Researchers at Michigan Tech Want to Create a High-Tech Wood Product Called Cross-Laminated Timber From the State’s Hardwood Trees

The mass timber industry’s promise of low carbon emissions through state-of-the-art laminated wood products has resulted in steady adoption across a construction industry long bogged down by high emissions and habitat destruction. 

But its growth prospects in Michigan’s Upper Peninsula, where hardwood trees predominate, have been less certain because cross-laminated timber (CLT), a type of mass timber used in place of concrete and steel, has traditionally been sourced almost entirely from softwood lumber. Over the next few years, that could change through research being done at Michigan Technological University into new resins that will allow hardwoods to be used in making cross-laminated timber. 

“I couldn’t put a number on when it is going to be on the market,” Mark Rudnicki, the director of the Hardwood Mass Timber Institute at Michigan Tech, said of hardwood cross-laminated timber. “But I don’t think it is good to characterize it as competing with softwood. I see this just as a diversification of wood as a building material. The point is that we want to use all of the biobased material that we can to replace carbon-intensive materials like concrete and steel.”

CLT is a form of mass timber, an artificially produced construction component made from layers of wood and resin that sticks them together. Making CLT is a relatively straight-forward process. Timber sheets are set out in one direction on a press, resin is added, then another sheet of wood is turned 90 degrees on top of it and set down. Repeat this process multiple times until you have a lasagna of wood held together with resin; the pressing machine squeezes it all together, producing a brick or panel. 

This process is ideal for creating large scale, prefabricated buildings at a fraction of the carbon emissions compared with traditional techniques. A 2022 review in the journal Sustainability cited studies which showed that replacing concrete or steel with CLT in mid-rise buildings can reduce manufacturing, transportation, and installation emissions by 13 to 26.5 percent, depending on how the project is designed. 

“The issue on hardwood versus softwood CLT is getting the manufacturing process right so that we develop a panel that can be certified as being a structurally sound panel,” said George H. Berghorn, a professor of construction management and sustainable wood construction at Michigan State University. 

Michigan Tech researchers now need to work out what types of resins work on what species of tree, at what pressures, and over what periods of time, Berghorn added. “That’s what gets tested and codified into the manufacturing standard, which then gives us the ability to have a certified, stamped, structurally sound product,” he said. 

Michigan’s economy is much more diverse than just the auto industry. The northern two-thirds of the state are decidedly rural and, especially in the woods surrounding Michigan Tech in the Upper Peninsula, largely reliant on the lumber and mining industries, as is much of the northern United States and northern Ontario. Mining and logging employs about 8,000 people in Michigan, according to the Bureau of Labor Statistics.

The challenge is that unlike in the Pacific Northwest or Australia, where softwoods such as pine, spruce and fir predominate, the trees in the Upper Peninsula  are almost entirely hardwoods. By introducing a hardwood CLT resin, Michigan Tech researchers are hoping to expand the pool of resources available for architects, developers, builders, urban planners, home buyers and businesses looking to build or renovate existing buildings in a more environmentally friendly way. 

Rudincki and his colleague Xinfeng Xie are researching resins for sugar maple, red maple, yellow poplar, yellow birch, white ash, red oak, American basswood and quaking aspen, along with a handful of softwoods.  

Mass timber is not foolproof, as researchers at the Nature Conservancy and the U.S. Forest Service have pointed out. As a general rule, for example, the further away a construction material from a project site, the less sustainable and more costly it will be to get the product to its final location. 

Too much logging in the name of mass timber can lead to deforestation and habitat loss, and since mass timber is a relatively new product, the researchers are still investigating its total climate impact. Disturbances such as wildfires and diseases could further harm forest health.

Sandra Lupien, who leads a multidisciplinary team as director of the Mass Timber @ MSU project, is working on a supply chain analysis of hardwood CLT’s implications for Michigan, as well as a demand survey for the whole Great Lakes region. While Michigan Tech is focusing on the hard science of hardwood CLT R&D, Michigan State University’s program is working on bringing it and the general principles of mass timber more broadly to the industry. If it reaches its full potential, it could mean a bonanza of new jobs in rural northern Michigan’s lumber yards and managed forests, allowing that part of the state the means to fully embrace the transition to a green construction industry. It will also shorten the distance and therefore transportation emissions necessary to get the CLT to sites in this part of the country. CLT was predominantly developed with softwoods because that was what was available in the region of early adopters in Europe and in the Pacific Northwest.

“The purpose of that work, which is funded by the Michigan Department of Natural Resources, is to help provide the types of insights that prospective manufacturers might want to make mass timber in Michigan would need in order to decide what they need to make, how much, who’s going to buy it, where should they locate, what do they think their workforce and their feedstock chain going to look like?” Lupien said. 

While Michigan remains a big traditional timber state, mass timber production has yet to catch on.

Michigan Democrats gained full control over the governorship and both chambers of the state legislature in the 2022 midterm elections and have advanced clean energy legislation in the intervening years. Governor Gretchen Whitmer has set a goal of producing 60 percent of the state’s electricity sustainably by the end of this decade, and her administration has promoted the use of mass timber in its Healthy Climate Plan. 

“The Michigan DNR has pledged $500,000 over five years to enhance sustainable mass timber construction and manufacturing in the state, aiming to further utilize the $20 billion-plus forest products industry to boost the economy while also working toward achieving net-zero carbon emissions by 2050, as outlined in the MI Healthy Climate Plan,” DNR field analyst Tori Irving told Inside Climate News in an emailed statement. “This continued partnership will support research on potential manufacturers, finding suitable manufacturing locations, and identifying optimal products to meet Michigan’s needs.”

CLT can be more or less expensive than the traditional concrete or steel options, depending on the scale of the project and how it is designed. But Peter Anderson, an architect and partner at San Francisco-based Anderson Anderson, said that because “we’re early in the timber technology environment,” it’s hard to calculate costs.

One issue Anderson envisions for hardwood CLT is that since hardwood is generally more expensive and harder to work with than softwood, the new CLT could have trouble competing. 

“I think that the economics of working with softwood would definitely favor that over hardwood CLT. One factor is that CLT is a very strong technology and hardwood is a much harder wood per size than softwood. At least for smaller projects that are not very dependent on maximum strength, I think that hardwood would be overkill for most of the uses, so you would end up using a larger amount of it,” Anderson said. 

Anderson added that he thought that hardwoods grown in temperate climates may not be suitable in tropical climates like Southeast Asia, where his firm has used some CLT hardwoods. Wood products used in wetter climates must be rot resistant, and temperate hardwoods may not have evolved to withstand it. 

Hardwood CLT is going to be on hold until it is approved by the North American Manufacturing Standard. Berghorn estimates that that timeline would likely be within the next few years. 

“When approval comes, I think it will be good for the economy in the states where you have hardwood in the markets,” Raju Pokharel, a professor of forest economics at MSU, said. “When there’s more demand the prices can go up a little bit, but I don’t think it will have much of an impact [on] wood prices.” 

A macroeconomic analysis produced at Michigan State has found dozens of jobs could be created in the state to meet 2022 demand rates, providing up to $11 million to Michigan’s economy alone, but if demand goes up, there could be much more. As with everything in economics, where you build is what matters.