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Making the case for wooden buildings

Doggerel Ι April 21, 2017

Walk into the cavernous atrium of the National Building Museum a few blocks north of DC’s National Mall, and you’ll find a piece of wood whose scale rivals the 75-foot-tall, 8-foot-diameter masonry columns it sits next to. This 64-foot-tall plank, which the curators of the current exhibit Timber City have dubbed “The Pylon,” floats next to another 40-foot-long, 10-foot-tall section called “The Beam.”

Together, they’re a potent demonstration of the power of mass timber, a back-to-the-future structural material that uses one of the oldest building materials on the planet in stronger, exceptionally sustainable ways.

Timber City pays homage to cross-laminated timber (CLT), which gains its strength — comparable to steel — from joining perpendicularly stacked sheets of wood with adhesive.

Curated and designed by Yugon Kim and Tomomi Itakura, founding partners of Boston-based architecture firm ikd, and National Building Museum curator and Virginia Tech architecture professor Susan Piedmont-Palladino, the exhibition makes the case that mass timber is a new frontier in low-carbon building. It also beats back the fears that have kept wood structural systems out of large buildings since the 1871 Chicago Fire.

Unlike cement and steel, wood “manufacture” doesn’t require injecting tons of carbon into the atmosphere. Trees grow with a little sunlight, soil, and water, all the while absorbing and sequestering carbon dioxide.

And this renewable resource is firesafe. Once pieces of mass timber reach a certain thickness, their outsides will char if exposed to fire. The char acts as an insulator and protects the timber, maintaining its structural integrity.

Via a USDA design competition, mass timber has picked up high-profile sponsorship from the federal government, which sees it as a political sweet spot combining rural economic development, high-skill manufacturing jobs, and green building.

Timber City evolved out of a 2014 Boston Society of Architects show. This version of the exhibit, on display through September 10, was designed to reach the wider public while still remaining relevant for designers.

Kim and Piedmont-Palladino chatted with Doggerel about the show.

This is an exhibition about a very particular material. What’s the exhibition itself made out of?

Piedmont-Palladino: We actually used CLT panels. It’s an interesting challenge for us, because you don’t usually use real building materials in an exhibition design. It’s usually stagecraft with things that are lighter weight and easier to handle.

We wanted the exhibition to be full of the material itself. The displays show the thickness of CLT — people can go up and put their hands on the 6-to-8-inch-thick panels.

“The Pylon” is really astonishing. We have it placed so that it’s close to one of our huge masonry columns, so you get this fascinating scale. We had to assemble that out of smaller pieces of CLT. If you go around behind it you can see how the wood was put together — there was no way you could bring in a plank that was 40 feet long and just tilt it up in the Great Hall. This is a way of using wood at a completely different scale than we are accustomed to.

Kim: The National Building Museum is really an unusual place. It doesn’t scream “museum” when you walk in. A lot of times people walk in and they don’t even know where the exhibitions are. We wanted to use these panels in the atrium and gallery simultaneously as wayfinding, material samples, display apparatus, and installation. We felt that seeing the physical material while reading about it would create a true immersive experience.

How technical did you intend this exhibition to be?  

Piedmont-Palladino: It’s an exhibition about sustainable building. That’s one of the prime narratives we’re getting across. There is a geeky part of this exhibition that’s like, “Let’s talk about the carbon cycle. Let’s talk about what happens when you harvest a tree and how you lock carbon in, and how much carbon is emitted with concrete and steel construction.”

We also wanted to make sure there were really vivid photographs, renderings, and models that answer the big question most of our visitors are going to have, which is “What are these buildings like to live in?” or “What are these buildings going to look like in my neighborhood?”

This exhibition encourages you to reach out and touch it. How did you think through designing such a textural show?

Piedmont-Palladino: We wanted people to understand the weight of CLT without having to pick it up. Having the material all around you, stacked and leaning, gives the sense of walking around a lumberyard.

We wanted people not to think of each panel as just a surface containing information, but as a thing. That slight lean was quite intentional to give that perception of weight and support.

Kim: We wanted to show the material in flux. When it’s leaning, you get this sense of gravity, and a sense that it’s almost being stacked for installation tomorrow.

Piedmont-Palladino: One thing we didn’t entirely anticipate was how it smells. We watch people go into the exhibition and they breathe in and they’re like, “Oh, it smells really good in here!” You’re not smelling paint drying or the outgassing of adhesives. It smells like wood. It contributes to a sensory experience.

In the world of mass timber, skyscrapers get the most attention. But designers and material scientists often say that wood mega-scrapers are great, but aren’t always practical, and are often just highly visible test cases for what wood can do. Instead, the real revolution would be using wood structures for all manner of more prosaic building types: big box stores, schools, etc. Does the exhibit address this disconnect?

Piedmont-Palladino: We went through a lot of discussion about weighing the specialness of each building, or whether part of the message is that regular old buildings can be built this way — which is an interesting message when you’re trying to do an exhibition on architecture, on significant work.

Much discussion was centered on a few projects that aren’t what you might call high design, but are important because of their ordinariness. One of the interesting projects is a motel that was built by Lendlease on an army base in Alabama. You’d never know by looking at the finished building that it’s CLT, but Lendlease has signed on to using this because it’s incredibly cost effective. It’s a two-story motel that looks like every other two-story motel, but it’s built with CLT.

We featured some buildings that are quite small. We showed Susan Jones’ little CLT house, which is fantastic. We have a set of Girl Scout cabins in Utah, which is one of my favorite projects there.

The question we try to raise is one the early Modernists must have struggled with when they were beginning to work with reinforced concrete — what’s the sweet spot for this material?

Kim: We tried to strike a balance between eye-catching projects that would help change common misconceptions about timber buildings and everyday program types like fire stations, hotels, and housing. It’s only a matter of time before mass timber structures will be used for all these typologies.

When we did this exhibition in Boston, there were no significant mass timber structures in the United States to speak of, and no domestic fabrication facilities. All the timber that’s in this show is from US-based factories. In two years so much has happened.

 

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