Advances in Mass Timber and the Role of Wood in Modern Construction

Wood is one of humanity’s oldest, most reliable, and most versatile materials. From the flames of our first fires to the frame of our first aircraft, wood has remained one of our most steadfast assets. Industrial progress has moved us away from this renewable and accessible material towards a society built around metal, cement, and plastic. These modern materials provide many advantages over wood, but they also bring their share of drawbacks. As we continue to move towards a more balanced relationship with our environment and resource consumption, mass timber allows us to reemphasize the importance of wood in the construction sector.

Mass timber, also called engineered wood, entails planks of wood fastened together with nails, resin, or wood plugs to increase strength and stability. Many variants of mass timber exist, depending on the orientation of the planks and the material used to secure them. The two most promising variants are cross-laminated timber (CLT) and glue-laminated timber (Glulam). CLT is made by stacking alternating layers of planks and fixing them together with interlocking joints and glue. It is stable enough to act as floor and wall paneling. Glulam is made by non alternating layers of planks fixed together with glue and is best used for columns and beams.  

CLT and Glulam were first perfected by an Austrian joint government-industry research effort in the 1990s.  Since then, the materials have made steady gains throughout the European construction sector. While still mostly concentrated in Europe, mass timber has begun to make inroads across the globe. Many emphasize the environmental benefits of the material, but less acknowledged are the practical and cost advantages that have motivated its spread.

Perhaps mass timber’s greatest advantage compared to concrete and steel is its weight. Without sacrificing structural stability, mass timber buildings weigh between one-third and one-fifth of a traditional building. By increasing how much material a crew can move per hour, this weight reduction allows mass timber crews to work faster and with smaller teams. A 2016 study found that mass timber construction had a total build time 61 percent shorter than a similarly sized traditional building. Another benefit from this reduced weight is the ability to construct larger buildings on weight-sensitive terrain.  From urban areas with underground transportation networks to coastal regions with soft, marshy ground, mass timber can allow for taller projects.  

An oft-cited concern is mass timber’s performance during a fire. Despite being solid wood, recent US Forest Service testing confirmed that Glulam and CLT retain structural integrity during building fires for up to three hours, an hour more than the required minimum to meet code requirements. The outer layer chars quickly, insulating inner layers against direct exposure to flames. While the wood will ultimately burn through if the fire goes uncontained, the charring affords time for a building to be evacuated.

Even with these promising advantages, mass timber utilization in the U.S. has remained low. While many are optimistic about the material’s ability to revolutionize the American construction sector, adoption has been limited. About 2,400 non-residential mass timber buildings exist in the U.S., an underwhelming figure when compared to the 5.9 million non-residential buildings constructed in 2019 alone. The two factors which have most limited this adoption are quite simple but daunting: price and accessibility.  

There is no firm academic consensus on the price of mass timber construction compared to steel and concrete. While a majority of studies have confirmed that mass timber is 2.5 percent to 6 percent more expensive than traditional options, others have concluded that mass timber can be up to 10 percent cheaper. This divergence appears to be based on both the construction’s proximity to a mass timber production facility and the weight attributed to opportunity costs by the researchers. Often, when researchers find that mass timber construction is lower-cost, it is because they attach more value to the time and work crew reductions. While this approach is sound from an economic perspective, the reality is that mass timber most often has a higher price tag, which naturally deters constructors from making the switch.  

Accessibility remains another serious limitation on mass timber adoption. When assessing mass timber’s lackluster market share, the Congressional Research Service identified “unfamiliarity within the construction community” as a major limiting factor to adoption. A 2020 survey found that 73 percent of builders in the U.S. felt that mass timber was “somewhat inaccessible,” compared to traditional materials, which are permanently accessible. A combination of lack of awareness and limited mass timber distributors in the United States compound to drive down consumption of the material outside of specific areas.

It is in these specific areas that deploy mass timber at scale that the solution for expanding utilization in the U.S. can be found. Individual municipalities like Boston, states like Washington, and firms like the Softwood Lumber Board all contribute to mass timber accelerator programs. These programs work to establish production facilities, increase local awareness, and subsidize mass timber construction.  

Nationwide funding, while it does exist, is limited and expanding. Any drastic increases would likely be met with political pushback. Instead, relying on small-scale funding efforts by groups intrinsically motivated to spread, mass timber will be the most realistic path forward for the material’s continued spread. The material possesses many advantages, notably weight, and has overcome its greatest limitation, fire resistance. Now it will compete in the market naturally, likely not rapidly revolutionizing U.S. construction but slowly integrating over the coming years. 

Innovation is a high tide that raises all boats. With enough time and investment, innovation elevates materials, processes, and techniques to new heights of efficiency and application. Compared to 1920, farmers in the United States today use 100 million less acres of land to feed a population that has more than tripled. The sand that once made only glassware now also forms the silicon wafers so critical to modern computers. Mass timber promises bring wood to this level of modernity, first in contained localities with the potential to grow from there.

Written by Colson Grimes, Public Policy Intern