This article was published under Sustainable Communities: Thought Leadership on SaportaReport on February 26, 2018.
The City of Portland will soon be home to the country’s tallest mass timber building. Scheduled to be completed in 2018, the Framework – as the building has been called – will be a soaring twelve-story tall mixed-use development that sheds light on the growing interest in wood as construction material in non-traditional projects.
According to the American Wood Council, mass timber is the “category of framing styles typically characterized by use of large solid wood panels for wall, floor, and roof construction.” Most mass timber projects use glue-laminated timber (glulam), cross-laminated timber (CLT), and nail-laminated timber (NLT) as the main load-bearing structural components of a building, rather than concrete or steel beams. As their names suggest, these timber products incorporate glues or nails to adhere multiple wood panels together (either on their edge or in a crisscross pattern) in order to create solid, structural panels that rival the strength and rigidity of their more conventional counterparts.
Mass timber projects like the Framework have not been very prevalent in the United States. However, recent studies have shown that building with wood can lead to large positive effects in overall carbon reduction. In fact, the practice of wood construction was recently included in a list of 100 strategies outlined by Project Drawdown, a climate change mitigation initiative started by Paul Hawken and Amanda Joy Ravenhill that can lead to an overall decrease in total atmospheric carbon.
While wood construction is quite common at the residential level, steel and concrete have been the materials of choice for high-rise and commercial projects. Additionally, national and regional building codes have also been a hurdle for the widespread adoption of mass timber, which often site fire and structural safety concerns as reasons for not allowing glulam or CLT to be used in projects over a certain height.
Mass timber, however, is quickly becoming a more popular alternative to traditional high-rise building construction materials around the world. Cities, businesses and industry leaders are taking a closer look at the economic and environmental benefits that wood construction and mass timber bring to projects and climate change mitigation.
While some opponents may see the mass timber industry as damaging to the ecological integrity of the world’s valued forests, it’s important to differentiate between inefficient logging practices and the production of mass timber products. Logging is often the unceremonious, indiscriminate act of tree removal that has resulted in rampant rates of deforestation around the world. Products like CLT, however, use material from trees grown in sustainably managed forests. And though some may argue that tree removal will reduce overall carbon sequestration from the atmosphere, sustainably managed forests actively promote tree growth which ultimately increases the potential for carbon sequestration.
In 2014, a study out of Yale University found that using more wood in construction projects would have a profoundly positive effect on global greenhouse gas emissions and climate change mitigation. In fact, according to the study, building with wood as opposed to concrete or steel could reduce annual global emissions of carbon dioxide by 14-31%. Additionally, global fossil fuel consumption could see a 12-19% reduction. The manufacturing of construction materials like steel beams requires roughly ten times more fossil fuels than the manufacturing of CLT.
What may be even more relevant and pertinent for construction teams is the dramatic reduction in overall construction time when projects incorporate glulam or CLT. As Project Drawdown notes, mass timber products can be prefabricated, which allows these structural panels to be quickly assembled and attached to one another, decreasing construction periods and minimizing overall disruption on a local community. It should also be noted that when exposed to fire, the exterior of mass timber products char and form a protective layer for the building’s overall structural integrity.
Though mass timber is not yet a popular construction method, it is gaining traction in key global markets. Last fall, the Canadian government announced its push for a new mass timber construction program that would help the country reduce its overall carbon footprint and achieve its goals that were outlined under the Paris Agreement. It may not be long before major cities across the United States start to more fully incorporate wood construction in high-rise developments as a displayed commitment to carbon reduction and climate change mitigation.
