MASS TIMBER

| A highly adaptable, strong and sustainable. While its combination of structural performance, flexibility in design, and aesthetics are enough for many designers, mass timber has numerous other advantages.

Mass Timber Products

  • Cross-Laminated Timber (CLT)
  • Glued-Laminated Timber (Glulam or GLT)
  • Laminated Veneer Lumber (LVL)
  • Nail-Laminated Timber (NLT)
  • Structural Composite Lumber (SCL)
  • Dowel Laminated Timber (DLT)

TECHNOLOGY

Mass timber products are made by taking smaller wood elements such as strands and connecting them with adhesive, dowels, nails or screws to create longer structural building components. These load-bearing building materials can be used in a wide variety of applications: beams and columns; floor, roof, and wall panels; tall wall framings strider or roof rafters; headers; and more. 

DEVELOPMENT

  • Based at the University of Maine, the Maine Mass Timber Commercialization Center brings together industrial partners, trade organizations, construction firms, architects, and other stakeholders in the region to revitalize and diversify Maine’s forest-based economy by bringing innovative mass timber manufacturing to the State of Maine. The emergence of this new innovation-based industry will result in positive economic impacts on both local and regional economies, particularly in Maine’s rural economies. 
  • Specific objectives include promotion of the siting a mass timber facility in Maine, identifying recommendations to incentivize wider use of mass timber, and promoting possible demonstration projects.

INNOVATION

  • Environmental: Mass timber products use renewable and sustainable resources instead of fossil fuel intensive materials. This equates to a lighter carbon footprint. 
  • Construction: Mass timber construction is faster, leading to less construction traffic, and requires fewer workers than similarly sized concrete construction projects.
  • Seismic Performance: The fact that mass timber weighs less than other materials offers structural advantages such as smaller foundations and lower forces for seismic resistance.
  • Fire Performance: Mass timber provides inherent fire resistance due to the nature of thick timber to char slowly, at a predictable rate, allowing these systems to maintain their structural integrity for significant time durations.

Maine Mass Timber Research

The ASCC tests on lumber from Northeastern U.S. forests and laminated strand lumber (LSL) as hybrid CLT. Findings suggest designing CLT panels with different wood products can optimize laminae attributes, thereby enhancing mechanical and physical properties. Specifically, using LSL as cross-ply material increased perpendicular-to-grain shear strength, significantly boosting panel capacity.

The UMaine researchers qualified two new CLT grades—“E21” and “E21M1” using SPF-S lumber. E21 employs 1650f-1.5E SPF-S MSR lumber in longitudinal layers, while E21M1 uses 2100f-1.8E SPF-S MSR lumber. E21M1 boasts the highest bending properties in the longitudinal direction among PRG 320-listed CLT grades. E21 is comparable to the stiffness and strength of “E2” grade CLT, introducing mechanical competitiveness for CLT manufacturers in Maine and New England globally.

Research at UMaine is currently underway to investigate the effect of gaps between the inner layers on the mechanical properties of CLT. Secondary objectives include the development of modeling techniques applicable to a range of gap sizes to predict said effects, and the determination of whether significant reductions in CLT shear and creep performance, due to the existence of edge gaps of CLT manufactured with lumber, can be mitigated with alternate materials such as SCL.

In 2016, WoodWorks conducted a series of live blast tests on three two-story CLT structures at Tyndall Air Force Base to demonstrate the effectiveness of CLT over a spectrum of blast loads. The University of Maine supported the project by conducting static/quasi-static testing and data analyses and aiding in the design and on-site execution of dynamic blasting.

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