Mass Timber: A Sustainable Game-Changer in Building Construction
Mass timber, a revolutionary construction process that utilizes layered wood as a substitute for traditional materials like concrete and steel, is gaining popularity across the United States, particularly in the Pacific Northwest. This eco-friendly building technique is transforming the industry by addressing carbon emissions associated with construction.
According to the U.S. Environmental Protection Agency, approximately 13% of carbon emissions in the United States are attributed to the construction sector. While efforts have been made to reduce the operational energy of buildings, mass timber focuses on decreasing embodied carbon and emissions during the construction process.
We need to transform our building industry, says Susan Jones, owner and founder of atelierjones LLC, a Seattle-based architecture firm dedicated to mass timber construction. With four buildings under construction, eight already built, and over 20 designs in progress across multiple states, Jones is at the forefront of this movement. She has also authored a book titled Mass Timber: Design and Research.
There are three main types of wood construction: stick frame, solid wood, and mass timber. Stick frame construction is the conventional method for wooden structures, while solid wood construction, which utilizes full logs from old-growth trees, is no longer commonly practiced due to its wastefulness. Mass timber, on the other hand, utilizes state-of-the-art technology to layer and fasten wood products together, resulting in large structural panels, posts, and beams with exceptional strength and versatility.
While some forms of mass timber, like glue or nail-laminated timber, have been used for centuries as a substitute for steel, the advent of cross-laminated timber in the 1990s in Austria catapulted mass timber into larger-scale construction projects. It gained popularity in Europe before spreading to Vancouver, Canada, and more recently, Seattle and Portland.
One of the advantages of mass timber construction is its speed. You can build much faster with mass timber than with any other material, explains Rhys Faler, managing director at the Arcology Institute. The components are manufactured offsite and assembled on the construction site like Lincoln Logs, significantly reducing construction time by two to three months compared to steel and concrete.
In addition to time savings, mass timber construction reduces project costs and carbon emissions due to the lighter weight of wood compared to concrete and steel. Wood is also more readily available and easier to produce than traditional materials, further lowering the environmental and financial impact.
Moreover, mass timber construction contributes to carbon reduction by sequestering carbon within the structures. As Jones explains, When you cut down a tree, the carbon doesn’t just float away. About 30-40% of the carbon stays in the lumber itself. This carbon remains trapped in the wood until the building reaches the end of its lifespan, estimated to be around 150-200 years for mass timber structures.
Contrary to concerns about deforestation, the impact of mass timber construction on logging is minimal. Currently, there are 1,753 mass timber buildings under construction in the United States, indicating a small fraction of the wood supply. However, if mass timber becomes more popular or if countries like China adopt the practice, there may be a need to manage logging practices sustainably.
Addressing fire safety concerns, Faler emphasizes that mass timber is exceptionally fireproof due to the density of the materials. Testing conducted by the U.S. Department of Agriculture confirmed that cross-laminated timber buildings can withstand extreme fire conditions.
While mass timber presents innovative solutions for sustainable construction, it is essential to maintain a balanced perspective. Some critics argue that large-scale timber usage requires significant tree cutting. However, with proper forest management and responsible sourcing, the impact can be minimized.
As the construction industry evolves, mass timber is revolutionizing the way we build tall, eco-friendly structures. Its speed, cost-effectiveness, and carbon reduction benefits are transforming the sector. By harnessing the potential of mass timber, we can create a more sustainable and environmentally friendly future for construction.
