Mass Timber in the Data Center Boom w/ Erik Barth of Gensler

Mass timber projects don’t succeed because of one company, but entire ecosystems.

Office buildings in major U.S. metros are sitting at roughly 20% vacancy. Data centers? Less than 1%. The U.S. is building data centers at a pace the construction industry has never seen, and for the mass timber world, that's a real opportunity.

Erik Barth is a Senior Associate at Gensler in Boston, where he leads the firm's Mass Timber Collaborative. In this episode he breaks down where mass timber fits in the data center boom, why Type III construction has become the sweet spot (not Type IV), how his team handles the structural loads of high-density equipment with a five-ply CLT panel on a steel primary system, what's shifting in cooling tech and code, and why committing to mass timber up front is the difference between projects that work and ones that don't.

If you're exploring mass timber for your own projects, one of the first questions is often “who actually makes the materials?”

To help with that, we created a Mass Timber Producer Map featuring 39 North American producers and fabricators. You can explore manufacturers near your project, see the products they produce, visit their websites, and connect directly with them.

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Transcript

SPEAKER_01 0:00

It's kind of a an ending demand at this point. You know, the vacancy rate of data setters is less than one percent. You know, whereas you look at office buildings, and depending on what your s what city you're in in the US, it's 20%. So it the demand is pretty remarkable. So the mass timber sustainability and just the story in general about around mass timber is very strong. And when you apply that to a project type like a data center, it becomes a really significant opportunity. Because mass timber can be assembled very efficiently in a prefabricated manner off-site, and it can be then brought on site and can significantly reduce construction schedule. It creates, compared to steel or concrete, a pretty tremendous opportunity to get a whole bunch of square footage built much faster, which is needed for the associated demand with data centers.

SPEAKER_00 1:13

Some are much higher. Data centers, less than 1%. Right now, the US is building data centers at a pace that the construction industry has not seen before. Spending has more than tripled in the last three years, and no other commercial real estate category is even close. So what does that mean for the mass timber world? A real opportunity, if we can get it right. The carbon map is there. Mass Timber runs 35% less embodied carbon than steel, 60% less than concrete. We're talking about buildings going up at a half million square feet plus a pop. And the market is starting to notice. Big players like Microsoft and Meta are both actively building mass timber in their data centers now. And by some estimates, roughly 10% of all mass timber sold in 2025 went into data center-related projects. Today's guest, Eric Barth, is one of the people figuring out what getting it right looks like. Eric is a project architect and senior associate at Gensworth, where he leads the firm's Mass Timber Collaborative. He also teaches graduate level mass timber and sustainable design at Wentworth Institute of Technology. Here's what we cover. First, where and how mass timber actually fits inside the data center boom, how they function, where they need to be built, and the primary reasons clients are turning to mass timber. Second, the code path. Why type 3, not type 4, has been the sweet spot for these projects. And third, future-proof. The tech inside these buildings is evolving very fast. From air cooling to liquid cooling, battery layouts are changing, and more. Eric walks through how to design the structure today so that the building you put up in 2026 isn't sitting half empty in 2040 for the same reasons a lot of office towers are right now. If you're designing, engineering, or developing data centers, or you're trying to get mass timber into one, this one's for you. All right, let's get into it.

SPEAKER_01 2:56

My name is Eric Barth. I am a senior associate at Gensler in Boston. I've been at the firm a little under nine years. Uh I am one of the leaders of our firm-wide mass timber group that uh started probably five or six years ago, almost seven years ago at this point. And I'm one of our regional design resilience sustainability leaders for the firm as well. So I'm an architect on a daily basis, and and most of what I do is is project focused. I also uh lead a whole bunch of research efforts uh across the firm looking into sustainability, material decarbonization, uh design, and uh delivery efforts. So wear a whole bunch of hats uh at Gensler and uh love what I do.

SPEAKER_00 3:47

So it sounds like you don't stay very busy then.

SPEAKER_01 3:49

Definitely not no.

SPEAKER_00 3:53

Uh on the topic of mass timber and data centers, lots of talk about both, whether it's mass timber or not. What do you think? What is driving data center construction like in general? And then like how is mass timber playing into that conversation?

SPEAKER_01 4:07

Yeah, so great question. You know, data center centers are at the center of attention right now, no pun intended for the public discourse uh in many ways, uh, primarily just because of the need for computing um power. And that can take many forms. Um, but that that computing power needs a home and it needs it very quickly and you know, exponentially increasing uh demand for space for processing power, processing units, whether that's GPUs or CPUs, uh in strategic locations. So it's that that demand for being able to process and store um data has grown exponentially and it and it continues to grow. And the associated space needed to house that processing power is is needs to grow with it.

SPEAKER_00 5:01

And then Mass Timber. Why is everybody talking about Mass Timber data centers? Real quick, if you're getting value from this podcast, you should join us at the Mass Timber Group Summit. Every year we bring together the design, build, and ownership teams that are pushing Mass Timber forward for three days in Denver. It's a pretty networking forward event, and our sessions focus on the newest and most innovating topics that'll help you stay ahead in the industry. Everybody leaves with connections that'll move their business and their projects forward. Click the link below or go to MassTimber.group to get registered.

SPEAKER_01 5:28

Yeah, so MassTimber, uh, you know, as everyone, most people listening to this podcast are probably aware is just an amazing material solution in many ways. There's the decarbonization side of it, there's the sustainable forestry side of it, there's the biophilic element of it of being around a material um that's natural, that's beautiful, um, that it's just it's very humane, right? So the mass timber sustainability and just the story in general about around mass timber is very strong. Um, and when when you apply that to a project type like a data center, uh it becomes a really significant opportunity because mass timber can be assembled very efficiently in a prefabricated manner off site, um, and it can be then brought on-site and uh can significantly reduce construction schedule. Uh it creates compared to steel or concrete, uh, a pretty tremendous opportunity to get a whole bunch of square footage built uh much faster, which is needed for the associated demand with data centers. So it's it's the bio, it's the whole sustainability biophilia story along with that speed to market and construction when you combine those. Uh and just to add to that too, thinking about data centers, you know, the the immediate follow-up question I would have to the statement I just made is well, you know, how many people are really in there to experience the wood? And I think what a lot of people don't realize is these data centers need, you know, people to basically take care and monitor um the equipment 24-7. You know, there's no uh you don't turn the data centers off really uh fully. So, you know, there is that that biophilic element does have an impact, you know, sp on the people who are are working, adjoining or in in these uh facilities.

SPEAKER_00 7:31

So yeah, and that makes a ton of sense. And you kind of add you stole my follow-up question about who's actually in there to to work, but that obviously makes a lot of sense. So you're actually working on a mass timber data center right now. I won't ask you who for, but how did how did you arrive with this client? What was that journey like? Why did you approach them about mass timber? Was it vice versa?

SPEAKER_01 7:54

Yeah, I think it came down to the client wanting to do the right thing and us uh at Gensler with a focus on sustainable design and and positive community impact, connecting the dots and encouraging that. Um, you know, it wasn't uh, you know, early early stages it was considered. And, you know, um kudos to our clients and many of our clients who, you know, take take those calculated risks to invest in something that's good for the planet and good for people. Um, so it was a little bit, is a lot of back and forth early on that you know, the flame was kindled just from general knowledge, and then we kind we we uh stoked that flame through you know our technical expertise and backing and and networking and getting the right people involved early on and and um setting the project up for success.

SPEAKER_00 8:44

And I imagine one of the things data centers in general, I'm sure Mass Timber has a complicated point into it, but is code. Like what makes data centers complicated from a code standpoint compared to other building types?

SPEAKER_01 8:55

Yeah, great question. Um and in the code realm for mass timber, the new type four codes are are typically get the most attention, you know, the the um new subtypes of type four dedicated to uh mass timber. Uh and they do present a lot of opportunity with data centers, it's just an enormous amount of square footage. Uh, you know, you're looking at 500,000 to a million plus square feet per building. Um and to be able to get a building type and occupancy that meets that uh, you know, that just massive uh size, but then also the technical requirements of of having it, you know, moving a ton of air or water or um equipment, you know, you have you layer that on top of the the construction type. It's a it's a challenge when it comes to code. You know, typically, historically, data centers a lot of times they're they're type two. Um we for mass timber found that type three was the best fit for um several reasons. I think the the main one being just the um uh the fact that your primary structure does not need to be fire rated, um, which has a whole bunch of efficiency there for your connections, for um for costs, for the members themselves. Um and then we were able to see the square footage um based on um based on a variance for the code. Um but that's you know, really type three was what we saw as the sweet spot for construction type for uh mass timber and data centers.

SPEAKER_00 10:43

So with IBC developing pretty rapidly when it comes to mass timber, like we didn't even have that, those subclasses a decade ago. Are you seeing or planning for any future consideration specifically for data centers?

SPEAKER_01 10:58

Yeah, I mean it's a it's an evolving um discussion, you know, plus the technology is changing where it's traditionally been an air-cooled system. Um, you know, in the future it might be predominantly liquid cooled. Um, so that that changes your approach for um, you know, how you do your your ratings and um the overall systems and code approach. You know, on top of that too, you do have to think about where your battery's your battery storage in the building. Is it localized to one room or is it spread out across the units? So all of that technology is evolving. And I think the key is just staying on your toes and being able to adapt and then also um being involved in the discussions that are going on with the ICC and and um generally with code so that you're not caught unawares when when updates are made. And uh we're actively doing that to make sure that we are. Um, but it's it is a moving target, so it's it's hard to say uh, you know, one static approach is going to work. I think it's really just being adaptable and and looking for avenues for implementation in a changing technology and also a changing code environment.

SPEAKER_00 12:10

Yeah, and you touched on a little bit about some of the design considerations and perhaps constraints that you're designing around. You mentioned one being batteries, the other being what's your cooling system. Can you walk me through what you guys are looking at in a data center and what you're designing around?

SPEAKER_01 12:25

With regard to how we're dealing with it now for most of the buildings, it's uh an air-cooled system. So, what that means for mass timber in particular is you know, type four construction. You can't have you can't have a concealed plenum, but you have to fireproof it. Right. So that's what that was another thing that led us to the type three um solution was the um air-cooled system and mean to make sure we had that plenum space to allow for the air cooling. Um, you know, what one thing that comes up consistently when I, you know, hear folks talking about data centers, and as I've learned about them too, has been, oh, well, the technology is getting so much better, it's getting so much smaller, you know, these buildings will not need to exist in the future, is kind of the the initial thought, right? If you follow that pattern forward. Um, but in reality, uh that's not what we're seeing on the ground. Um, what we're seeing is the um just the the capacity and the power of these buildings um will just continue to increase. Uh it's kind of a uh on ending demand at this point. You know, the vacancy rate of data setters is less than 1%, you know, whereas you look at office buildings, and depending on what you're what city you're in in the US, it's 20%. Um, so it's uh the the demand is is pretty um remarkable. Um but all that to say, you know, for the technology uh piece of it, it's yes, it's it's getting more efficient. There's that 18-month uh you know Moore's Law, which uh, you know, at this point it's it's almost um outdated in the sense of uh with AI, um, just because of the insatiable um uh need to to both store and and process data. So uh, you know, in the future it's you know, it seems like the a lot of the equipment, yes, it'll get potentially um per volume more efficient, but then the support equipment, everything around it, you know, the buildings themselves aren't necessarily going to shrink because of that.

SPEAKER_00 14:44

So it's just like you're you're packing more power into the same space as things get better. You're not necessarily the the person that go deep on the different aspects of it. But one of the things that came to my mind when you're transitioning from air cooled to liquid cooled, I imagine that's pretty heavy. What does that force you to consider?

SPEAKER_01 15:04

Yeah, I so you know what we found is that CLT pretty readily supports GPU CPU structural requirements. Um if you mean the added weight of like a water or a liquid versus an air-cooled um system, you know, my sense of that is that that wouldn't be the defining load driver. It would be it would more be the GPU CPUs themselves. Um, I I don't, you know, that's that's I I don't know the details there. Um, but that's what drove the design for um the timber data centers I've worked on is just the actual weight of the GPU CPUs. And we solved that just by using a five ply CLT. Uh you know, a five ply CLT on a steel primary system was more than adequate to support that um with a topping slab as well. Uh so you know, all that to say is mass timber structurally works when it comes to supporting the load for a data center.

SPEAKER_00 16:13

What about the difference between like single story and multi-story data centers? You know, obviously land is at a premium, especially if you're trying to park it in a city in an urban area or adjacent to it. What are you looking at or seeing in the difference between those two?

SPEAKER_01 16:28

Yeah, great question. And just one point on the actual location of data centers is you have to think about layering, you know, where is the infrastructure for both a ton of power and access to fiber cable, right? And then on top of that, affordable land price. So when you layer all three of those together, it it creates a much more limited geographical area where a data center makes sense to build, right? So that's why you're seeing clusters of them across the world and across the country be built where they are, is because where you have all of those factors overlapping, it creates these you know targeted opportunity zones, basically, right? And a lot of those are not highly urban areas, I will say, because uh, you know, I again one of the factors is the the price of land. Um you know, the uh most data centers are not being built in in urban course, right? Because it just financially doesn't really make sense, even if you might have the other two, um, you know, the the infrastructure there. Um, not to say that that couldn't be the case in the future. It's just at you know, at this point in time, it's you know, economically that's what we're seeing. Um so you know, certainly one, two or three story data centers are all possible, typically is one, sometimes two. Um, you know, two, there's some efficiency there um from stacking the the colos. Um you know, one simpler structurally, right? You don't have to, you know, you're keeping everything on the slab at grade, and you're just creating a roof basically. So it it does simplify things, and if you have, you know, affordable land, it might that make more sense. So I I think either case you could apply mass timber. Uh you know, it it just depends on the site and and the the size of the building that you're you're looking at.

SPEAKER_00 18:32

That makes sense. Uh a pushback from people in general for data centers is just ginormous energy use. Where does that energy come from? Carbon footprint, all that. Like we talked a little bit in the beginning about mass timber being able to be a beneficial material in that equation, but knowing that the the built environment versus the operational environment kind of a a big discrepancy there. Like, what's the conversations you're having with your clients around the environmental impact of using timber compared to like the system in holistically?

SPEAKER_01 19:05

Yeah, it's I mean it's an important question. And you know, I think the the short story is we're just on the journey with our clients to figure out how to become better neighbors, right? Because that's and we see a massive opportunity actually with these kinds of um critical infrastructure buildings to decarbonize uh create sustainability measures, implement sustainability measures. Um, you know, so I think we see the opportunity in the um in the global trend of data center construction. So, you know, thinking about how these buildings can give back to communities both locally and then also globally at an ecosystem scale, you know, and when you think about the global aspect, um, you know, the mass timber being, you know, usually 35 to 40 percent less in body carbon than steel, and then up to 60 to 70 percent less in body carbon than concrete, you know, that has a ripple effect that's pretty significant. Um and then the you know, the you think about the local economic impact in rural communities of using mass timber is positive. Um and then even on site, you know, like I said about the folks who who work in these in these um buildings being around natural materials uh in a 24-7 facility is great. And and you know, also construction that's faster, that's quieter, that's more efficient, is better for um neighboring neighbors in the communities where these buildings are being built. You know, that's something pretty notorious about mass timber construction is it's fast, light, and quiet. So that takes a lot of the um the concerns about what's typically a very messy, loud construction process and it and it mitigates them for communities as well. Um, and then just looking holistically at the building too, you know, are there are there ways these buildings can give back to the community if you know if it's creating local amenities, the massing, the specific location, the landscaping, the the facade and the materials. It's like you can really work with all of these things. Um, you know, maybe the local power generation. Um, there's so many ways to think about, you know, buildings in general, and then you know, data centers falling under the umbrella of new construction, um, ways to do it in a positive way.

SPEAKER_00 21:28

And you've touched on some of the different benefits and ways that Mass Timber can play into those um benefits to the building, if you will, whether it's the embodied carbon, the people working in it, being a good neighbor, et cetera. What are you seeing as like the primary driver of the people that are approaching you as clients, these data center developers? Like, what is pulling them to Mass Timber? What's making it most interesting? Is it that employee good neighbor environmental impact? Are there other things that we haven't gone as deep on yet?

SPEAKER_01 21:54

Yeah, I think it's a it's a combination of things. You know, one that I I mentioned earlier is the Speed to market is real, right? Again, we need a lot of square footage built very quickly. And that is one clear advantage that mass timber structural systems have, where they come together very efficiently, you know, with very um very quickly with you know a much smaller crew size um than other types of structural materials. So um I think you yeah, you aggregate that with the sustainability resilience story and impact, and it becomes a really clear opportunity, right? It's it's it's the speed to market um and the efficiency and and coupled with the sustainability story are really the the two. And you know, I think the two paired together, they they create a a pretty strong incentive.

SPEAKER_00 22:51

Taking the conversation a little bit or maybe a lot down the road time-wise, we had touched earlier on you know, techs evolving. Some people are saying, hey, are we even gonna need data centers in the future? You're looking at like, yeah, they'll just be more efficient, they'll have higher output. But eventually, right, like all buildings, like maybe use case changes, maybe the tech does evolve, et cetera. What are you looking at or your clients looking at in terms of like future proofing their asset, right? So you don't end up with that office to residential conversion catastrophe right now.

SPEAKER_01 23:23

Yeah, great, great question. You know, I think the the reality is data centers are very specific in their um in the in the way they operate. Um, where you know, you instead of having your typical exterior wall, a lot of it's louvers, right, to for intake air, right? You have very significant shafts for air exhaust. Um, you know, the spans are very of the the structural bays are very specific um to the the actual uh racks and the colos. Um so in that sense, you know, there's there's very specific constraints um that you need to design within for a data center. I think that said, um, you know, the fact that mass timber is something that you can, you know, disassemble in a way that, you know, other materials would be much more difficult um does um present an opportunity for material reuse at end of life. Um, you know, I think also just the doing the quality building, something that's going to be durable, uh, and that is a pretty open shell, you know. I I've been in some of these buildings before, the equipment's in there. Um, you know, and you could imagine a hundred different uses for these in the future. Um, you know, it's a it's a large grid, it's a it's a very tall ceiling, you know, and I think programmatically um for infrastructure or other types of uses, there's lots of opportunity and just allowing for that flexibility and not in the in the kind of permanent nature of the design. Um, you know, by having that open grid and not really a lot of other infrastructure in there besides from the equipment, um, that yeah, technically you could think of ways to reuse it. So I think it's reuse is is there both on a material tectonic level and also at a building scale where you know it's it's flexible enough for um, you know, despite the very strong design constraints, um, you know, it's flexible enough that it could be used for other other things in the future.

SPEAKER_00 25:49

So you would say with thinking about those things, you're we're not necessarily headed for the office to residential conversion trap that we're in with those asset classes because of just the nature of how data centers are laid out it already has so much flexibility within certain constraints baked in.

SPEAKER_01 26:06

Yes. And you know, it's I think it's it's hard to predict the future, right? But you know, the best practice of of um creating spaces that um are not overly constrained um can help with with that because it's just very hard to predict what's going to be needed, especially for infrastructure type projects like this. You know, who knows what's going to be needed for infrastructure 10, 20 years from now, right? Uh or maybe it's a different use type. Um, but uh yeah, again, I think it's it's just about keeping it the structure, the um fit out, everything as simple as possible um to allow for that change. And even if it stays a data center, the technology, right, is going to change. So, you know, creating creating a layout that can adapt to that is something that we've approached the design with that kind of thinking and stringency to to um make sure that can happen.

SPEAKER_00 27:03

For a developer or owner who's like considering building a data center out of mass timber, like what's the one thing that you'd want them to know that they probably don't already?

SPEAKER_01 27:10

I think it's important to commit to it up front. Um, you know, it's it's um the sooner you can fully commit to a mass timber building and not look back, the more successful it's going to be, and the more you'll be able to realize the efficiency that's inherent to the material. Um there's certainly a place for parallel costing and um models and and uh analysis. Don't don't get me wrong. Um but you know, finding that that um sweet spot of just the right team and committing to the structural system and you know finding the right manufacturer um will set you up for success. But I think the precedents, the early precedents for mass timber data centers that are being built show that it's possible. Right? It's it's it's now that these have been physically built, um, you know, I'm I'm hoping that, and I think what we're seeing is that um folks will realize the the potential for executing them.

SPEAKER_00 28:20

So I'm gonna ask you to put your your future seeing hat and pull out your crystal ball here, but in let's say five, ten years down the road, do you think mass timber for data centers is gonna stay niche or do you think it could become more standard practice?

SPEAKER_01 28:34

Yeah. So I so taking a step back, I you know, I think critical infrastructure and infrastructure in general, there's a massive opportunity for um decarbonization of materials in general. And definitely I think timber and mass timber play a really important role in that conversation, right? Um, where there's a lot of infrastructure that's that's needed. And and you know, the AI-driven data center um boom right now is at the center of it. Um but I you know I think Mass Timber has a track record now of showing that it's extremely adaptable and um a versatile product that can be used for all different building typologies. Um, so yeah, I definitely do see there being a place for it um for the foreseeable future for this building type, but also just for every, almost every critical infrastructure, infrastructure type project, right? And I and I think that ties into the larger materials decarbonization discussion of we just need to reimagine how we're going to rapidly build or repair, you know, infrastructure at a global scale and uh you know, while decarbonizing it. And, you know, I think data centers are great just because they're such a tangible um and and using mass timber and data centers are great because it's such a tangible way to do that at the heart of that discussion.

SPEAKER_00 30:05

Yeah, that's a that's a great nuance, Manson, and I appreciate that. Uh thank you for spending time educating me a little bit on mass timber and data centers. I hope everybody here found the conversation useful. And I look forward to talking to you again soon.

SPEAKER_01 30:17

Thanks, Brady. It's been a pleasure.