Our Past, Our Future—Our Present is an online roundtable discussion from our “Stone is Structure” webinar, where stone experts explored and weighed in on stone—as an element used primarily as a means of transferring load (other than self-weight), through the structure. The conversation that followed discussed topics relevant to our AEC industry, and touching on different areas of the design and construction process, such as: structural stone design, its sustainability factor and what we can do to overcome any construction challenges.
Speakers: + Mike Picco, President, PICCO + Steve Webb, Co-founder + Director, Webb Yates + Bryan Thorburn, Director of Business Development–Europe & Middle East, Polycor
Moderated by: + Karl Doucas, Principal VP Operations, PICCO
The following is a transcript of the discussion, which has been edited for brevity and clarity.
Q: Why is NOW the right time for structural stone design disruption or rediscovery?
A: Steve Webb—I think that the wide and broad adoption of steel and concrete as a solution in the 1930s for building, really, was based on the ideas that we were going to have limitless energy. People were seeing endless oil reserves, nuclear power…all kinds of stuff. The notion that there’ll be no limitations on energy. Clearly, there is now a real limitation on energy and a real drive for sustainability, so using the materials that are right under the ground is part of the solution for that. I think it’s wrong that stone is left behind as building material. But I also think this issue of sustainability really puts stone back on the agenda.
Karl Doucas—Steve made some great points related to sustainability and how to really view stone and carbon footprint; the small carbon footprint.
Q: How does sustainability factor when the use of stone at structural dimensions, often means using significantly more stone than traditional rainscreen or thin panel facade applications?
A: Bryan Thorburn—The black bars that Steve showed in the slide where you see the carbon footprint vs. tensile strength of the material shows it very well. The more stone that goes into the building means less concrete and steel that goes into the building. So, you have a far less embodied carbon in the building itself; in the actual material it’s going in. The other factor is the longevity of the building. I mean, buildings are now set to survive 50 years. In many parts of the world there are buildings now that are two, three thousand years old built in stone (maybe that’s the extreme). Of course we’re not building for 3,000 years; but, we certainly see that the durability and the resilience is very important. Especially right now with ideas of fire resistance and flood resistance. All of these factors ticks all the boxes in terms of the longevity and the lack of the very, very low carbon use in it.
On the other side, as you have more stone and less of these super airtight insulated greenhouses we've built that need to cool; and needed a lot of energy for air conditioning. All of those arguments the concrete industry talks about, in terms of thermal mass of the operational energy of a building, is super important when it comes to the stone itself. We think about those beautiful mediterranean homes that stay cool even on a hot day. And it’s because of the thermal mass—it breaks that curve of having to add more energy for the cooling and air conditioning, and that’s maybe a challenge we have of this becoming more accepted in terms of being the norm. But what we do know, is a thermal wall of a thick stone wall, for example, is going to help in terms of cooling. And I guess the reason that we’re here talking about this is because it’s not getting cooler. It’s because of rising temperatures. So, I would say that you’ve got the embodied carbon and the operational carbon between both of them.
Karl Doucas—They’ve all shown that the talent exists to bring this type of technology, or this rediscovery of solid stone construction, to the market.
Q: In your view, what are the biggest challenges to using stone as structure in construction? And how do we overcome them?
A: Mike Picco—I think the biggest challenge is really acceptance by the design and construction community. As Steve mentioned, it was the norm back in the day. Then through the 1920s and 1930s it was left aside and kind of ignored as a building material. So, I think we need to know that it starts first with the architects and designers reflecting back on the successful use of stone as structure in the many examples we have throughout the world. From a technology and industry perspective, as Brian mentioned, maybe quarries and fabricators now have to rethink some of their processing; some of their retooling potentially with some fabrication shops moving toward more cubic material. Material handling might be a little different for some of them. Some may be very easy to adapt; but, I think that’s another area where there’s going to be a little bit of a challenge. I truly believe if we do enough research on the benefits of natural stone, we’ll start seeing more and more acceptance, because there are huge benefits there.
Karl Doucas—We have a question from a viewer I’ll pose to all of you.
Q: What are your suggestions to bridge the knowledge gap for architects, engineers and especially building departments related to stone as structure?
A: Mike Picco—I’ll just mention something quickly on the building front. We do always have challenges with building departments even putting two solid columns at the front portico of a house. Demanding that we need a steel column in there; and that we can’t use stone. I usually try and defend it by showing pictures of cathedrals in Europe and saying, ”One of these have steel columns and we’re supporting a 10ft x 10ft portico.” There’s a challenge there for sure! Because it’s been ignored for so long, there’s definitely a gap and a lot of people are uncomfortable with it.
A: Bryan Thorburn—From our side, it’s going to be soldiers on the ground. One by one finding those people who are open to it, trying it and pushing it. And be there to answer questions, with the testing that they’re going to need and be responsive in that way. On the quarry side as well, I think we need to implement some kind of new industry-wide handbook, like the Dimensional Stone Guide. I don’t know how much structural information is in that; but, the big thing is to start tapping into the actual artisans who are working with stone all the time. [Stone] is still there—it’s just become very, very niche. And that knowledge is still there. Ancient medieval guilds in Europe and France have masonry practices that are still being handed down form apprentices and masons.
A: Steve Webb—I really echo what Brian was saying about needing a code of practice—a design code, like the Concrete Model Code. Something that has international acceptance. And we need grading of known quarries. Engineers are terrified of designing with stone. They don’t know how strong it is, and don’t know how to design with it because they haven’t got a code. Very simple. Actually, the amount of work that went into making the Concrete Model Code would be immense. I mean, a lot of laboratory testing, a lot of different people in different countries agreeing to work on. We’re starting to do a little of R&D in the UK at University College London (slightly sponsored by Brian’s company!) and stone masonry companies. Other people are doing research; but, it needs a proper effort, a codification. The minute a Euro code or ASTM reading code is in your hand, the building control guy/building department has nothing to argue about—because he’s got in in a book.
Q: How is cost affected in the delivery of stone, and marshalling it around job sites?
Karl Doucas—I guess the question is stone vs. another material—the space requirements and logically managing solid materials around the tight spaces we all work in from site to site.
A: Bryan Thorburn—It certainly depends on where you are and what kind of space challenges; but, I think space challenges are difficult to begin with. With modern logistics, we find we’re usually delivering per schedule. We have project managers who arrange the priority of that. We’re doing projects in New York City that don’t have room for anything really. So, it’s just-in-time deliveries—it’s deliveries from a yard to the job site. The logistics are there already; but, in the case of maybe a 30-storey building? Yeah, we’re gonna have to come up with a good plan to make sure the flow of stone is coming, that there’s somewhere to store it because it is quite a big volume. But again, we’re not changing the volume of the building itself. Material that has to go into that building in some way.
A: Steve Webb—This idea, the hegemony of concrete—I mean, the stupidity of concrete. If you were an alien that landed on this planet, you’d see all these people sitting three feet above an infinity of stone. And they’ve got mixer trucks, you know, full of mashed up stone to make concrete. The logistics of getting stone out of the ground, turning it into concrete and getting onto a building site…just bonkers! Compared to getting a block of stone, putting it on a truck and taking to site. The concrete can go off in the wagon. You know, you get the concrete trucks backed up down the street. Then they have to go and empty it into a skip because it’s about to go off, or it goes off even before they get it on the building. And you’ve got to pump it up the building, you know what I mean? This is a complete circus…just to use concrete! What are the logistics of stone? You have a truck with blocks of stone that don’t go off, and are immediately set. Don’t need 28 days of curing. Yeah, the logistics of concrete are just totally illogical.
A: Bryan Thorburn—There’s something inherently simple and pure about it, that anytime I’ve had this same discussion with other people, it seems to me to be extremely clear.
A: Steve Webb—If I said to you—you’ve got two ways of delivering a material. One is you put it on the back of a truck and you take it there. And the other one is, the truck has to have a tank on the back of it that has to keep revolving while the truck drives around—you’d be like, “We’ll go for option one.” How are we even talking about option two?!
Karl Doucas—This concludes our roundtable discussion and webinar. Special thanks to our two guest speakers and colleagues in the industry—Brian and Steve, for joining us today and sharing your expertise. I think it’s really added a lot to the conversation and also spread the word of the benefits of stone. I think we’re all on the same page, of the proponents of natural stone being used more in the industry.
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