Timber: Why Architects Are All in on Wood

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Welcome to Deep Green. I'm your host, Avi Rajagopal, the editor in chief of the architecture and interior design magazine, Metropolis. Throughout this season of Deep Green, we're talking to the experts who understand how to make buildings so that they are better for people and better for the planet. And today We're talking mass timber because if there is a defining trend in architecture, especially American architecture of the last decade, it has to be our rediscovery of wood as a construction material.

Mass timber is called that because these buildings are made out of very large. Structural components, like panels or columns or beams, that are all made of wood. And mass timber buildings are coming up all over North America. In fact, there's a bit of a race going on to see who can build the tallest wooden building.

I'm recording this episode in March 2025, and a 32 story building called the Edison just broke ground in Milwaukee, and will likely be the title holder for the tallest mass timber tower in the Western Hemisphere. Now, there's many reasons why American developers, architects, and builders are all timber struck.

There's the carbon emissions. Wood actually pulls down carbon dioxide from the atmosphere as trees grow. So these mass timber buildings are really a tool in the fight against climate change. Plus, they are quick to construct. And can be cheaper to build A 2015 comparative analysis of one to four story office buildings by woodworks found that wooden buildings are 20 to 30% cheaper to build per square foot.

So should we start building everything out of wood? Well, not so fast. Today, we have two amazing guests to help us understand the basics of mass timber and the current state of mass timber buildings. First, you'll hear from Lindsay a professor at Columbia University and the author of the book, designing the forest and other mass timber futures, and how architecture needs to change to truly embrace wooden construction.

Then you'll hear from Stephen Kavanaugh, a principal at the architecture firm, DLR Group, who has designed 3 million square feet of mass timber buildings as part of the largest collection of such buildings in North America. I can't think of two better experts to take us deep into the thinking behind and the practice of mass timber architecture.

First up, Columbia University professor Lindsay Wickstrom.

what inspired you to do your research, write your book, and why is this a good time to ask some critical questions about mass timber?

2020, 2021. I was teaching, um, at GSAP and Advanced Studio at that time that Asked me to create a syllabus that was about introducing students to nature for the first time.

And this was because the studios leading up to that semester were urban sites. And so for the first time, students were to come face to face with territories of production rather than territories of consumption. And when we just think about that as a general topic. I wonder how those things could be co located, you know, how can production and consumption be co located?

We know this best with the phrase farm to table. It's the most common co located production and consumption experience. And so that's how this got off and rolling. And the site I chose was in New York State in the Hudson Valley watershed. And so just that framework,

Launched this question. What does mass timber look like in New York State, which then going down the path of asking that question, I realized

there's this tight knit group of folks that are working on this topic.

And asking these questions. So then I found myself kind of joining that community and learning about what's at stake here. What are people working on? What are people thinking about? What is, what are the hurdles? Learning a lot, really listening a lot and becoming a student, you know, my own way while also, you know, teaching this studio and trying to help students learn about mass timber as well.

And I met folks like Susan Jones, who has this great community. Multidisciplinary practice that is not only about building, you know, beautiful pieces of architecture, but also about

working with the Department of Buildings in order to level up their code, taking time off from her practice to do that work suddenly expanded the way that we practice architecture.

We're not just, you know, concept to construction. It's it's really about helping.

Cities and therefore our country, but also the world to adopt this next material era. And so in that mindset and just realizing how big of a question this was,

I was looking for these books.

What's a good primer?

Like, what do I assign my students on the reading list? And there were books that covered bits and pieces. I have some, there's some great books. Susan Jones book is great.

but none was as comprehensive about,

greenwashing, like challenging greenwashing and challenging or asking the question, who gets to be part of this future?

So I was hoping that my book. would build on the existing knowledge, which, you know, is just starting. We're at the beginning of this material era. Would build on this existing knowledge and add this question. Since we have this next 100 years to rewrite how materials move from territories of production to territories of consumption and hopefully back, like in a more cyclical way, we also have this opportunity to determine who gets to profit from that, who gets to participate in that,

where are those materials going, which communities are going to be healthier because of that.

And so to me, it just gave a much more urgency behind it

I don't know why people got so jazzed about mass timber, of course,

was,

First and foremost, you know, I think in the U. S. around the question of carbon, um, at least that's why the sustainability community really embraced mass timber in the way that it has,

like why, Do we care about carbon for Mass Timber?

How does Mass Timber help with carbon?

first global scale, global annual carbon emissions,

half of those emissions are contributed by the built environment.

And so the operational energy, the fossil fuels that are burned to heat, light, cool,

our buildings, That

contributes 50 percent of that.

So it's like a 25 percent of the global

annual carbon emissions or greenhouse gas emissions is from just turning on the building

and the benefit of energy efficiency.

For us when it comes to carbon is that energy efficiency also makes you more money so you can save money, the less energy you use so that tracks with capital right so inevitably the market is driving down operational energy, the flip side is embodied energy so the fossil fuels it takes to heat or cook the materials that we use to build the built environment.

Specifically, concrete, steel and aluminum require massive amounts of heat, which is called industrial heat and industrial heat contributes more carbon emissions to the global greenhouse gases than all transportation combined,

So if we were to just use

mass timber instead of 20 percent of the concrete.

It would already, it would kind of like save the planet. I hate to say something so easy like that, but just even a little bite of that market with biogenic material has a massive impact.

And. When we think about carbon from a forest perspective and why mass timber is so impactful is because for the first time in the history of cities, we can now replace concrete and steel.

So dense living, not, I mean, we don't need to build like skyscrapers, but high rises, 6 stories, 8 stories, um, even like 4 stories, we can replace concrete and steel with. Materials that regrow.

So then you get into this deeper question of the quality of the forest. And that has everything to do with carbon as well, because.

if you are relying on monocultural

forests that are clear cut as harvests. Those forests are not going to be resilient. What we know from amazing forest ecologists like Suzanne Simard is that the most resilient forest is a biodiverse, multi age forest. So we have to figure out how to get on the cycle of the forest where we're harvesting multiple species in a way that's not destructive to the root systems that can feed the construction industry without depleting the forest.

to me, that is the beauty of Mass Timber,

it's the one place where addressing carbon emissions allows us to also address some of the other things we've not been very good at in the built environment, which is

we suddenly start to care about Life on this planet, species on this planet,

what will it take for us to have enough healthy forests? To switch a significant portion of U. S. construction to mass timber.

if we were to tomorrow say that all construction in New York City had to be from New York State forests, could we maintain the same rate of construction that we've been doing? And build the same buildings essentially replace it one to one.

There's and then there's whole kinds of,

different varieties of how you might determine. When to cut a tree down in the most healthy way. It's it's an interpretive science, which is so incredible There's not just like architecture, you know, no one's designed the same building.

Nobody designs the same forest You have so many parameters to keep into account

we could provide even more construction materials than what we would be using. Without ever depleting

You're kidding.

the trees grow so prolifically when you keep them in the biodiverse environments that they really enjoy that you can figure it out, the volume is not the question.

It's more of the choreography. Like how do we harvest and how do we. Bring this management scheme across private property boundary lines. How do you get everybody into this agreement to do this? It's more of a social challenge than a volume challenge. Yeah,

it is, um, changing the landscape of mass timber as we speak.

we're not used to thinking about our materials quite in that fine grained way. Um. Noting almost like the living character of materials, like, you know, canopy size, or like, you know, trunk size, like, you know, how, how trees grow and things like that. We don't have to think about that when we think about concrete or glass or steel.

how does that change the way we function? As architects and designers,

if we have to now start thinking about

materials, mass timber in this case, that, you know, has a life, but also is biodiverse in itself has, you know, there's many different species involved and so on. And each of those have probably very different,

What we would call supply chains.

I don't, I, I hate to even apply that word here. Um, but you know, they have very different lives.

before

becoming a building, let's say,

how would that change architecture if we started to have to think about all that?

one example

prior to OSB sheets being used in the built environment before that product was designed or invented.

Aspen trees were a blight on

forest owners. They couldn't get rid of it fast enough. It grew so fast. It had no value. It was It was devaluing the forest because they had to spend so much to get rid of these trees that were so prolific. And then somebody invented OSB and now aspen trees are the most cultivated tree on the planet.

And so this, and then OSB, I mean, to take it further, OSB has a distinct aesthetic, a really specific color. And then now, the more you use it or see it, it has a culture. Of OSB. It has this kind of industrial off the grid. We have associations with that material. That's what designers when I talk about choreographing material, you have an impact as a designer to operate across all of those scales, especially aesthetics are now having the possibility of unlocking the incentives around cultivating certain species.

If I were to create The most desirable spaces that could only be achieved with red maple, you would see, I mean, this is like, and, and then it became just addictive, you know, it's spread across all these designers were doing it and everyone was working with red maple. The forest would change. People would plant red maple, right.

To tap into this, people would harvest it more often. The price would change, you know, it, this is a kind of like fluid relationship. It's, I guess, you know, um, Demand and has something to do with it. It's a, it's a way of saying it, but I like to think about how species based design cuts across all these scales from forest to just what it feels like to be in an, in an interior environment or sitting at a wood desk or being inside of a mass timber office space or living inside of a mass timber, uh, bedroom.

You know, I've spoken with folks who live in mass timber apartments and. The smell is different. The sounds are different. You know, in a concrete building you might hear the mechanical or hear someone's heels on the outside in the hallway. In a mass timber building, you hear the wood, um, I don't want to scare anyone.

You hear the wood moving and it's, it's not like an echoey sound. It's a different kind of sound. Um, it's very subtle and it also depends on how you design your buildings to be acoustically, um, treated. But the, sometimes the sap is, you know, coming through the walls. It's a lifestyle right now. And this is also the beginning.

You know, we're just starting to get really good at using mass timber in the urban environment. And I think. If you consider concrete and steel, they've been modernized for the last 120 years. We've been getting good at designing with concrete and steel for 120 years. We're about 10 years into mass timber.

So just imagine what is coming. It's just an amazing amount of expertise that's on the way. Uh, it's exciting to be in these early days. I feel like we're going to look back and think, wow, that was amazing. We did that.

We've gotten so used to thinking about the built environment almost in contrast to the natural environment. You know, we talk about those two things as two separate categories. And of course, what you're talking about, you know, the sap in your walls, you know, it kind of breaks that down.

It kind of, you know, it's, it reminds us. Not just that we live in nature, but that we are nature ourselves,

um, and Mastenberg has such potential of just shifting our mindset in terms of how we relate to the world. And that definitely, you know, came, comes through in your book too, which is so fantastic.

riverside_lindsey_wikstrom_raw-audio_deep_green_0054: Thank you. I agree. I'm so glad you picked up on that. I think that mindsets, that's another. You know, how are we

creating a, a kind of citizen who goes to work in a concrete tower every day? That's a, it's changing your, the way that you think about the world, the way, the way that you relate to other people.

And I would just love to see, to know what a person is like who grows up, who is born and raised and grows up in spaces that are made of natural materials. What is that person's? Approach to other people around the world to carbon to empathy to what are they focused on doing with their lives? How do they spend their time?

I'm just so curious about this next generation of folks growing up in those environments. I think you're right knowing that sap. No big deal. Sap on the walls. We're taking care of our building much more like we take care of our bodies. I love this comparison too, and I, you know, 'cause clients of mine, they get, and everybody, um, that's used to concrete and steel buildings or just, you know, plaster walls, the things that don't require the same amount of maintenance and care wonder about how do you maintain wood in a way that's not gonna rot or get eaten by termites or have this big catastrophic failure.

And I like to compare it to taking care of your body. You would never. Question, you know, cutting your fingernails, like brushing your hair. If you do these things because it's part of maintaining level of health and your own vision for your aesthetic. And so that's how we might start to think about our spaces that we inhabit, that we are care is part of their lifespan.

And the more we care about them, the more we change how long they will last.

That's a really beautiful thought, Lindsay. Thank you so much for spending this time with us today and for talking us through all your ideas and thoughts about mass timber.

so much. Obvious pleasure to be here.

Deep Green will be back with the architect Stephen Kavanaugh. After a short commercial break

 and deep green is back. We're talking mass timber today. And our next guest DLR and deep green is back. We're talking mass timber today. And our next guest DLR group principal, Steven Kavanagh has been working with the developer Heinz on the T3 series of wooden buildings all over North America. Stephen and I sat down to discuss the thinking behind T3, what lessons he has learned over the five completed projects and the six more he has going underway, and how he thinks mass timber might change how America builds.

Here's Stephen.

Avi: what are the T three buildings and how did DLR group get involved?

Stephen: I, first of all, the T three name means timber, transit and technology. it was a decision by Heinz, the developer of the projects, our client, to give this kind of unique office product, a brand. and they wanted to celebrate the idea that it was made out of wood, and really what they were after.

It was a lot, it was a lot of different things that led to it. but one was this idea that, um, you could build, uh, a workplace that was more. Environmentally and socially sustainable. and certainly there was a lot of other factors that kind of launched the first T three the central business districts had lost some of their luster to the sort of redevelopment districts on the, the outskirts of town that, that had this stock of these beautiful old brick and beam warehouse buildings people were turning those into residences and, you know, loft offices. But the buildings had drawbacks. From a, from a technical standpoint, daylighting and systems you know, the efficiency of the envelope and those sort of things. So Heinz was imagining because they actually did own a lot of these buildings, um, and they were always a hundred percent full.

People loved these buildings, but they noticed that people would terminate their leases and leave because of the discomfort. And they thought, Hey, there's gotta be something where we can recreate this charm, you know, of, of these old loft buildings, uh, in a modern way that delivers all the things that Hez would put in their typical class A office tower.

You know, they're known for these marquee towers, Uh, so this was kind of a new approach. And, uh, if you spoke with people from Hinz, you know that they have, uh. ESG goals. And, uh, that was something that aligned with, with our company.

You know, we had, pretty intensive sustainability goals for ourselves. Um, me as a designer, I was super interested in getting involved in mass timber. I, I was always looking, uh. To see, you know, what is next in sustainability. as a designer, I was drawn to the beauty of wood, right? It's just, um, it seems to have this universal appeal. Uh, you know, everybody likes it. Um, everybody responds to it. I think it's just 'cause of the organic nature of so there was a lot of factors, and this is one that I don't think gets mentioned much You know, these redevelopment districts, they don't typically have allow the density say of the central business district. So there was this alignment with the constraints of building of mass timber, right? 'cause the codes have been evolving to allow more. and still to this day, there's this sort of 85 foot datu, for exposed mass timber.

Now that has evolved, there was an alignment between those limits, right. And the building code limits and, the, the sort of zoning ordinance constraints as well, right?

So, well we can't build that high anyway, so can we explore wood? So then the next step was just to, um. Figure out how do we break through the barriers to adopting this type of construction?

Avi: I think we all have a general sense that wood buildings are good because, you know.

trees sequester carbon as they grow, and then if you make a building out of essentially trees, uh, you don't have the same carbon footprint as making it out of steel and concrete and stuff. And I think that general understanding is fine, but having worked on so many of these projects, right, What is it that helps maximize that potential, right? Of the environmental sustainability of these projects? What have you kind of added to that very basic understanding that maybe we may all share by having worked on so many of these buildings? where are the great advantages?

What should we be doing so that we keep that advantage of the wood and the carbon footprint?

Stephen: so the people that are building our wood office buildings, they're usually pretty sophisticated general contracting companies that, um, have built these massive databases of, you know, cost.

And, um, scheduling information for all the systems that they're acquainted, acquainted with, and all the subcontract contractors that they have relationships with. And so, you know, this is like throwing a wrench into that system, right? It's like, oh. We're not gonna make the super structure outta steel or concrete.

It's wood. And then they start scratching, okay, where are we gonna get it? Who's gonna erect it? All the questions start to start to come. Um, so that really has been the, uh, focus of our work as you can imagine. with that trepidation comes a, a cost premium. how do we get around that? How do we, you know, the whole idea is to build more out of wood and with all these buildings we, we always default to wood. We only go to concrete where we absolutely have to. Um, so how do we get around that, that premium? And that was really the focus of so much of our work. It's like, how do we compensate? Because not all of our clients want to, do the right thing in And, and we study numerous ways, uh, to frame the building. Like hotel or resi, it's gonna be flat slab concrete all day long. And there's gonna be limitations to the spans.

You're not gonna wanna form a bunch of beams 'cause that's impractical. similar with steel, you So with wood it was a little trickier because we had to kind of invent these, um, optimized systems.

And in case of office, you know, you're looking for a clear span space. You want something that's logical and divisible for. So that it's very useful, uh, for a variety of users and with our Hinz T three projects, these are speculative office buildings. Um, so they have to work for a variety of users. So we're looking for something very flexible and then optimal in terms of the span Uh, so that is a big part of the design,

Avi: That is so fascinating. you know, doing the one big vanity, mass timber building as a one-off project is one thing, but what you've done is to, you know, repeat that, you know, city after city, uh, and. You know, this kind of learning, right. You know, how do you get that structure just right?

Um, is, is so critical and it comes from this kind of extended engagement with mass timber construction. It's just absolutely fantastic. the beauty of these buildings is one of the, one of the ways that, um, developers might think about their value.

how important is the aesthetics of these buildings to their success, you know, both economically and so on? but also, you know, how do you, how do you make sure that beauty, Is an integral part of your design approach.

how do you kind of celebrate that beauty of the wood in your buildings?

Stephen: Yeah, that's the key word, is celebrating I've, I've had to learn to adjust my approach, to design, and I call it sort of getting out of the way you know, believing in the integrity of the, of the building and the materials.

And, uh, you know, certainly there's all the detail in terms of the spec and the meetings you have with the contractors to ensure that they're, treating the material with care that they might not otherwise, uh, do with other systems. that that's really what we try to do is kind of get out of the way and celebrate, um, celebrate the wood. wood is, is beautiful and sustainable and it's, it spans, um, very effectively, but it, it's terrible acoustically, you know, because it's such a lightweight material.

so we've kind of developed an approach on these projects to this get out of the way approach. It's like, celebrate everything that you have. We polish the concrete floors. If we, if we have to use concrete for lateral systems at the core, we expose it. the first T three, we had to do that 'cause the lease band was so deep, that we weren't able to brace it, you know, with the wood frame.

So we used the concrete core, and we board formed it and exposed it to you. Sorry for that. That noise. There's a train outside going by. Uh

Avi: I have a kind of tangential question for you.

we saw some of the early American mass timber experiments, you know, obviously happen everywhere, but then very quickly, because of where. The strength of American forestry is,

we started to see a lot of high profile projects in the Pacific Northwest and they, you know, had never lost their tradition of.

Wood buildings and,

you know, I feel like I've kind of gotten stuck with that association a little bit, but the incredible thing you're doing with T3 is you're putting these buildings up in in cities all over the country.

and yet in every city, you strive to make these buildings really appropriate for the location they're in, uh, talk to me about,

Dealing with mass timber in this contextual way,

maybe it has a bit of a burden that other building materials don't, right?

Stephen: you know, since the inception of this idea, this timber transit technology, Um, we were, we were placing these buildings in transit connected neighborhoods, right? And so, there was always an acute awareness of the surroundings, uh, the context. And I think as I mentioned before, a lot of these are in these redevelopment districts on the fringe of cities, so they already have a stock of,

there's already that automatic connection with the turn of the century mercantile brick and beam building with. The new modern wood structured,

So, we have that going for us. Um, but then, you know, we layer on more thinking. Uh, and it's usually,

exactly what you're talking about.

How do you connect it? Uh, how do you make it relevant in that particular place?

the things we've done, like for example, on T3 Austin. Is, um, where we did both,

we're the design architect, architect of record and interior designer for the public spaces in the building. Um, we were able to

dive a little deeper into that idea and our interior design team, uh, connected with local artists and, um, and artisans, um, mill workers and such to later on that local, um, You know, in the lobbies, in the, um, in the lounges, in the social workspace.

So we,

try to infuse some of the local, local charm into

early in the Minneapolis project, we were sort of defaulting to this really kind of clean, modern aesthetic, you know, because we were referencing projects in Europe,

Heinz, our client, very shrewdly said, No, this, this is different. This has to feel,

a little more crafted,

that sort of thing. So we started to weave in, um, that building, for example, as a local muralist who did some work. And then we took some historical images, um, from, Uh, a former manufacturer that was on that site, and we, we printed those onto some of the wood panels and, you know, on the booths.

So, we're just trying to knit in some of the, uh, uh, the local history. So,

Avi: Yeah, I think that is one of the most remarkable things you have accomplished with this series of buildings is, know, because of the scale of the program, the number of buildings you've touched, the geographical range of these buildings, you've kind of developed a very, solid American way of building with mass timber.

Um, you know, and I think that's just really incredible, but in turn, this is my big question for you, Stevens, having said all that you've said and pointed out to us all the different ways in which, uh, master buildings, you know, are a significant departure from how we build today. On the positive side, because of the incredible carbon emission savings they have, uh, speed of construction, so on and so forth.

But then in terms of challenges, you know, getting design teams to like, adjust to this new form of construction, really think through what its implications are. Do you think mass timber will change the way America builds?

Stephen: Yes. I mean, the best we know right now, it's really the only, the only way to move forward. Right? If, if you just, if you look, we don't, if you're gonna build a large scale building right now, you, you have three choices, right? Steel, concrete, or wood, you know. Who knows what the future will bring

To me it's the only, it's the only way forward and You and your listeners probably have, you know, if you're interested in this topic You know that the codes are evolving to go higher and higher and higher You know, 180 feet, 280 feet So that's no longer going to be a limitation,

many

forecasters believe that there's going to be increased densification, um,

that's, that's not an issue. And the fact that it's, um, as you pointed out, it's a

takes very low energy inputs to create these, uh, these members. And, of course, it's a renewable resource.

So, you can't say that about any other thing, uh, that you can build with. So, that's why, you know, I believe it is the future.

Avi: That's definitely a future I want to live in. Stephen, um, if you had to pick a touch point, you know, one thing. That's a book, or maybe it's actually a building, it needn't be an American building, or maybe an expert, somebody who's been thinking about wood,

that has either inspired you or that, you know, you've really come to appreciate and you think will inspire our listeners on Mass Timber.

Can you pick something for us, a recommendation?

Stephen: Yeah, for sure. I mean, if, if you have listeners that are sort of on the technical and design side of things, um, Just, just go to Woodworks and, uh, you know, they, they publish a mass timber design manual. It's got tons of great information and case studies, um, as a leaping off point for you.

but I think in terms of inspiration, you know, to, to really kind of,

really get into it conceptually, I would direct you toward Michael Green's TED Talk.

pretty visionary. Um, and I believe the title of it was, Why We Should Build Wooden Skyscrapers.

I would take a look at that. That was very, um, inspirational to me. I remember sharing that very video with, uh, the Heinz team. When we first started talking about, Can we really do a building out of wood?

Check this guy out, you know. Um, if, if for no other reason, um, as, as a for profit developer, you would have these amazing morsels of, um, you know, justification for, for doing something like this. Um, so that, that's a really great, great thing. It was inspirational for me. I was fortunate enough to collaborate with Michael Green after that.

yeah, that's, that's probably what I'd recommend.

Avi: It's wonderful. Stephen, thank you so much for spending this time with us today. And for talking to us about your incredible work on the T3 series of buildings.

the scale and range of what you've accomplished through these buildings is truly remarkable. And I do hope it's going to be one of the reasons that, um, we change the way we build today.

Stephen: Avi, it's been a pleasure, um, couldn't agree with you more, and that's why our push now is to, um, you know, we've done office buildings like this, we're pushing into multifamily and hotel. So, have a good one.

Deep Green is produced by the Surround Podcast Network. This episode was produced and edited by Rob Schulte, with support from Rachel Senatore and Lauren Volker. We're talking to the biggest experts on sustainable architecture and design all this season, and a new episode will drop every month. So catch the next episode of Deep Green in just a few weeks, wherever you get your podcasts.