Where U.S. cities manage to have a high-rise form, the skyscrapers are almost always built with concrete and steel. Could wood soon become part of that mix?
This notion has long been considered untenable because of the perceived fire risk and structural weakness of wood. But a technology called cross-laminated timber (CLT)—where smaller pieces of wood are glued and compressed together—has reduced the safety and fire risks of wood high-rises compared to steel.
CLT has been lauded for its positive environmental impacts—wood construction can capture carbon emissions and emits less than standard buildings. The adoption of CLT could prove a sustainable market-based answer as cities seek to cut pollution from buildings, which now make up almost 40 percent of emissions. Moreover, the material, which is assembled offsite, could significantly cut down on the lag time between groundbreaking and completion.
For these reasons, CLT has already been commonplace in Europe for several decades. High-rise CLT projects have risen sporadically in the U.S., with examples in Minneapolis, Milwaukee, and more, and the International Code Council recently approved mass timber buildings of up to 18 stories.
One such building is even going up in my hometown of Charlottesville, VA, across the street from where I live. The 8-story “Apex project” will be Virginia’s tallest timber building, and will house the headquarters for Apex Clean Energy.
This April, I was given a tour of the building (still under construction) by project leaders, whom I had the opportunity to interview. They included Joseph Marchetti, development president of Hourigan Group, the general contractor; John Pritzlaff, senior VP of Thalhimer and a major project financier; and Alan Taylor, president of Riverbend Development, which developed the project. The interview is edited for concision and clarity.
Why did you choose to build a wood-frame project?
Marchetti: A couple of things. Apex Energy has a mission to maintain a new sustainable environment. The wood frame was a great way to make that happen. It brings a couple of things to the table, in addition to the innate carbon capture benefits of wood. You have a really awesome aesthetic inside. The expectations of what it looks like exceeded what we thought it was going to be….
…The timber itself captures the embodied carbon. The structure is a carbon sink, whereas every other traditionally-built building is a net emitter of carbon. Then you have the ongoing carbon uses vis-à-vis energy. The PV array cuts off about half of that. So it covers Apex Clean Energy’s energy use, the rest of it’s on the grid. We are exploring buying the rest of the energy via renewables, so we can get to that carbon-neutral point.
Describe the actual beams and columns. Is there a special process for making them?
Marchetti: Everything is pre-manufactured and brought on-site. It comes basically assembled, almost like an erector set. The term cross-laminated timber basically means hardwoods that are laminated together, that creates something stronger than they are individually. It’s all put together ahead of time, and it just drives on site, and goes up. The speed at which it goes up is incredible.
What about the fire issue? Does that criticism come up a lot about wood-frame high-rises?
Marchetti: It actually has a better fire rating than steel. The reason is that when it burns, all the oxygen leaves and the fire goes out faster. Also due to the way they laminate it and treat it. If anything it chars—and that’s at a much higher temperature. If the building was made out of steel, it would burn more quickly.
How scalable is the wood-frame model? If you’re the average developer who wants to build a high-rise anywhere in America, what are the cost advantages?
Taylor: The main thing is speed. If you look at a big building, a huge driver is your carry cost…We spent $3.5 million designing this building, and you have to carry that, then the land, then you have to build the building, you have to carry all of that, because nobody starts paying rent until they’re in the space. So you have 4-5 years of carry, and when you have a building like this that can be built more quickly…
Marchetti: The whole building is 187,000 square feet. The timber structure is a little over 130,000. If you were to look at comparable steel buildings, cast-in-place concrete buildings, the wood saves about two months over steel and maybe three or four over concrete. [With CLT] everything has come engineered, and it’s basically put into place.
Pritzlaff: It’s almost like a Lincoln Log, it just slides right in. They pick it up off the truck and it’s there. Labor is another component: for this, you need anywhere between 9-12 workers. A comparable building with concrete requires between three to four times that.
What is the cost comparison for materials relative to steel or concrete?
Marchetti: It’s a little nebulous just because it’s not an apples-to-apples comparison. We probably see somewhere between $5-15 a foot of cost premium to CLT, but a lot of that can be covered by the speed and lower labor costs.
Why is the upfront cost more expensive?
Taylor: It’s just new. It’s like why electric cars are more expensive. It’s not anything intrinsically more expensive. The market has just not yet been created enough to bring it down to normal competition.
What’s the supply network like?
Marchetti: The majority in North America are in Canada. People make it in Europe, so it can be shipped. Obviously, there are cost dynamics related to that. It’s definitely an emerging construction technology.
Taylor: The Canadian company that we’re working with, Nordic Structure, has pine trees and spruce trees mainly. They own their own forest, so when they timber a forest to create this stuff, they replant everything, whereas steel, you take something out of the ground and it’s gone….
Does this project have any government funding?
Timber-frame buildings can rise 18 stories. So why did you build this only 101 feet?
Taylor: That’s the maximum height allowed in Charlottesville.
Would you have added more floors if allowed to do so?
Taylor: Based on the interest in this building, and what we know now, I think we would have definitely added more floors: 2 or 3, no more than 5. But regulations probably would be a handful for us.
All photos credited to Scott Beyer.
This article featured additional reporting from Market Urbanism Report content staffer Ethan Finlan.