Sustainable Northwest (SNW) and Hacienda Community Development Group (HCDC), both based in Oregon, have proposed a plan to demonstrate pathways for building affordable housing with regionally sourced mass timber. In response to the region’s housing shortage, the partners’ proposal demonstrates the use of mass timber products while supporting efforts to educate stakeholders on wood product companies and forest restoration. The project outlines a plan to explore financing options, build one or more prototypes, and perform a structural material life cycle analysis.
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).
Mass timber construction in Canada is in the spotlight and emerging as a sustainable building system that offers an opportunity to optimize the value of every tree harvested and to revitalize a declining forest industry, while providing climate mitigation solutions. Little research has been conducted, however, to identify the mass timber research priorities of end users, barriers to adoption and engineering, procurement and construction challenges in Canada. This study helps bridge these gaps. The study also created an interactive, three-dimensional GIS map displaying mass timber projects across North America, as an attempt to offer a helpful tool to practitioners, researchers and students, and fill a gap in existing knowledge sharing. The study findings, based on a web-based survey of mass timber end users, suggest the need for more research on (a) total project cost comparisons with concrete and steel, (b) hybrid systems and (c) mass timber building construction methods and guidelines. The most important barriers for successful adoption are (a) misconceptions about mass timber with respect to fire and building longevity, (b) high and uncertain insurance premiums, (c) higher cost of mass timber products compared to concrete and steel, and (d) resistance to changing from concrete and steel. In terms of challenges: (a) building code compliance and regulations, (b) design permits and approvals, and (c) insufficient design experts in the market are rated by study participants as the most pressing “engineering” challenge. The top procurement challenges are (a) too few manufactures and suppliers, (b) long distance transportation, and (c) supply and demand gaps. The most important construction challenges are (a) inadequate skilled workforce, (b) inadequate specialized subcontractors, and (c) excessive moisture exposure during construction.
Timber has been considered as a promising building material because of its structural rigidity, environmental sustainability, and renewability nature. In Europe and Australia, timber materials have been used for many different types of construction such as residential, commercial, education, and industrial. However, in the U.S., the familiarity of timber products is gaining momentum. The construction practitioners are still reluctant to consider mass timber as a mainstream building material. A limited number of case study projects make it difficult for industry personnel to evaluate the actual construction feasibility of mass timber. As a result, a significant knowledge gap has been created that hindering the progress of mass timber material in the U.S. construction industry. To help solve the problem, this study aims to identify the existing awareness level among the U.S. building constructors regarding mass timber building materials. It further determines some of the major construction-related difficulties of mass timber buildings and recommendations overcome those difficulties to increase the acceptance of this material. The study performed a semi-structured questionnaire survey to carry out statistical analysis regarding mass timber building material. Analysis of descriptive statistics suggested that the level of awareness and involvement by the U.S. construction practitioners in mass timber building is still significantly low as 55% of the participants indicated no experience on mass timber building construction projects. Qualitative data analysis suggested that lack of experience in timber construction, poor coordination among the project parties, design-related difficulties, and high cost of mass timber panels are the biggest construction-related barriers to adopt this product. To overcome the existing difficulties, the study proposed an increasing number of timber building projects and manufacturing plants, effective early collaboration among the project parties, developing skilled workers, and a nation-wide promotion by the owners and the architects. The outcomes of this study will be helpful for the industry practitioners and the owners to adopt mass timber as a mainstream building material. The study will further increase the acceptance of this material in the U.S. construction industry.
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.
This report explores the building code related considerations of wood construction for school buildings that are up to four storeys in height. Though wood construction offers a viable structural material option for these buildings, the British Columbia Building Code (BCBC 2018) currently limits schools comprised of wood construction to a maximum of two storeys. Three- and four-storey schools and larger floor areas in wood construction require an Alternative Solution.
The report identifies key fire safety features offered by combustible construction materials including tested and currently widely available engineered mass timber products, such as glued-laminated timber and cross-laminated timber. A risk analysis identifies the risk areas defined by the objectives of the British Columbia Building Code (BCBC 2018) and evaluates the level of performance of the Building Code solutions for assembly occupancies vis-à-vis the level of performance offered by the proposed schools up to four storeys in building height.
As land values continue to rise, particularly in higher-density urban environments, schools with smaller footprints will become increasingly more necessary to satisfy enrollment demands. There are currently a number of planned new school projects throughout British Columbia that anticipate requiring either three-or four-storey buildings, and it is forecasted that the demand for school buildings of this size will continue to rise.
This report is closely related to the study Design Options for Three-and Four-Storey Wood School Buildings in British Columbia, which illustrates the range of possible timber construction approaches for school buildings that are up to four storeys in height.
This research was conducted to discover how the U.S. building construction and forest products sectors could benefit from the development of tall, cross-laminated (CLT) and mass timber buildings. Barriers that may restrict such development were also investigated. The primary benefits were discovered to be eco-performance and job creation. Code restrictions and material performance misconceptions were found to be the largest obstacles. Case studies of Treet, Tamedia, and the WIDC were conducted to demonstrate the benefits of tall wood buildings and the various paths around potential barriers. Opportunities for tall wood buildings in the U.S. are also discussed. This research discovered that a tall wood movement is gathering momentum in the U.S. To fully realize this potential, accurate information regarding the use of wood and the performance capacities of mass timber systems needs to be disseminated. Co-operation between academia and industry will also be necessary.