October 17, 2022 - Mass timber: What to know about today’s options for building with wood
Mass timber could be the best-kept secret in Texas. But those familiar with the building material recognize its potential to reshape the way buildings are designed and constructed in the U.S. while promoting healthy forests.
Rob Hughes, Texas Forestry Association Executive Director, said the rising popularity of the building material is a game-changer in the forest industry because it will be used in commercial buildings.
“The commercial buildings markets provide brand new opportunities for forest products to expand beyond their current limited use mostly in single- and multi-family housing,” Hughes said. “Having healthy forested ecosystems is the goal of tree farmers and these new opportunities will allow them to continue providing wood and other environmental benefits that come from sustainably managed forests.”
The usefulness and versatility of one mass timber product could make cross-laminated timber the Swiss Army Knife of this category of wood products. Construction with CLT developed in Europe and is on the rise across the U.S., but to many, it remains unfamiliar. Here are five things to know about the latest trend in sustainable construction.
What is mass timber?
Mass timber is a family of engineered wood products that are solid layers of wood pressed and bonded together. The finished product is stronger than steel and lighter than concrete. Types of mass timber panels include cross-laminated timber, nail-laminated timber and dowel-laminated timber. Applications for each type vary, with expansive possibilities in various types of construction.
“Cross-laminated timber can be used in all of the major structural elements of a building,” said Dr. Aaron Stottlemyer, Texas A&M Forest Service Forest Analytics Department Head. “And mass timber buildings are lighter than concrete or steel buildings, so the foundation doesn’t have to be as extensive or expensive.”
What are the benefits of CLT?
Cross-laminated timber construction has a number of benefits over more conventional construction systems, including a quicker construction time, cost-efficiency, structural strength and environmental sustainability.
“Wood is a quickly renewable resource,” Stottlemyer said. “Unlike conventional steel and concrete building systems, forests are renewable and sustainable.”
Mass timber buildings have a smaller carbon footprint than construction using steel or concrete.
“Steel and concrete construction is energy intensive,” Stottlemyer said. “It takes fossil fuel, and manufacturing steel emits carbon dioxide, while the wood in cross-laminated timber panels stores carbon for the life of the wood, which may be hundreds of years.”
And in addition to being aesthetically pleasing, the exposed wood in mass timber buildings provides physical and mental health benefits. Research has shown that working and living in buildings where you can see exposed wood can relieve stress and help people perform better.
“By building with CLT, it’s providing people with a connection to nature and making the spaces we inhabit healthier and more appealing,” said Stottlemyer.
Is it safe?
The International Building Code allows mass timber construction up to 18 stories tall, approval that came only after extensive testing for structural integrity in fire and seismic conditions as well as blast resistance.
A primary concern for consumers is fire safety, and though wood products are combustible, mass timber has a high degree of fire resistance because of its density.
During fires, mass timber chars on the outside, creating a protective layer that insulates the interior of the wood and slowing combustion of the wood and the spread of the fire.
Testing also demonstrated that mass timber buildings can withstand the impact of a tornado and harsh wind conditions.
“There are places on the coast where there’s a tendency for wind events to have large impact, and there’s potential for CLT to be used to build more resilient buildings,” Stottlemyer said.
Is using more wood good for the forest?
Texas is home to 12 million acres of productive timberland, and the state is growing 30 percent to 40 percent more timber than is harvested each year.
Meanwhile, some of the fastest-growing cities in the state are within reasonable transportation distance of the resource.
“We really have the potential to grow our own cities,” Stottlemyer said. “We have the resources and the demand for the resources. There are sustainability issues with the current methods of construction, and cross-laminated timber has the potential to address many of those issues.”
With more than 90 percent of the state’s forest land privately owned, the lack of strong markets for wood products could mean forest land transitions to other uses.
“The worst thing that could happen to our forests is conversion to non-forest use. When good markets exist, forest landowners are more likely to continue to own the forest and invest in good management,” Stottlemyer said. “Using forests can help maintain forests.”
What comes next?
“We need to get to a point where building owners, developers, design and construction professionals are aware of mass timber, accept it and are willing to build with it,” Stottlemyer said.
That means promoting the benefits of mass timber to the communities of architects, engineers, builders, developers, planners, financial institutions and universities.
“Academic institutions are where innovation happens,” Stottlemyer said. “We also have to teach the future leaders about the value of mass timber.”
Current manufacturing limits the availability of mass timber, particularly cross-laminated timber panels made from southern yellow pine.
“We have the resource and the demand for wood products,” Stottlemyer said. “Our communities and our cities are growing. All of this points to opportunities for existing facilities to increase production as well as the establishment of new manufacturing.”
