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This document is a Design example of Stacked Multi-Storey Wood Shearwalls Using A Mechanics Based Approach. It shows a floor plan and elevation along with the preliminary shear wall locations for a six=storey wood-frame building. It is assumed some preliminary calculations have been provided to determine the approximate length of wall required to resist the lateral seismic loads.
As the design and construction industry collectively strives towards a more sustainable built environment, one of the more interesting challenges in architecture today is how to work with what already exists. When existing structures are adapted and repurposed rather than demolished once they outlive their original use, resources are conserved, greenhouse gas emissions are lowered, heritage is preserved, and decarbonization goals are advanced.
Whether it’s adapting a historic structure to a new use or extending the life of a contemporary one with a creative renovation or addition, designers are exploring the possibilities and finding ways to integrate wood into projects that build on the foundations of the past, figuratively and literally, to meet the needs of the present.
In this issue, two feature stories explore different approaches to giving existing buildings new, expanded purpose. One project breathes new life into a traditional fieldstone barn through adaptive reuse, while another demonstrates how a lightweight mass timber vertical addition can expand an existing apartment building, adding new units to help meet growing housing needs. Both illustrate how wood enables design solutions that are respectful, efficient, and forward-looking.
Projects like these remind us that innovation is a form of evolution, and sometimes, the most sustainable, creative, and community-minded choice is to work with what you’ve already got.
The vulnerability of any building 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 and hazards are occurring at a time when the fire prevention and protection 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. However, an understanding of the hazards and their potential risks is the first step towards fire prevention and mitigation.
It is important to comply with applicable regulations related to fire safety planning during construction, and cooperation between all stakeholders in establishing and implementing a plan goes a long way in reducing the potential risk and impacts of a fire on any construction sites. In addition to province-wide regulations, local governments and municipalities can also have specific laws, regulations or requirements that must be followed. The local fire department can be a resource in directing you to these additional regulations or requirements.
Construction site safety has the potential to impact productivity and profitability at any phase of the project. Given that provincial or municipal regulations provide the minimum requirements for construction site fire safety, consideration should also be given to the specific characteristics, objectives and goals of the project, which could provide incentives to exceed the regulated standards for construction site fire safety. It can be prudent to assess and implement various ‘best practices’, based on the specific needs of your site, which can provide an additional level of protection and build a culture of fire safety.
Most construction site fires can be prevented with knowledge, planning and diligence; and, the impact of those fires that might occur can be significantly lessened. Understanding and addressing both the general and specific hazards and risks of a particular construction site requires education and training, as well as preparedness and continued vigilance.
For further information, refer to the following resources:
For many years, the design values of Canadian dimension lumber were determined by testing small clear samples. Although this approach had worked well in the past, there were some indications that it did not always provide an accurate reflection of how a full-sized member would behave in service.
Beginning in the 1970s, new data was gathered on full-size graded lumber, known as in-grade testing. In the early 1980s, the Canadian lumber industry conducted a major research program through the Canadian Wood Council Lumber Properties Program for bending, tension and compression parallel to grain strength properties of 38 mm thick (nominal 2 in) dimension lumber of all commercially important Canadian species groups. The Lumber Properties Program was conducted as a cooperative project with the US industry with the goal of verifying lumber grading correlation from mill to mill, from region to region, and between Canada and the United States.
The in-grade testing program involved testing thousands of pieces of dimension lumber to destruction in order to determine their in-service characteristics. It was agreed that this testing program should simulate, as closely as possible, the structural end use conditions to which the lumber would be subjected to.
After the test samples were conditioned to approximately 15 percent moisture content, they were tested under short- and long-term loading in accordance with ASTM D4761. Lumber samples in three sizes; 38 x 89 mm, 38 x 184 mm and 38 x 235 mm (2 x 4 in, 2 x 8 in, and 2 x 10 in), were selected across the Canadian growing regions for the three largest-volume commercial species groups; Spruce-Pine-Fir (S-P-F), Douglas Fir-Larch (D.Fir-L) and Hem-Fir. Select Structural, No.1, No.2, No.3, as well as light framing grades, were sampled in flexure. Select Structural, No.1 and No.2 grades were evaluated in tension and compression parallel to grain. Several lesser-volume species were also evaluated at lower sampling intensities.
The in-grade testing resulted in new relationships between species, sizes and grades. The dimension lumber database of results was examined to establish trends in bending, tension and compression parallel to grain property relationships as affected by member size and grade. These studies provided a basis for extending the results to the full range of dimension lumber grades and member sizes described in CSA O86. In Canada, both the CSA O86 and the National Building Code of Canada (NBC) have adopted the results from the Lumber Properties Program. The data has also been used to update the design values in the United States.
The scientific data resulting from the Lumber Properties Program demonstrated:
Following the testing program, the consensus-based ASTM D1990 standard was developed and published. Data for bending, tension parallel to grain, compression parallel to grain, and modulus of elasticity continue to be analyzed in accordance with this Standard.
Unlike visually graded lumber where the anticipated strength properties are determined from assessing a piece on the basis of visual appearance and presence of defects such as knots, wane or slope of grain, the strength characteristics of machine stress-rated (MSR) lumber are determined by applying forces to a member and actually measuring the stiffness of a particular piece. As lumber is fed continuously into the mechanical evaluating equipment, stiffness is measured and recorded by a small computer, and strength is assessed by correlation methods. MSR grading can be accomplished at speeds up to 365 m (1000 ft) per minute, including the affixing of an MSR grade mark. MSR lumber is also visually checked for properties other than stiffness which might affect the suitability of a given piece. Given that the stiffness of each piece is measured individually and strength is measured on select pieces through a quality control program, MSR lumber can be assigned higher specified design strengths than visually graded dimension lumber.
For further information, refer to the following resources:
Canadian Lumber Properties (Canadian Wood Council)
ASTM D1990 Standard Practice for Establishing Allowable Properties for Visually-Graded Dimension Lumber from In-Grade Tests of Full-Size Specimens
ASTM D4761 Standard Test Methods for Mechanical Properties of Lumber and Wood-Based Structural Materials
National Lumber Grades Authority (NLGA)
“Durability by design” is the most important aspect of durable solutions. It starts with using dry wood, storing it appropriately to ensure it stays dry, and then designing the building to protect the wood or, if the wood will be exposed, designing to not accumulate moisture. It includes ensuring the building envelope is appropriately designed to shed bulk water, mitigating water and vapour from getting into the envelope, and draining water that does leak into the envelope.
Tall Wood Feasibility Study: Mass Timber and Concrete explores the economic, construction, and environmental performance of a proposed 12-storey residential development in Dartmouth, Nova Scotia.
Developed through a side-by-side comparison of optimized mass timber and concrete schemes, this study examines how material choice influences project cost, schedule, financial returns, and embodied carbon. Beyond a direct cost comparison, it provides insight into how mass timber can support construction efficiency, earlier occupancy, long-term asset value, and meaningful product differentiation in the rental market.
The publication includes detailed analysis of design strategy, risk mitigation, development economics, scheduling, and structural carbon impacts—offering developers, investors, designers, and project teams practical data that demonstrates the viability of tall wood construction at this scale.
In addition to combustible, heavy timber and noncombustible construction, a new construction type is presently being considered for inclusion into the National Building Code of Canada (NBC). Encapsulated mass timber construction (EMTC) is proposed to be defined as the “type of construction in which a degree of fire safety is attained by the use of encapsulated mass timber elements with an encapsulation rating and minimum dimensions for the structural timber members and other building assemblies.” EMTC is neither ‘combustible construction’ nor ‘heavy timber construction’ nor ‘noncombustible construction’, as defined within the NBC.
EMTC is required to have an encapsulation rating. The encapsulation rating is the time, in minutes, that a material or assembly of materials will delay the ignition and combustion of encapsulated mass timber elements when it is exposed to fire under specified conditions of test and performance criteria, or as otherwise prescribed by the NBC. The encapsulation rating for EMTC is determined through the ULC S146 test method.
In order for structural wood elements to be considered ‘mass timber’, they must meet minimum size requirements, which are different for horizontal (walls, floors, roofs, beams) and vertical (columns, arches) load-bearing elements and dependent on the number of sides that the element is exposed to fire.
EMTC construction in Canada is expected to be limited to a height of twelve-storeys, that is, the uppermost floor level may be a maximum of 42 m (137 ft) above the first floor. An EMTC building must be sprinklered throughout according to NFPA 13 and it is likely that some mass timber will also be able to be exposed in the suites. All EMTC elements are expected to have a minimum two-hour fire resistance rating and the building floor area to be limited to 6,000 m2 for Group C occupancy and 7,200 m2 for Group D occupancy.
There are restrictions on the use of exterior cladding elements in EMTC, as well as other restrictions on the use of; combustible roofing materials, combustible window sashes and frames, combustible components in exterior walls, nailing elements, combustible flooring elements, combustible stairs, combustible interior finishes, combustible elements in partitions, and concealed spaces.
If any encapsulation material is damaged or removed, it will be required to be repaired or replaced so that the encapsulation rating of the materials is maintained.
Additionally, requirements related to construction site fire safety are to be applied to construction access, standpipe installation and protective encapsulation.
EMTC and its related provisions are anticipated to be included in the NBC 2020.
NBC definitions:
Combustible means that a material fails to meet the acceptance criteria of CAN/ULC-S114, “Test for Determination of Non-Combustibility in Building Materials.”
Combustible construction means that type of construction that does not meet the requirements for noncombustible construction.
Heavy timber construction means that type of combustible construction in which a degree of fire safety is attained by placing limitations on the sizes of wood structural members and on thickness and composition of wood floors and roofs and by the avoidance of concealed spaces under floors and roofs.
Noncombustible construction means that type of construction in which a degree of fire safety is attained by the use of noncombustible materials for structural members and other building assemblies.
Noncombustible means that a material meets the acceptance criteria of CAN/ULC-S114, “Test for Determination of Non-Combustibility in Building Materials.”
For further information, refer to the following resources:
Guide to Encapsulated Mass Timber Construction in the Ontario Building Code
ULC S146 Standard Method of Test for the Evaluation of Encapsulation Materials and Assemblies of Materials for the Protection of Mass Timber Structural Members and Assemblies
Fire performance of mass-timber encapsulation methods and the effect of encapsulation on char rate of cross-laminated timber (Hasburgh et al., 2016)
CAN/ULC-S114 Test for Determination of Non-Combustibility in Building Materials
NFPA 13 Standard for the Installation of Sprinkler Systems
This is a Canadian industry wide (average) business-to-business Type III environmental product declaration (EPD) for pre-fabricated wood I-joists. This declaration has been prepared in accordance with ISO 21930 (1), ISO 14025 (2), ISO 14040 (3), ISO 14044 (4), the governing product category rules (5), and ASTM General Program Instructions for Type III EPDs (6). The intent of this document is to transparently disclose comprehensive environmental information related to the potential impacts associated with the cradle-to-gate life cycle stages of wood I-joists manufactured in Canada.
This is a Canadian regionalized industry wide (average) business-to-business Type III environmental product declaration (EPD) for softwood lumber. This declaration has been prepared in accordance with ISO 21930 (1), ISO 14025 (2), ISO 14040 (3), ISO 14044 (4), the governing product category rules (5), and ASTM General Program Instructions for Type III EPDs (6). The intent of this document is to transparently disclose comprehensive environmental information related to the potential impacts associated with the cradle-to-gate life cycle stages of softwood lumber manufactured in various Canadian provinces and regions.
This is a Canadian regionalized industry wide (average) business-to-business Type III environmental product declaration (EPD) for pre-fabricated wood trusses. This declaration has been prepared in accordance with ISO 21930 (1), ISO 14025 (2), ISO 14040 (3), ISO 14044 (4), the governing product category rules (5), and ASTM General Program Instructions for Type III EPDs (6). The intent of this document is to transparently disclose comprehensive environmental information related to the potential impacts associated with the cradle-to-gate life cycle stages of wood trusses manufactured in Canada.
Mark your calendars! WoodWorks Atlantic and the Canadian Wood Council are pleased to present the Wood Solutions Conference in Moncton this fall — and we want you there.
This Guide is designed to help educators increase wood content in their already crowded curricula, exposing students to the unique challenges and opportunities of designing with advanced wood systems, within the context of the program and student performance criteria established, maintained, and evaluated by the Canadian Architectural Certification Board.
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Environment
Safety
Durability
Design Systems
Budget
Construction Management
Fire Resistance
Tall Buildings
Short Buildings 
