Tall wood buildings are gaining momentum around the world
Over the past several years, a number of tall wood projects have been completed around the world, demonstrating successful applications of next-generation lumber and mass timber technologies. Today, the concept is gaining traction in the U.S. – with more architects opting for a sustainable solution for attaining safe, cost-effective, high-performing tall buildings in urban-dense settings.
With more than 17 tall wood buildings of seven stories or more having been built in the past five years, the relevant authorities having jurisdiction, such as building officials, designers, contractors and consumers are more confident than ever in the safety of these buildings.
Wood Buildings are Versatile and Perform
With the right safety measures in place, such as properly installed sprinkler systems, fire-resistance-rated wall, floor and ceiling assemblies, tall wood buildings can be designed to meet and exceed fire safety requirements. Mass timber buildings resist and contain fire, in part due to the inherent nature of the thick, solid panels. Heavy timbers char on the outside while retaining strength, allowing the timber to retain 80 percent of its original strength, slowing combustion and allowing time to evacuate the building. Additional application of protective membrane layers and gypsum board would slow ignition and combustion further. To date, research has demonstrated that solid wood structural elements can be designed to provide a two-hour fire-resistance rating, as is required for taller buildings.
Years of research, real-life events and building code development have also proven that mass timber structures can meet or exceed the most demanding design requirements for wind and seismic situations. Wood is inherently ductile and substantially lighter than steel and concrete, making wood structures better equipped to withstand high wind and seismic forces (*).
Wood buildings are durable and can be designed to last a lifetime. For example, a mass timber system was used in the 1974 rebirth of the nine-story Butler Square Building in Minneapolis. Heavy timber post and beam construction provided an adaptable solution, and has allowed the building to stand strong since 1900.
Wood Buildings Reduce Environmental Impact
When specifying any construction materials, it is important to consider their life cycle environmental impacts. Wood products have less embodied energy and a lighter carbon footprint than many other commonly used building materials. A strong argument can be made for wood’s contributions to reducing the lifetime environmental impact of a building (**).
- Wood is the only building material that sequesters carbon, thus significantly reducing the overall carbon footprint of a project.
- Wood manufacturing requires far less energy and results in fewer greenhouse gas emissions than its major competitors, concrete and steel. A U.S. Forest Service-sponsored LCA study found that using wood in lumber and panel products yields fewer greenhouse gas emissions than other common building materials.
Demand for Wood and Sustainable Management Protect U.S. Forests and Rural Economies
Wood products play a significant role in a modern economy. The U.S. wood products industry employs more than 548,000 people in manufacturing and forestry. U.S. private-forest owners support 2.4 million jobs and $87 billion in payroll. Sustainable forest management practices in the U.S. restrict harvesting levels while maintaining important forest values such as biodiversity and wildlife habitat. In the U.S., the rate of deforestation due to forestry activity has been virtually zero for decades. Since 1952, the growth-removal ratios for both softwood and hardwood show that growth has exceeded harvest.
By making forest sustainability and innovation top priorities, the wood products industry will continue to be a significant employer and supporter of rural economies.
The environmental benefits associated with wood products— renewability, responsible forest practices and a light carbon footprint—are helping to strengthen markets for wood products, in turn stabilizing the wood industry’s ability to create jobs and support local economies.
Strong markets for wood products provide a financial incentive for landowners to invest in their forests and keep them healthy for future generations.
For more information and resources on tall wood buildings, visit www.rethinkwood.com.
** See this US Forest Service study for claims on embodied energy (p. 14), reducing lifetime environmental impact (p. 14), reduction of carbon footprint (p. 17), and wood manufacturing requires less energy to build (p 16)