave of interest and expanding it to the low-rise sort of commercial applications that we had discussed, as well as the bridges. The Green Construction through Wood Program intends to build on that and not just from a demonstration perspective but also through supporting the research and technical aspects required to change the building codes in Canada. We saw in 2015, when the building codes allowed for the maximum stories to be built with wood go from four to six, a boom in that sort of five- and six-level building structures happened shortly thereafter. So, by supporting all this research and targeting the capacity to build higher with wood, then we’re hopefully going to see that same sort of takeoff in industry. And by demonstrating taller buildings as well, you get a sort of trickle down effect, so the research and design and information that gets generated out of these major projects then trickles down to even some of the lower levels. So even, you know, a seven- to ten-storey building and stuff like that can benefit from the work that’s being done.

Joël Houle: Speaking of support, how does NRCan and the Government of Canada as a whole, for that matter, support these new projects and initiatives?

Richard Coxford: Yeah, so we’ve got sort of through the new program that was launched last fall, the Green Construction through Wood Program. It works in sort of three streams. The one that we’ve talked a bit about the most is the demonstration projects. So this is where we provide funding directly for the incremental cost between building with traditional materials and building with wood. Because, under the current sort of building code, these builders that are looking to use wood have to go through an alternative solutions means, which can be a bit costly because that’s not as prescriptive as how you’d normally construct a building. So, we support that incremental cost to do the testing and proof and a lot of the elements that Mohammad mentioned, so ensuring that there is fire safety and seismic safety and stuff like that for the designs that they’re looking to incorporate in these tall wood buildings. So, we provide direct funding to builders looking to construct these high-rise, low-rise and bridge infrastructure pieces out of wood.

We also have two other aspects. The one we’ve touched on a little bit already is the support for codes. So we provide funding to groups like the National Research Council for doing fire testing, code committee work to help revise and adapt the forthcoming National Building Code of Canada, iterations towards supporting more tall wood implications and making those sort of those more prescriptive, so more readily available for designers and builders. And then a third tenant of that program as well is education. So wood in sort of the engineering fields and design and architecture fields is heavily underrepresented, particularly in post-secondary education at this point. So we’ll be working with Canadian associations and other groups to put together more robust capacity in the education system as well for wood.

Joël Houle: Mohammad, I just heard Richard mention earlier bridges. Now, is that one of the next steps in wood construction? Is that what we can expect in our future?

Mohammad Mohammad: Absolutely. Now that the Expression of Interest call for proposals is out for low-rise, non-residential type of constructions, as Richard mentioned — the box-type retail, institutional, commercial buildings — now we’re getting ready to launch the third call for proposals for timber bridges. Building timber bridges or building bridges out of wood is not something really new. There are hundreds of old covered timber bridges that exist in Canada, and even over the last 20 years, there’ve been quite a few built by various provinces — modern-type of timber bridges. So the intent of this program is really to encourage the re-specification of mass timber in particular for timber bridge applications.

We see a huge market opportunity, actually, for using wood in bridge applications. I guess a lot of that is related to the — a lot of that interest is because of the environmental benefits of building with wood. So that’s not only specific to regular buildings, but that’s also applicable to timber bridges.  

Joël Houle: Are we going to see some bridges that are made with engineered wood on a larger scale than we’re used to?

Mohammad Mohammad: Absolutely, there are some modern timber bridges being built in Europe in particular that are multi-span. Those are bridges over highways, some of them actually are highway bridges over rivers, train tracks, et cetera. So yes, with those new generation of engineered wood products combined with the new generation advanced type of connection systems and new treatments, there are new technologies advancements that’s been happening in the wood preservative type of treatments that are more environmentally friendly. So if you take account of all those elements together, I think we have the ability now to design and build large bridges out of wood using those new technologies that’s been developed recently.

Joël Houle: Wow, that’s really, really interesting work you guys are working on. Thank you so much, gentlemen, for taking the time to talk to us today.

Mohammad Mohammad: Thank you.

Richard Coxford: Thank you very much.

Joël Houle: So, this is the end of the episode. But, like always, it doesn’t mean that it’s the end of the conversation. If you have any follow-up questions for Richard and Mohamamd, get on Twitter and tweet at us using the hashtag “#AskNRCan”.

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I think that’s it for us today. Thank you so much for listening! We look forward to hearing from you, and we’ll see you next time.