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With advanced construction technologies and modern mass timber products such as glued-laminated timber, cross-laminated timber and structural composite lumber, building tall with wood is not only achievable but already underway – with completed contemporary buildings in Australia, Austria, Switzerland, Germany, Norway and the United Kingdom at 9 storeys and taller. Increasingly recognized by the construction sector as an important, new, and safe construction choice, the reduced carbon footprint and embodied / operational energy performance of these buildings is appealing to communities that are committed to sustainable development and climate change mitigation. Tall wood buildings, built with renewable wood products from sustainably managed forests, have the potential to revolutionize a construction industry increasingly focused on being part of the solution when it comes to urban intensification and environmental impact reduction. The Canadian wood product industry is committed to building on its natural advantage, through the development and demonstration of continuously improving wood-based building products and building systems. A tall wood building is a building over six-storeys in height (top floor is higher than 18 m above grade) that utilizes mass timber elements as a functional component of its structural support system. With advanced construction technologies and modern mass timber products such as glued-laminated timber (glulam), cross-laminated timber (CLT) and structural composite lumber (SCL), building tall with wood is not only achievable but already underway – with completed contemporary buildings in Canada, US, Australia, Austria, Switzerland, Germany, Norway, Sweden, Italy and the United Kingdom at seven-storeys and taller. Tall wood buildings incorporate modern fire suppression and protection systems, along with new technologies for acoustic and thermal performance. Tall wood buildings are commonly employed for residential, commercial and institutional occupancies. Mass timber offers advantages such as improved dimensional stability and better fire performance during construction and occupancy. These new products are also prefabricated and offer tremendous opportunities to improve the speed of erection and quality of construction. Some significant advantages of tall wood buildings include: the ability to build higher in areas of poor soils, as the super structure and foundations are lighter compared to other building materials; quieter to build on site, which means neighbours are less likely to complain and workers are not exposed to high levels of noise; worker safety during construction can be improved with the ability to work off large mass timber floor plates; prefabricated components manufactured to tight tolerances can reduce the duration of construction; tight tolerances in the building structure and building envelope coupled with energy modelling can produce buildings with high operational energy performance, increased air tightness, better indoor air quality and improved human comfort Design criteria for tall wood buildings that should be considered include: an integrated design, approvals and construction strategy, differential shrinkage between dissimilar materials, acoustic performance, behaviour under wind and seismic loads, fire performance (e.g., encapsulating the mass timber elements using gypsum), durability, and construction sequencing to reduce the exposure of wood to the elements. It is important to ensure early involvement by a mass timber supplier that can provide design assistance services that can further reduce manufacturing costs through the optimization of the entire building system and not just individual elements. Even small contributions, in connection designs for example, can make a difference to the speed of erection and overall cost. In addition, mechanical and electrical trades should be invited in a design-assist role at the outset of the project. This allows for a more complete virtual model, additional prefabrication opportunities and quicker installation. Recent case studies of modern tall wood buildings in Canada and around the world showcase the fact that wood is a viable solution for attaining a safe, cost-effective and high-performance tall building. For more information, refer to the following case studies and references: Brock Commons Tall Wood House (Canadian Wood Council) Origine Point-aux-Lievres Ecocondos,Quebec City (Cecobois) Wood Innovation and Design Centre (Canadian Wood Council) Technical Guide for the Design and Construction of Tall Wood Buildings in Canada (FPInnovations) Ontario’s Tall Wood Building Reference (Ministry of Natural Resources and Forestry & Ministry of Municipal Affairs) Summary Report: Survey of International Tall Wood Buildings (Forestry Innovation Investment & Binational Softwood Lumber Council) www.thinkwood.com/building-better/taller-buildings

Tests Current research includes the World’s largest mass timber fire test – click here for updates on the test results currently being conducted https://firetests.cwc.ca/ Studies “The Historical Development of the Building Size Limits in the National Building Code of Canada (17 Mb) “Case Studies of Risk-to-Life due to Fire in Mid- and High-Rise, Combustible and Non-combustible Buildings Using CUrisk“, by Xia Zhang and George Hadjisophocleous of Carleton University, and Jim Mehaffey of CHM Fire Consultants Ltd. (March 2015) (2.3 Mb) “Fire Safety Challenges of Tall Wood Buildings”, by Robert Gerard and David Barber – Arup North America Ltd; Armin Wolski, San Francisco, CA; for the National Fire Protection Association’s Fire Protection Research Foundation (December 2013) “The Case for Tall Wood Buildings – How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures“, by mgb ARCHITECTURE + DESIGN, Equilibrium Consulting, LMDG Ltd, and BTY Group (February 2012) (8.5 Mb) Ontario Tall Wood Reference Guide (8.04 MB) Reports Fire Research Final Report – Full-scale Mass Timber Shaft Demonstration Fire (including the National Research Council test report as an Appendix), by FPInnovations (April 2015) Acoustics Research and Guides RR-331: Guide to calculating airborne sound transmission in buildings (2nd Edition), by the National Research Council (April 2016) Tall Wood Building Demonstration Initiative Test Reports (funding provided by Natural Resources Canada) CLT Diaphragm Properties CLT Firestopping Testing Monotonic Quasi-Static Testing of CLT Connections Shear Modulus of CLT in plan loading Shear Testing of Cross-Laminated Beams Full Scale Exterior Wall Test on Nordic CLT System, by the National Research Council (January 2015) Client Report A1-005991.1 – Fire Endurance of Cross-Laminated Timber Floor and Wall Assemblies for Tall Wood Buildings, by the National Research Council (December 2014) Measurement of Airborne Sound Insulation of Wall & Floor Assemblies Visit Think Wood’s Research Library for additional resources

A stunning coastal forest in Vancouver, BC is the gateway to the University of British Columbia (UBC) which has provided inspiration for the institution’s long-standing relationship with wood. The result is an enviable inventory of wood buildings interspersed throughout the campus which showcases ground-breaking technologies and sustainable design. UBC’s commitment to promoting locally sourced, environmentally responsible, leading-edge engineered wood products and building technologies has culminated in the most recent addition to the UBC Vancouver Campus: the Brock Commons Tallwood House. The newest of the UBC’s student residence buildings, Brock Commons Tallwood House currently stands as the tallest contemporary hybrid mass timber building in the world. Over the years, with an ever-increasing demand for student housing, UBC developed a preferred typology for its student residences, creating mixed-use residential hubs to enhance campus life. For this latest project, the University was determined to demonstrate the applicability of an advanced systems solution to BC’s development and construction industries while advancing its reputation as a hub of sustainable and innovative design. Wood use from the 18th to the early 20th centuries frequently included seven-storey wood buildings; taller wood structures such as church towers and pagodas were built worldwide earlier still. Today, pushing the envelope of wood use comes with challenges. Authorities having jurisdiction and oversight of the approval process for a new generation of tall wood building designs require comprehensive scientific data to evaluate their safety since there are no prescriptive provisions in the Canadian building codes to permit them. Until such a time as building codes establish provisions for tall wood buildings, performance aspects of their design must be proven on a design-by-design basis. Natural Resources Canada (NRCan), in recognition of the technical challenges inherent in the design and construction of modern tall wood structures, has provided targeted funding to support demonstration projects that use innovative engineered wood products and construction systems.

The vulnerability of any building, regardless of the material used, in a fire situation is higher during the construction phase when compared to the susceptibility of the building after it has been completed and occupied. This is because the risks and hazards found on a construction site differ both in nature and potential impact from those in a completed building; and these risks are occurring at a time when the fire prevention elements that are designed to be part of the completed building are not yet in place. For these reasons, construction site fire safety includes some unique challenges. Developing an understanding of these hazards and their potential risks is the first step towards fire prevention and mitigation during the course of construction (CoC).

Courtesy of the Mass Timber Institute There is much to learn from the resilient and adaptable warehouse buildings that line the streets of Canada’s historic manufacturing districts. ‘Historical Tall-Wood Toronto’ is an evidentiary database of late 19th and early 20th century vernacular brick and beam buildings that were built using the fire restrictive specifications and construction technology of Heavy Timber Mill-Construction (mill-construction) in Toronto.

The target audience for this technical resource includes building officials, fire service, architects, engineers, builders, code consultants and developers and other parties involved in the design and approvals of tall wood noted in Table 1 below. This technical resource is expected to help illustrate to applicants how tall wood buildings could be designed as alternative solutions in a way that achieves the level of performance required by Ontario’s Building Code. A tall wood building is defined as a building over six-storeys that uses wood for its structural system and is built using mass timber construction. Mass timber refers to large dimension solid lumber, gluedlaminated lumber, cross-laminated lumber or other large dimension wood products referenced in this technical resource as opposed to conventional stick-frame construction typically used in low-rise and midrise buildings in Ontario. Mass timber offers the advantages of improved dimensional stability and better fire performance during construction and occupancy. Tall wood buildings are not new to Ontario – many such buildings are still in use in Ontario after nearly 100 years in service, however over time, changes to building codes and the introduction of steel and concrete for high-rise construction resulted in a decline in construction of tall wood buildings over the decades. But with new wood products and modern means of fire engineering, modern tall wood buildings are now being built in Canada. The new products and the way in which they are pre-fabricated and constructed offer tremendous opportunities to improve quality and speed of construction for buildings in Ontario. Mass timber products have environmental advantages as well. Trees get their energy from the sun and absorb carbon from the atmosphere. As they grow, trees store carbon and by sustainably harvesting trees, the carbon is sequestered, which helps to reduce greenhouse gas. The carbon stored in wood is not released into the atmosphere when it is harvested. As new trees are planted to replace the harvested trees, the new trees will continue the cycle of carbon storage. Ontario and Canada have significant forest resources which, combined with sustainable forestry management practices, make tall wood buildings an attractive alternate to other materials which do not have these attributes. This technical resource has two main sections: Fire Safety and Structural Design. These two major topics are normally of most concern during design and review of tall wood buildings and are at times interrelated. Thus, it is expected that design teams and building departments will work together at the early stages of design since structural decisions can affect fire performance and vice versa. The sections go into detail on aspects of compliance, methods of analysis, methods of design and the expected performance requirements for fire and structure. Other topics such as thermal performance, acoustic performance and constructability are covered in other references as noted throughout this technical resource.

Acknowledging the growing importance of designing sustainable buildings and addressing overpopulation concerns, the development of engineered wood products has introduced the possibility of constructing high-rise timber structures that can improve both these conditions. However, as a combustible material, one of the biggest barriers to construction of tall timber buildings is the potential fire risk resulting from the combustible structure. In November 2012, the Fire Protection Research Foundation commissioned the Fire Safety Challenges of Tall Wood Buildings study to address this concern. Phase I of this two-phase study seeks to collect the available knowledge of fire safety in timber structures and identify gaps in knowledge that would further the understanding of fire performance of tall timber buildings. Results of the study, including a summary of timber construction and fire dynamics, is presented herein.

Wood is the most significant building material we use today that is grown by the sun. When harvested responsibly, wood is arguably one of the best tools architects and engineers have for reducing greenhouse gas emissions and storing carbon in our buildings. The Case for Tall Wood Buildings expands the discussion of where we will see wood and specifically Mass Timber in the future of the world’s skylines. As we pursue the solar and green energy solutions that Thomas Edison spoke of over 80 years ago, we must consider that we are surrounded by a building material that is manufactured by nature, a material that is renewable, durable and strong. This report introduces a major opportunity for systemic change in the building industry. For the last century there has been no reason to challenge steel and concrete as the essential structural materials of large buildings. Climate change now demands that we do. The work of thousands of scientists with the United Nations Intergovernmental Panel on Climate Change (IPCC) has defined one of the most significant challenges of our time. How we address climate change in buildings is a cornerstone in how the world will tackle the need to reduce emissions of green house gases and indeed find ways to store those same gases that are significantly impacting the health of our planet. Just as the automobile industry, energy sector and most other industries will see innovations that challenge the conventions of the way we will live in this century, the building industry must seek innovation in the fundamental materials that we choose to build with. In a rapidly urbanizing world with an enormous demand to house and shelter billions of people in the upcoming decades we must find solutions for our urban environments that have a lighter climate impact than today’s incumbent major structural materials. This report is a major step in that direction. Indeed it introduces the first significant challenge to steel and concrete in tall buildings since their adoption more than a century ago.