Breakthrough: Eastern Hemlock CLT to Ignite Northeast Boom?

The research has, for the first time, identified timber species in the northeast that can be used in mass timber construction.

Sun 21 Apr 24


Eastern Hemlock holds key to unlocking the US northeastern mass timber potential after a project successfully commercialised cross-laminated timbers made from trees native to eastern America.

Now, the timbers are being used in two projects—the Fairbanks Museum in St Johnsbury, Vermont, and a five-story commercial building at 154 Broadway in Somerville, Massachusetts. Alabama-based Smartlam and Sterling Structural in Phenoix are now producing the timbers at scale – in what is dubbed “a huge step forward” for the industry.

“Public funding has been a catalysed for driving this project,” according to Andy Fast, a Forest Industry Specialist for UNH Cooperative Extension, who noted that “mass timber provides tremendous ecological, societal and economic benefits.”

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152-158 Broadway in Somerville, Massachusetts, is one of two projects currently using eastern hemlock cross-laminated timber in buildings. (Photo Credit: Renders provided by Passive House)

There are 74 known mass timber projects under construction in the New England area (and more than 2,000 across the US), “but no CLT manufacturing facilities east of Chicago…and only one glulam manufacturer in New York State,” according to the project report.

“This gets to the heart of why this project was conceived, to jumpstart the development of mass timber manufacturing in the northeast US by using local softwoods.”

It comes as Wood Central reported a groundbreaking study that projected that demand for mass timber products – across the US – could surge 25 to 40-fold thanks to a surge in nonresidential mid-rise and high-rise construction.

Until now, only timber species from the south and western US and outside the country were available for cross-laminated buildings. 

“Functionally, this is the first time that builders can call a manufacturer and order CLT panels made from Eastern Hemlock,” Charlie Levesque, the Executive Director of North East State Foresters Association, said before adding that researchers have also engineered the first example of Spruce-Pine-Fir cross-laminated timber from the Northeast.

The project, funded by a grant from the US government’s USDA Forest Service, is part of the Eastern Hemlock Cross Laminated Timber Certification and Demonstration Project, overseen by Dr Peffi Clouston, a Professor of Wood Mechanics and Timber Engineering at the University of Massachusetts.

For Dr Clouston, the project has been five years in the making and comes amid a 168% surge in mass timber projects across the Northeast over the past two and a half years – which has seen New York CityBoston and even Havard University turn to cross-laminated timber builds.

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The research team tested the new form of cross-laminated timber as part of a 9-ply sheer capacity transverse test. (Photo Credit: USDA Forest Service)

In the report findings, Dr Clouston notes that while Eastern Hemlock could meet industry standards for CLT, “the current supply chain does not generally supply kiln-dried, planed, and grade stumped lumber to the marketplace….there is also a cost, consideration with the species more expensive comparable to Southern yellow pine.” 

“To meet the requirements (for the PRG-320 standard), all hemlock used as lamstock for CLT must be dried, planned, and grade stamped,” Dr Clouston said before adding that “several major eastern hemlock players have already stepped forward to supply for the project’s testing and pilot.”

Dr Clouston noted that architects, builders and developers had shown a preference for eastern hemlock over spruce-fir, adding that “one architect said that compared to the very light and indistinct spruce-fir and the very yellow, hard look of southern yellow pine, eastern hemlock had a warmer, darker and richer tone.”

“Will this aesthetic preference continue and is strong enough to warrant a price premium over spruce-fir and yellow southern pine? It is too early to know.” However, “over time, as the market and supply chain matures, many barriers should be mitigated, and costs should come down.”

US developers are now using new forms of mass timber, like mass ply panelling to build faster, greener and lighter mid-rise and high-rise buildings across the US. Including the world's first post and plate high-rise in Oakland, California. (Photo Credit: DCI Engineers)
US developers are now using new forms of mass timber, like mass ply panelling, to build faster, greener and lighter mid-rise and high-rise buildings across the US. Including the world’s first post and plate high-rise in Oakland, California. (Photo Credit: DCI Engineers)

Last month, Wood Central reported that demand for mass timber buildings could grow 10-20 times in the Northeast over the next 50 years, primarily driven by government policy and adoption curves.

Under the optimal scenario, the researchers predict that mass timber consumption will grow 452 million cubic metres to 750 million cubic metres over the 50-year projected period, with “the greatest adoption rates projected for the seven-stories and higher,” fuelled by a surge in new buildings in the American South (43%), followed by the West (23%), the Midwest (21%) and the Northeast (13%).


  • Jason Ross

    Jason Ross, publisher, is a 15-year professional in building and construction, connecting with more than 400 specifiers. A Gottstein Fellowship recipient, he is passionate about growing the market for wood-based information. Jason is Wood Central's in-house emcee and is available for corporate host and MC services.


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