| Highly adaptable, strong and sustainable alternative to concrete.

Research Applications

Qualification of 2 New CLT Grades

  • Researchers at UMaine recently qualified two new grades of CLT using machine stress-rated (MSR) grades of SPF-S lumber. The two grades being evaluated were “E21” utilizing 1650f-1.5E SPF-S MSR lumber in the longitudinal layers and “E21M1” utilizing 2100f-1.8E SPF-S MSR lumber in the longitudinal layers. Both of these grades utilize No. 3 SPF-S lumber in the transverse layers.
  • The E21M1 grade has the highest published bending properties in the longitudinal direction of any CLT grade currently listed in PRG 320. The E21 grade is comparable to “E2” grade CLT, which is manufactured with Douglas-fir, a species known for its high stiffness and strength. Introduction of these grades to those currently available in North America will make manufacturers of CLT in Maine and New England more competitive with other regions domestically and globally.


Cross-laminated timber (CLT) is a mass timber product that is rapidly gaining popularity in the U.S. after being widely adopted in Europe. CLT is the most studied mass timber product and a large focus of ASCC research. 

CLT panels are made of two-by-lumber boards stacked crosswise at 90-degree angles and glued in place. Alternating grains improve CLT performance. The strength, dimensional stability, and rigidity of CLT allow it to be used in mid- and high-rise buildings. For CLT manufacture, availability and access to spruce-pine-fir-south lumber is critical. Within the Northeast, Maine has the highest volume and concentration of accessible spruce-fir and red pine sawlogs. CLT transforms wood that is not usable by itself into sustainable and durable wood building materials.


  • ASCC qualified two new CLT grades using MSR-graded Spruce-Pine-Fir-South (SPF-S) lumber produced in Maine 
  • Recent work at UMaine has demonstrated Maine-grown timber to be an excellent feedstock for CLT production
  • Structural Performance of Hybrid CLT


  • Rapid construction times and improved environmental profiles relative to concrete
  • Lighter compared to other building materials reduces the cost of foundations.
    Can be used for the construction of tall wood buildings of up to 18 stories 
  • The panelized construction method is very quick compared to steel and concrete structures
  • Less waste is created during construction with CLT
  • In a fire, CLT chars naturally and creates a protective outer layer resulting in better performance.

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