A new kind of wood is taking root among forward thinking designers and builders. It’s a called cross laminated timber, CLT for short. The blog, Tree Hugger calls it a ‘dream material’ and Architect Magazine says it’s a trend to watch.
A project now underway in Radford, will showcase not only the building material, but also and the new vista it opens in the forest. Everyone from bird watchers to train buffs, able bodied and disabled, can get up there near the tree line to see the sights.
Just down from the Glencoe Mansion Museum, where the New River meets the Norfolk Southern train line, is a densely wooded foot path. There’s a bronze statue on the trail of Pioneer, Mary Draper Ingles, returning from her storied kidnapping and heroic trek home from Indian lands. And about a hundred yards from Mary a unique observation deck is nearing completion.
Kay Edge teaches in the school of architecture at Virginia Tech. She and professor of architecture, Edward Becker are co leading the project. Last spring, they and grad students in their design studio began working on this viewing platform project, perched high above the tracks, now nearing completion. One of her students is below us, working in a deep ravine. “He’s adding the last structural column that’s going to hold up the box out there.”
Kurt Helker just graduated with a master’s degree in architecture. “I’m basically leveling out the steel for the columns to rest on top of. You’ve got to make sure (everything is) flush relative to each other. That way the building, once it’s 15 feet high, we don’t have any surprises once we get up there.”
The columns support a structure that looks like an exploded view of a boxcar with what appear to be huge butcher block panels defining the space, holes randomly drilled into the 12-foot-tall and 5-inch thick CLT slabs to create dappled light.
Tom Hammett is professor of sustainable biomaterials in Virginia Tech’s college of natural resources. He says this project is intended to send a message about sustainable building practices.
“It sits in this forested setting so you really get a connection between the wood we’re using in the project and the forest around it. Much of the land in Virginia, that was once deforested, is now forested. Some of the agricultural areas have been reforested and we have a very healthy timber resource ,so we’re looking for markets for that timber resource.”
The wood they’re using to make the CLTs is the ubiquitous yellow poplar, also known as the Tulip Poplar for its showy orange and yellow flowers in spring. They’re considered hardwoods, though they’re not quite hard enough in their raw form so there’s no industry demand for them. But with the CLT process, where they’re cut into sections and bonded into large, thick pieces that look like solid wood, their strength is competitive with steel, and just half the weight. And unlike steel that has to processed in high temperatures, the raw material for cross laminated timber, literally grows on trees. “You’re using less fossil fuel and you’re sending less carbon into the atmosphere than you would for steel. And you’re also ‘locking up’ or sequestering carbon in the product.” And that’s another advantage over steel.
Yellow Poplar can grow to nearly 200 hundred feet. They self-seed and multiply quickly. And If they’re not repurposed, like any tree, they just die and decay, emitting carbon as they do. But, when they’re used for a project like this, they’re varnished and preserved. CLTs also known as ‘mass timber’ can be pre-fabricated off site and assembled with basic power tools onsite. Kay Edge says the relative ease of construction is a big plus. “From my perspective as an architect, it goes together quickly" and it doesn’t require specialized labor, so it cuts down on construction costs.
Edge first learned about Cross Laminated Timber a couple of years ago in a class taught by Hammett. Still little known in this country, buildings made with CLTs have been on the rise overseas for years, literally, some reaching 18 stories and heading higher. Because of their ability to withstand shaking during earthquakes, Italy has built thousands and recently, a few CLT manufacturers have opened in the U.S.
Edge says, the building code is catching up with this material. “I think it was first in the building code in 2015 and the building code that will come out in 2021 will allow for 18 story buildings.”
Hammett says, what’s so exciting about this new viewing platform that takes viewers almost right out above the train tracks for a vantage point seldom seen, is that it will be a demonstration of the creative ways builders can use Cross Laminated Timber in design and structure. “Because of its site, because of its nature, it will exhibit not only the quality and the visual effects of using wood, but also the potential of using (CLT) wood in structures.”
Assistant Professor of Architecture Edward Becker isco-leading the project with Professor. Kay Edge. a
They’re waiting on a highway permit for the second part of the structure to be lifted into place with a crane. giving people a bird’s eye view of the train tracks and giving birds a larger audience – the area is considered a fly way –and the observation platform is wheel chair accessible from Unruh drive in Radford.