In our history of structural innovations – from ancient Roman aqueducts to cathedrals with soaring rooflines, castles to neighborhoods of mass-manufactured buildings –our construction methods and building efficiencies have refined a great deal. Yet over time, that progress has cost our planet a great deal in non-renewable resources.
A product called Cross Laminated Timber (CLT) has been used in Europe for a couple decades now, and has proven to be a startlingly green alternative to traditional “industrial age” building materials. This engineered wood building system is made from several layers of solid lumber boards, stacked crosswise and bonded together, providing dimensional stability, strength and rigidity.
Replacing concrete and steel with wood as a building material can have a significant impact on reducing greenhouse gas emissions. Unlike other products that deplete the earth’s resources, wood is the only major building material that grows naturally, is renewable, and requires less energy to produce. In fact, wood is the ONLY renewable building material. Using CLT in place of the old standards like steel or concrete is one way to reduce the environmental impact of your structure without compromising on the advances we’ve made in modern structural integrity. Some of the qualities of CLT that make this a solution for the future include:
Durability: With proper design and maintenance, wood structures can provide long and useful service lives equivalent to other building materials. The key is careful planning and understanding of environmental loads and other external factors likely to impact a building over its lifetime.
Strength and Stability: CLT panels form a robust, structurally strong building system that outperforms anything currently available in the USA. Cross lamination provides for superior dimensional stability and offers significant shear strength performance at a very unique weight to strength ratio compared to other common structural materials.
Seismic Resilience: Because of their dimensional stability and rigidity, CLT panels create an effective lateral load resisting system. Researchers have conducted extensive seismic testing on CLT and found panels to perform exceptionally well with no residual deformation, particularly in multi-story applications. In Japan, for example, a seven-story CLT building was tested on the world’s largest shake table. It survived 14 consecutive seismic events with almost no damage. With properly designed connection systems, CLT also offers good ductile behavior and energy dissipation.
Fire Resistance: CLT’s thick cross-section provides valuable and superior fire resistance. Due to its mass, CLT panels char slowly. Once charred, combustion slows and eventually stops as the oxygen source is removed. CLT assemblies also have fewer concealed spaces, which reduces a fire’s ability to spread undetected. CLT structures suffer less degradation than concrete and steel structures in a catastrophic fire event.
Cost Effectiveness: From one-person builders to large construction companies, CLT structural systems will arrive on-site ready to assemble, saving time and money with a swift and accurate building process. Comparing the cost of CLT versus certain concrete, masonry and steel building types and including the advantages of faster construction time and lower foundation costs, the estimated total costs of CLT structures can be very competitive.
Using CLT not only brings environmental benefits, but has additional benefits to construction schedules and design flexibility that make this solution a truly remarkable one. With more and more US-based projects incorporating this new building technology, it is only a matter of time before we can appreciate that all the things we loved about older building technologies are still relevant and important today.
Casey Malmquist, President and General Manager of SmartLam, has served in this position since SmartLam’s inception in January of 2012, and has led the SmartLam team from the ground level to becoming a globally-recognized producer of Cross-Laminated Timber products. Mr. Malmquist has over 30 years’ experience owning and operating a successful construction and development company.