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It is significant that wood played such a large role in this type of complex, which is usually done in other materials. The wood structure is a unifying element between the spaces of the centre. The design is coherent, consistent, elegant and expresses wood beautifully.
This case study examines two wood buildings, both with primary retail commercial occupancies, but which employ different mass timber products to achieve very different effects. Askew’s Uptown Supermarket in Salmon Arm, BC, features an expansive nail-laminated timber (NLT) roof that appears to float above the retail floor (Figure 1.1), while the Whistler Community Services Society Building in Whistler, BC, uses a robust, utilitarian exposed glued-laminated timber (glulam) and cross-laminated timber (CLT) structure as befits the building’s industrial setting (Figure 1.2).
In April 2019 John Horgan, Premier of British Columbia, announced a new directive to require municipalities and the BC government to strongly consider the use of wood in public buildings, both as a structural material and for interior finishes. The goal of this initiative is to increase demand for BC’s wood products and to assist the forest industry in dealing with the significant impacts of climate change. To date, these have included the mountain pine beetle infestation and an increase in the frequency and severity of forest fires, both of which have had widespread negative consequences for the industry across the province.
When announcing the initiative, Premier Horgan stated: “We will expect the result to maximize the potential of the existing timber supply, maintain jobs, incorporate First Nations’ interests, and address the economic, cultural, recreational and other uses of BC’s land base.” New engineered mass timber products, supported by new legislation, now make it possible for wood to be used in a wide range of projects, both urban and rural.
This case study showcases two recent projects that illustrate the value and versatility of wood, both in its response to technical challenges and in its contribution to economic and social sustainability in communities around the province.
In Vancouver, Fire Hall No. 5 (Figure 1.1) is an example of an innovative response to rising land costs and the shortage of affordable social housing; while in the Kootenay village of Radium Hot Springs, a wealth of local wood products, manufacturing capabilities and craft skills combine in a community hall and library that can truly be called a ‘100-mile building’ (Figure 1.2).
In 2009, the British Columbia Building Code (BCBC) was amended to permit residential buildings of up to six storeys to be constructed in wood. Since then, through a five-year code process of consultation and research, the potential for expanding these provisions to other building occupancies has been under consideration at the national code level. Changes introduced in the 2015 edition of the National Building Code of Canada (NBC) and adopted in British Columbia in 2018, have expanded these provisions to office-type buildings, but also permit mixed-type occupancies on the first two storeys. As a result, wood building types now include office, residential, mercantile, assembly, low hazard or storage/ garage uses.
This case study examines two wood buildings, both with primary retail commercial occupancies, but which employ different mass timber products to achieve very different effects. Askew’s Uptown Supermarket in Salmon Arm, BC, features an expansive nail-laminated timber (NLT) roof that appears to float above the retail floor (Figure 1.1), while the Whistler Community Services Society Building in Whistler, BC, uses a robust, utilitarian exposed glued-laminated timber (glulam) and cross-laminated timber (CLT) structure as befits the building’s industrial setting (Figure 1.2).
Movement in structures due to environmental condition changes and loads must be considered in design. Temperature changes will cause movement in concrete, steel and masonry structures. For wood materials, movement is primarily related to shrinkage or swelling caused by moisture loss or gain when the moisture content is below 28% (wood fiber saturation point). Other movement in wood structures may also include: settlement (bedding-in movement) due to closing of gaps between members and deformation due to compression loads, including instantaneous elastic deformation and creep. Differential movement can occur where wood frame is connected to rigid components such as masonry cladding, concrete elevator shafts, mechanical services and plumbing, and where mixed wood products such as lumber, timbers, and engineered wood products are used.
Evidence from long-term wood frame construction practices shows that for typical light frame construction up to three storeys high, differential movement can be relatively easily accommodated such as through specifying “S-Dry” lumber. However, differential movement over the height of wood-frame buildings becomes a very important consideration for taller buildings due to its cumulative effect. The APEGBC Technical and Practice Bulletin provides general design guidance and recommends the use of engineered wood products and dimension lumber with 12% moisture content for floor joists to reduce and accommodate differential movement in 5 and 6-storey wood frame buildings. Examples of differential movement concerns and solutions in wood-frame buildings can also be found in the Best Practice Guide published by the Canadian Mortgage and Housing Corporation and the Building Enclosure Design Guide –Wood Frame Multi-Unit Residential Buildings published by the Homeowner Protection Office of BC Housing.
This document illustrates the causes and other basic information related to vertical movement in wood platform frame buildings and recommendations on material handling and construction sequencing to protect wood from rain and reduce the vertical movement.
Most buildings are designed to accommodate a certain range of movement. In design, it is important for designers to identify locations where potential differential movement could affect structural integrity and serviceability, predict the amount of differential movement and develop proper detailing to accommodate it. To allow non-structural materials to be appropriately constructed, estimate of anticipated differential movement should be provided in the design drawings.
Simply specifying wood materials with lower MC at time of delivery does not guarantee that the wood will not get wet on construction sites and will deliver lower shrinkage amounts as anticipated. It is therefore important to ensure that wood does not experience unexpected wetting during storage, transportation and construction. Good construction sequencing also plays an important role in reducing wetting, the consequent wood shrinkage and other moisture-related issues.
Existing documents such as the APEGBC Technical and Practice Bulletin on 5- and 6-Storey Wood Frame Residential Building Projects, the Best Practice Guide published by the Canadian Mortgage and Housing Corporation (CMHC), the Building Enclosure Design Guide – Wood Frame Multi-Unit Residential Buildings published by the BC Housing- Homeowner Protection Office (HPO) provide general design guidance on how to reduce and accommodate differential movement in platform frame construction.
It is not possible or practical to precisely predict the vertical movement of wood structures due to the many factors involved in construction. It is, however, possible to obtain a good estimate of the vertical movement to avoid structural, serviceability, and building envelope problems over the life of the structure.
Typically “S-Dry” and “S-Grn” lumber will continue to lose moisture during storage, transportation and construction as the wood is kept away from liquid water sources and adapts to different atmospheric conditions. For the purpose of shrinkage prediction, it is usually customary to assume an initial moisture content (MC) of 28% for “S-Green” lumber and 19% for “S-Dry” lumber. “KD” lumber is assumed to have an initial MC of 15% in this series of fact sheets.
Different from solid sawn wood products, Engineered Wood Products (EWP) are usually manufactured with MC levels close to or even lower than the equilibrium moisture content (EMC) in service. Plywood, Oriented Strand Board (OSB), Laminated Veneer Lumber (LVL), Laminated Strand Lumber (LSL), and Parallel Strand Lumber (PSL) are usually manufactured at MC levels ranging from 6% to 12%. Engineered wood I-joists are made using kiln dried lumber (usually with moisture content below 15%) or structural composite lumber (such as LVL) flanges and plywood or OSB webs, therefore they are usually drier and have lower shrinkage than typical “S-Dry” lumber floor joists. Glued-laminated timbers (Glulam) are manufactured at MC levels from 11% to 15%, so are the recently-developed Cross-laminated Timbers (CLT). For all these products, low shrinkage can be achieved and sometimes small amounts of swelling can be expected in service if their MC at manufacturing is lower than the service EMC. In order to fully benefit from using these dried products including “S-Dry” lumber and EWP products, care must be taken to prevent them from wetting such as by rain during shipment, storage and construction. EWPs may also have lower shrinkage coefficients than solid wood due to the adhesives used during manufacturing and the more mixed grain orientations in the products, including the use of cross-lamination of veneers (plywood) or lumber (CLT). The APEGBC Technical and Practice Bulletin emphasizes the use of EWP and dimension lumber with 12% moisture content for the critical horizontal members to reduce differential movement in 5 and 6-storey wood frame buildings.
Wood is the only renewable building material within the three major building material types. In exterior applications, wood is subject to deterioration from natural elements and biological attack, but when properly protected, its service life can be extended for many years. The most effective way of protecting exposed wood is the use of wood preservatives. Preserved wood products can have 5 to 10 times the service life of untreated wood. This extension of life saves the equivalent of 12.5% of Canada’s annual log harvests (source durable-wood.com). The preservation of the wood is important, especially when it is specified for use in critical infrastructure applications such as railway ties, bridge timbers, utility poles and guardrail posts for highways. Pressure treated wood ensures that these critical structures remain strong and safe for the duration of their service lives. Pressure treated wood products are also commonly used in agricultural applications such fence rails, posts and building poles, as well as in commercial decks, fences, and other heavy duty outdoor applications. Depending on the required application and the level of protection needed for the wood products, there are a variety pressure treatment methods and approved preservatives that are available in Canada. Pressure treatment is a process that forces preservatives into the wood to protect against fungal decay and destructive insects such as termites and marine borers. In Canada, wood preservatives are registered with Health Canada’s Pest Management Regulatory Agency (PMRA). Individual treating facilities undergo regular environmental assessments and follow the recommendations for the design and operation of wood preservative facilities as outlined in Environment Canada’s Technical Recommendation Document (TRD).
Free technical support for architects, engineers, developers, and builders across Canada designing and building with wood.
WoodWorks provides practical support to project teams exploring wood construction. From early concept and design through to construction completion, the team offers guidance on anything related to the design, engineering and construction of your multi-family and non-residential wood buildings. We’re here to support you with free project assistance, continuing education, and on-demand resources.
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Toronto, ON – The Canadian Wood Council is pleased to announce the winning projects of the 40th annual Wood Design & Building Awards program. This prestigious awards program recognizes and celebrates the outstanding work of architectural professionals from around the world who achieve excellence in wood design and construction.
“We’re proud to recognize leading innovators in wood design through our awards program,” says Martin Richard, Vice President of Communications and Market Development at the Canadian Wood Council. “This year’s submissions were remarkable in their scope, quality, and variety. They reflect a rising interest in biomaterials and highlight the importance of wood as a versatile, low-carbon, high-performance material, driving the next generation of sustainable buildings.”
The jurors for the Wood Design & Building Awards were:
A total of 19 winning projects from a diverse group of creators were selected from the impressive field of entries.
New this year, the regional WoodWorks program awards from Ontario, British Columbia, and Alberta were integrated with the Wood Design & Building Awards.
The jurors for the WoodWorks awards were:
Fifteen winning projects were selected, with five from each regional program. The creativity and talent of these winning teams, as well as the beauty and diversity of their wood projects, are transforming the built environment.
In total, 33 award winners from around the globe were celebrated for excellence in wood design at the Wood Design and Building Awards celebration hosted at the WoodWorks Summit on October 22, 2024.
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