Reusing Mass Timber: An Investigation of the Opportunities and Challenges

Abstract

Mass timber is becoming more relevant in North America as well as the global design industry. It’s growth in use is due to its sustainability, suitability for prefabrication, and ease of construction. As mass timber is used more and more in new construction, the question of what it means to be “sustainable” is being examined more closely. Issues are being raised about the forest management practices, where the timber is sourced, and what counts as biogenic carbon that is sequestered in mass timber. But there is also the question of the end-of-life scenarios for mass timber that is still largely undetermined. With the average life span of a commercial and multifamily building being approximately 50 years and 50-100 years for a single-family home, little has been studied about the possibilities for reusing mass timber from existing structures. Currently, in some cases, mass timber products cannot be recycled or turned into biomass. This absence of recyclable options is due to the adhesives used in the material and hardware, such as screws, that can break and leave remnants of the hardware that could damage the CNC blade. Instead, the panels and offcuts from production are sent to landfills where they breakdown and release CO2 and methane gases into the atmosphere. The question of how to reuse mass timber products is asked when addressing sustainability and life-cycle assessment. Life-cycle assessment address the life of the product from harvesting, to manufacturing, to building life, and potentially end-of-life reuse to reduce its carbon footprint. Through reuse, mass timber panels can be up cycled (reprocessing the product to have a new use as primary structure) and/or down cycled (the product is used as a secondary structural system or furniture) to continue the life cycle of the product and reduce its carbon impact by continuing benefits of carbon sequestration.