Project contact is Lech Muszynski, Oregon State University College of Forestry
This research is a continuation of a long-term effort of systematically monitoring developments in the global CLT industry launched by the PI in 2011 and since 2017 partially funded by an ARS/TDI grant.
Overall, including research conducted before ARS funding, this effort has involved two surveys launched in 2016 and in 2019; 46 targeted site tours of CLT manufacturing lines located in the USA, Japan, Australia, New Zealand, China, France, Germany, Norway, Sweden, Finland, and Estonia; and an extensive review of trade journals tracking the development of the CLT industry. While adhesive-bonded CLT remains the main focus of the research, beginning with 2017 the survey also included two related mass timber panel (MTP) products classified as glueless CLT (massive cross-laminated timber panels bonded with nails and hardwood dowels), MTP hardware manufacturers, construction sites and research laboratories concerned with MTP related research.
To-date we have created and populated a unique database covering more than 116 manufacturing plants (including more than 60 CLT lines) across the globe. The database includes information on MTP manufacturers within and outside the MTP industry cluster, including: changes in production capacity and dominant technologies in global MTP production; key success factors and constraints determining the emergence and growth of production; differences in perception of opportunities, risks, challenges and constraints; related business models, strategies, contextual policies, and; the role of innovation systems.
The purpose of the study is to evaluate and summarize any technical or other impediments to using hem-fir in mass timber products. The different mass timber products included in the study are cross-laminated timber (CLT), glue-laminated timber (glulam), dowel-laminated timber (DLT) and nail-laminated timber (NLT).
Nail-Laminated Timber (NLT) and box beam are efficient and economical engineered wood products. Although NLT has been used in North America for more than a century, only in recent years it has gained renewed interests as they have been seen as the most economical panel products used in mass timber buildings. Box beams, on the other hand, are lightweight and generally possess higher strength and stiffness than comparable-sized solid timber and are more efficient than solid timber large spans and loads.
In this report, existing design provisions and their limitations for the design and construction of NLT in box beam in Canadian standards are reviewed. For NLT, there is a general lack of information related to manufacturing, design and construction to ensure consistent manufacturing and installation practices. Therefore, it is difficult to research and document with confidence the full range of performance that can be achieved with NLT. It is therefore recommended that a North American product standard and design information on structural performance, floor vibration, fire resistance, acoustic performance, and construction risk mitigation measures (e.g. moisture and fire) be developed.
In CSA 086, design methods are limited to box beams with flanges and webs bonded with glue. As the flanges and webs of a box beam can be assembled by either glue or mechanical fasteners, it is recommended that design provisions for box beam with mechanical joints be also developed. With the information in Eurocode 5 and relevant supporting research papers, it is ready to be implemented.
The development of this primer commenced shortly after the 2018 launch of the Mass Timber Institute (MTI) centered at the University of Toronto. Funding for this publication was generously provided by the Ontario Ministry of Natural Resources and Forestry. Although numerous jurisdictions have established design guides for tall mass timber buildings, architects and engineers often do not have access to the specialized building science knowledge required to deliver well performing mass timber buildings. MTI worked collaboratively with industry, design professionals, academia, researchers and code experts to develop the scope and content of this mass timber building science primer. Although provincially funded, the broader Canadian context underlying this publication was viewed as the most appropriate means of advancing Ontario’s nascent mass timber building industry. This publication also extends beyond Canada and is based on universally applicable principles of building science and how these principles may be used anywhere in all aspects of mass timber building technology. Specifically, these guidelines were developed to guide stakeholders in selecting and implementing appropriate building science practices and protocols to ensure the acceptable life cycle performance of mass timber buildings. It is essential that each representative stakeholder, developer/owner, architect/engineer, supplier, constructor, wood erector, building official, insurer, and facility manager, understand these principles and how to apply them during the design, procurement, construction and in-service phases before embarking on a mass timber building project.
When mass timber building technology has enjoyed the same degree of penetration as steel and concrete, this primer will be long outdated and its constituent concepts will have been baked into the training and education of design professionals and all those who fabricate, construct, maintain and manage mass timber buildings.
One of the most important reasons this publication was developed was to identify gaps in building science knowledge related to mass timber buildings and hopefully to address these gaps with appropriate research, development and demonstration programs. The mass timber building industry in Canada is still a collection of seedlings that continue to grow and as such they deserve the stewardship of the best available building science knowledge to sustain them until such time as they become a forest that can fend for itself.