Cross‑laminated timbers made from American hardwoods could be up to three times stronger and significantly stiffer than panels made from southern yellow pine. The material can produce longer, thinner panels well-suited to mid- and high-rise construction. That is according to a study published in the Journal of Forestry, which found that hardwood CLT could open new markets for rural mills and eastern U.S. hardwood producers if it can overcome higher costs, technical hurdles, and the lack of structural grading.
The research, published in late November, interviewed sawmills, engineers, architects and wood scientists to understand the technical, economic and social viability of hardwood CLT. Led by the University of Tennessee and the USDA Forest Service, it found that hardwood panels offer standout mechanical performance, with compression strengths “up to three times higher than southern yellow pine” and stiffness gains of more than 300 per cent when moving from three‑ply to five‑ply configurations.
The study also highlights the aesthetic appeal of hardwoods.
Red and white oak were identified as strong candidates for exposed‑timber applications, and several participants pointed to hybrid panels that combine softwood cores with hardwood outer layers – an approach that could deliver a competitive price whilst maintaining aesthetic appeal.
Last year, Wood Central reported that a growing number of American hardwoods are being used in ‘niche’ mass timber applications, with architects leaning on Red oak, White oak and Tulipwood to build some of the world’s most famous projects. And whilst it’s unlikely it will “get the jump on softwoods,” Rod Wiles of the American Hardwood Export Council (AHEC) said hardwoods do have advantages:
“For cross‑laminated timber made out of Tulipwood, you need much less wood, much less material, to make panels just as strong,” You may only need five layers of Tulipwood in a panel, instead of seven for a softwood panel, given Tulipwood is three times stronger in rolling shear… and the same goes for Red oak and glulam.”
Rod Wiles, Regional Director for the American Hardwood Export Council (AHEC) in Africa, the Middle East, India and Oceania who spoke to Wood Central about the advantages of hardwoods in mass timber.
Manufactured by Hess Timber, it features 11 cantilevered White oak beams – the longest measuring 23.4 metres, making them (for the time) the longest glue-laminated beams manufactured in Europe.
Despite growing momentum, hardwood CLT remains more expensive to produce than softwood CLT. That’s because hardwoods are typically two to three times the price of softwoods, although the study notes that lower‑grade species such as poplar, ash and maple can meet ANSI and APA PRG 320 standards at a lower cost. Researchers say this could help bring hardwood CLT within reach of the commercial market.
As it stands, hardwood is plentiful across the eastern United States, but demand in traditional markets such as furniture and flooring has been falling for years, leading producers to seek new outlets. “Subsidies are helpful in the beginning,” one engineer said, “but the industry must be self‑sustaining once they end.”
The study also points to several structural barriers holding back adoption. Hardwood lumber is still graded mainly for appearance under National Hardwood Lumber Association rules, and few graders are trained to assess structural performance. Many sawmills also lack the scanning and testing equipment required under the PRG 320 guidelines, limiting their ability to certify hardwood for structural use.
One development could help shift that. Yellow poplar was under consideration for inclusion in the 2025 edition of the PRG 320 standard at the time of the interviews, a step respondents described as key toward broader code recognition. One participant highlighted TimberKraft’s plans for a hardwood CLT plant in Virginia once the approval process is complete, calling it a potential spark for wider market uptake.
At the same time, liability and insurance issues were also raised. Sawmill owners told researchers they don’t carry builder’s risk or product‑liability coverage for structural materials. Some experts said more research is needed on decay and moisture resistance, although wood scientists interviewed for the study believe hardwood CLT could achieve two‑hour fire ratings because of its predictable burn characteristics.
- To learn more about Rod Wiles and AHEC, the global face of the US hardwood industry for over thirty years, click here to watch Wood Central’s podcast in full.
