Mass Timber Revolution

Architects, structural engineers, and material scientists are leading a global revolution in our understanding of how to use wood to create large-scale buildings of up to thirty stories tall. Many of us harbor a set of assumptions about wood that may require re-examination. For example, we expect that wood may be useful for small buildings, or for houses up to two or three stories, but not strong enough for larger, taller, or more substantial structures. We believe that wood buildings are inherently more susceptible to fire than steel or concrete. We know that live trees sequester carbon, that it takes up to 50 years for many tree species to grow to maturity, so we worry about whether harvesting timber can be sustainable.

The landscape for our discussion of using timber as a way to sequester large quantities of carbon in the built environment has been reshaped by recent advances in technology, engineering and safety. It’s now possible to build much taller wood buildings using newly-developed mass timber products.

Cross-laminated Timber (CLT)
 

These include cross-laminated timber and nail-laminated timber for major structural components, and glue laminated timber panels for floor and wall framing. All three of these new forms of timber are created by combining smaller pieces of wood into much larger, much stronger, and much more fire-resistant shapes. Mass timber products can be built from trees that are small in diameter, fast-growing, and sustainably harvested. Best of all, timber that has been cured and processed contains close to 50% carbon, so wooden buildings can sequester quantities of carbon semi-permanently.

Mass Timber construction of an office building

According to reThink Wood, mass timber products:

  • are cost-competitive, carbon efficient, sustainable and reliable.
  • complement existing light frame and heavy timber options.
  • are suitable candidates for some construction applications that currently use concrete, masonry and steel.
  • stem from the results of scientific information and data generated from full scale fire, seismic, durability, acoustic and vibration tests being conducted internationally by researchers and engineers.
  • make taller mass timber, wood-concrete and wood-steel-hybrid buildings a reality.

Also according to reThink Wood, an impressive number of multi-story office and commercial buildings have sprung up around the world in recent years:

 

Finally, Congressperson Suzan Delbene (D-WA) together with her co-sponsors in both houses of Congress and from both parties, has introduced the Timber Innovation Act in order to promote the research and development needed to expand the sustainable use of wood throughout the construction industry, especially in tall buildings.