This paper focuses on the effects of climate change on Canadian low-slope membrane roofs and provides an overview of CSA A123.26, Performance Requirements for Climate Resilience of Low Slope Membrane Roofing Systems,1 a new standard that can help the roofing industry prepare for and mitigate those effects. Although this article is focused on Canada, a similar approach could be followed for other countries as well, provided they have projected climatic data for locales within their borders. Climate change is not a myth, and it is one of the top priorities for the Canadian government. Environment and Climate Change Canada predicts that Canada will continue to grow warmer under both the lowest and highest greenhouse gas emission scenarios. In Canada, the temperature increase was very gradual until the nineteenth century, followed by a continuing rapid increase (Fig. 1).2 This highlights that under both the best and worst scenarios, the climate is changing, and the intensity and frequency of extreme weather will be constant in the future of Canada. With climate change comes a higher demand on Canadian roofs due to the greater and more frequent impact of weather elements such as extreme wind, intense rain, and high temperatures. A survey by the Institute of Catastrophic Loss Reduction (ICLR)3 identified roofs as the element of the building enclosure most likely to be damaged in severe weather. An example of such roof failures from severe weather is presented in Fig. 2,4 which features photos of a roof failure due to Hurricane Michael in 2018. On that roof, the membrane peeled and the fasteners pulled through the cover board, exposing the system to water infiltration. The ICLR survey3 also emphasized the need to collect and disseminate future climate data and to find solutions to mitigate the effects of climate change on roof systems. Practical climate data and information are needed to be able to adapt roofs to future climate change conditions. Failure to do so can lead to very 8 • IIBEC Interface November/December 2021 Figure 1. Effect of greenhouse gas emissions on the annual temperature change in Canada. Figure courtesy of reference 2. Photo by Geneviève Tremblay on Unsplash costly damages, as illustrated by recent insured losses from extreme weather events (Fig. 3).5 Practical solutions are necessary to aid in the mitigation and preparation of the Canadian construction community to design, build, and maintain climate-resilient roofs. Such solutions did not exist until the National Research Council of Canada (NRCC) undertook the Climate Resilient Buildings and Core Public Infrastructure (CRBCPI)6 project to develop research and development tools to adapt to climate change in Canada. Under the CRBCPI umbrella, the Special Interest Group for Dynamic Evaluation of Roofing Systems (SIGDERS) consulted with members of the North American (NA) roofing community and developed a framework for commercial roof climate resilience with the pledge, “As a key player in the NA roofing community, we are committed to improve the resilience of roof assemblies. We invest in the cost-effective mitigation techniques, durable roofing components and facilitate quality installations to improve the current status of practice.”7 This project led to CSA A123.26,1 which was developed by the CSA Group as a National Standard of Canada. November/December 2021 IIBEC Interface • 9 Figure 2. Roof and rooftop unit failure during Hurricane Michael in 2018. Note: 1 ft = 0.3048 m. Photos courtesy of RICOWI 2018. Figure 3. Examples of insured losses from extreme weather events in Canada. Note: currency shown in Canadian dollars. Figure courtesy of reference 5. CSA A123.26 APPROACH CSA A123.26 is built on the foundation of a holistic approach composed of the following three fundamental criteria: load determination, resistance evaluation, and installation quality control. This approach ensures that the missing link between good codes and durable roofs (quality control during field installation) is fulfilled, leading to a more resilient roof (Fig. 4).8 At an international workshop held at NRC, participants from various sectors of the roofing industry ranked all the elements affecting roofs. From this ranking, installation quality assurance was identified as an overlooked issue that must be addressed because of its significant impact on the roof’s performance.7 Figure 5a shows the normal probability distribution of load, resistance, and installation. For each of these probability curves, the left segment shows the lowest performance. The performance improves as one moves to the right, with the expected mean performance at the peak of the distribution curve. The area under the curve represents the total probability equal to 100%. The factored load and the factored resistance compose the basis of the load resistance factor design (LRFD) procedure. Additional information on the curves can be found in reference 9. The LRFD procedure assumes the load and resistance to be continuous probability distributions. By plotting the load and resistance curves in the same graph, the distribution of the difference between the two values is negative and represents the failure area, shown in grey in Fig. 5b.9 The 𝛽 on the graph in Fig. 5b represents the reliability index, and a larger value will correspond to a higher safety zone for the considered design equation. Although LRFD is mainly used for main force resistance systems, it is gradually being used by the building enclosure community, 10 • IIBEC Interface November/December 2021 Figure 4. Conceptual illustration of the holistic approach that is the foundational concept for CSA A123.26, Performance Requirements for Climate Resilience of Low Slope Membrane Roofing Systems. Figure 5a. Normal probability distribution of load, resistance, and installation. Figure 5b. The load resistance factor design approach for low slope membrane roofing systems (decreased failure zone with the incorporation of installation). Note: 𝛽 = reliability index. Figure courtesy of reference 9. which previously relied on the allowable stress design. Use of LRFD allows for more consistency in the design of buildings. Using the LRFD approach, the factored resistance must be higher than the factored design load. This ensures that the design accounts for variabilities in the load, material properties, and uncertainties in the resistance determination; as a result, the overall reliability of the design is higher. It is assumed that the roof system installed in the field is the same as the system that was tested in the laboratory, and that its resistance is higher than the design requirement. However, the construction process and application techniques can cause variations in the roof system, which can lead to deficiencies and a lower resistance than that obtained in laboratory evaluations. To further increase the reliability of the roof system and decrease the risk of its failure, the obtained LRFD value must consider installation uncertainties (Fig. 5b). A smaller failure zone will lead to greater reliability and a larger “sweet spot.”6 Therefore, to attain resiliency against climate change, the integration and implementation of the three criteria must be cohesively met. CSA A123.26 DEVELOPMENT PROCESS The task group charged with developing CSA A123.26 operated under the norms of the CSA Group, with the participation of stakeholders from across North America (see Table 1 for the list of members). There were two working groups within the task group focused on the wind and rain sections. The RCI Foundation Canada contributed toward the development of experimental data to validate the field wind uplift protocol, and several IIBEC members participated in the consensus process by contributing to content development for the standard. To gather input from peers, Gaur and coauthors presented the standard’s framework to the roofing industry.10 The extensive collaboration with diverse stakeholders was critical for identifying the best practices followed by the industry and ensuring the completion of the consensus-based standard. This collaboration also helped identify strategic and practical solutions for implementation of the standard by the construction community. The sidebar to this article, “CSA A123.26 Features and Benefits,” highlights those solutions from the perspective of users of CSA A123.26. CSA A123.26 FRAMEWORK The requirements in CSA A123.26 are built on top of minimum requirements in the National Building Code of Canada11 (NBCC); in other words, CSA A123.26 specifications are more stringent than the NBCC requirements. Note that CSA A123.26 currently provides requirements for wind and rain only. However, the task group is working on expanding the standard to incorporate holistic measures for temperature as well. In this consensus-based standard, the performance requirements for climate resiliency of low-slope membrane roofs vary by location in Canada. Figure 6 uses two weather events (wind and rain) to illustrate the structure of the standard. November/December 2021 IIBEC Interface • 11 Figure 6. The layout of standard CSA A123.26, Performance Requirements for Climate Resilience of Low Slope Membrane Roofing Systems. Note: numerals in ovals signify the number of requirements for Gold in each category. Organization Contributor Fishburn Building Sciences Group Inc. D. C. Fishburn* WSP Canada Inc. J. G. Levaque* Johns Manville M. Allaire* National Research Council of Canada B. Baskaran* EXP Inc. B. Bernard* Firestone Building Products Y. Bhowany Tremco Roofing & Building Maintenance K. Boyce* IKO Industries Ltd. G. Christopher Soprema Inc. J. F. Côté* Ontario Ministry of Municipal Affairs and Housing M. El Semelawy GAF H. Estes Canadian Roofing Contractors Association T. Ferreira* EPDM Roofing Association T. Hutchinson* Roofing Contractors Association of British Columbia J. Klassen Georgia Pacific M. Kuronen* Carlisle SynTec J. Malpezzi National Roofing Contractors Association M. Rupar* Institute for Catastrophic Loss Reduction D. Sandink Henry Company P. Saunders* National Research Council of Canada F. Shyti* Duro-Last Roofing R. VanWert* SIKA Sarnafil P. Yurich *IIBEC member. Table 1. CSA A123.26 task group membership. 12 • IIBEC Interface November/December 2021 CSA A123.26 Features and Benefits— An IIBEC Member’s Perspective By Doug Fishburn, GRP Fishburn Building Sciences Group Inc. Hornby, Ontario, Canada FEATURES AND BENEFITS FOR BUILDING OWNERS • Provide clear direction to the building designer of the owner’s expectation for the roof performance. • Provide assurance that the roofs have been designed to meet or exceed the national building code requirements. • Provide a level of known performance to the purchaser if the property ownership changes. • Reduce the possibility of perspective purchaser to reduce the sale price if the design and installation of the roof is otherwise unknown. • Will reduce the life cycle cost of the roof since the likelihood of a failure is reduced. • Increase the roof reliability to function during major weather events. • Provide a known design standard to which to compare the roof performance should a weather event result in wind damage, ponding overstress, or roof leaks. • Reduce ambiguity, which should result in more accurate bids to the owner. FEATURES AND BENEFITS FOR BUILDING DESIGNER • Provide clear direction from the building owner to the design as to the owner’s expectation for the roof performance in order to lower the risk of contractor’s value engineering the roof after the bids are received. • Establish a known standard for design and quality assurance from the outset. • Provide a simplified approach to prepare specifications and drawings. • Provide a guide to follow when preparing specifications and drawings. • Provide a guide when reviewing shop drawings. • Reduce the risk of failure that could otherwise involve the designer in a construction claim. FEATURES AND BENEFITS FOR CONTRACTOR • Provide clear direction on how the roof is to be constructed. • Eliminate ambiguity, and assist the contractor in providing accurate bids. • Provide a known standard that can be relied upon for warranty purposes. • Provide a level of quality assurance which is intended to reduce oversights in the contractor’s work. • Reduce the risk of callbacks and warranty claims. WHY IS THE STANDARD NEEDED? • Currently, the national building code is the only authoritative standard used in Canada. Typically, the building code does not apply to reroofing. CSA A123.26 could apply to both new construction and reroofing. • CSA A123.26 is a consensus standard that incorporates the current knowledge of roofing trade organizations— design community as well as roofing manufacturers. There is no consensus standard for reroofing of low-sloped roofs in Canada. This standard fills the void. • The current recommendations of trade associations and manufacturers provide guidance on current practices, but they do not address issues that can result in an increase in wind or rain events that are anticipated to occur from global warming. Most manufacturers’ warranties have limitations if the wind speeds exceed a specific requirement. Manufacturers could simply state that the roof must be designed and constructed in conformity to CSA A123.26. If they adopt this approach, it would reduce the warranty claims. • This standard allows roofs to be designed and constructed with more predictability—particularly when the roof is exposed to extreme weather events. Based on my experience, most roofs are found unserviced due to construction oversights. This standard is intended to address this problem. HOW THE STANDARD COULD APPLY • The standard could be referenced by owners, designers, manufacturers, roofing trade organizations, or contractors as to the quality of roofing intended to be achieved. The user guide, when developed, could be used as a reference guide by the entire roofing community as to how to design and construct a roof that has proven performance or benefits over current standards. • The standard is adaptable for most roof membrane systems currently used in Canada and is applicable for both small and large projects, whether they apply to new or reroofing projects. WHAT IS THE ADVANTAGE OF APPLYING THE STANDARD? • Roofs designed to this standard are more reliable and should last longer, with fewer maintenance problems and roof leaks. Wind Requirements The wind requirements in CSA A123.26 are grouped into specific requirements for the roof itself and for the rooftop add-ons. These requirements aim to increase the resiliency of both the roof and the areas where rooftop addons are installed. The latter are a major issue during severe wind events.12 Rain Requirements The rain requirements in CSA A123.26 are divided into categories for rainwater resistance and rainwater control. The rainwater resistance requirements ensure that water infiltration does not occur. The rainwater control requirements address how to account for climate change while meeting the NBCC expectation that roofs must be designed to allow the efficient removal of water. [CSA A123.26 IMPLEMENTATION For easy implementation of CSA A123.26, the NRCC launched the “Climate Roof Calculator on the Internet” (Climate-RCI) tool.13 This publicly available web application determines the climate severity for all Canadian locations listed in the 2015 NBCC based on current and projected climate data. It also determines the performance level (Bronze, Silver, or Gold) for commercial roofs’ climatic resilience requirements in accordance with the CSA A123.26 standard. The performance level is the combination of a climate severity classification (Normal, Severe, or Extreme) and a ranking from the Resilience Index (1, 2, or 3; with 3 being the most resilient). If the performance level is determined to be “Silver” by the Climate-RCI, the user should follow the Silver requirements in CSA A123.26. The standard outlines 12 Silver requirements that must be fulfilled for wind and 14 for rain. If a Gold performance level is assigned by the Climate-RCI, the Silver requirements must be fulfilled first, and then an additional six requirements for the wind and rain must be met. Figure 7 presents a case study to illustrate the use of the Climate-RCI. The CSA A123.26 annexes provide additional information for the user, and NRCC is November/December 2021 IIBEC Interface • 13 Figure 7. A case study with step-by-step screenshots from the Climate-RCI tool. Figure 7 continued on next page. CSA A123.26 Features and Benefits— Perspectives from Two RCI Foundation Canada Members “CSA A123.26 will benefit the roofing community by helping mitigate roofing failures in the future,” according to Marc Allaire of the RCI Foundation Canada. Some of the most important features and benefits of CSA A123.26 are that “the standard helps define the need for upgrades for both wind and rain and offers practical solutions to better roofing installations in both key areas.” It also helps adapt depending on location, severity, and need. “The insurance companies absolutely want to adopt this standard to minimize loss. But it is not only money, it is also inconvenience and personal loss when a project gets flooded or encounters a high-wind event. Designers, architects, engineers, owners, contractors, [and] manufacturers should be aware that there is an improved design that can be used if they so choose. Insurance premiums could be reduced when the standard is used much in the same way that FM operates.” When asked how he would apply the standard, Allaire replied, “I still feel that the code should provide a section for improved design. Not mandate it but have it in the code so that if someone wants to upgrade their design, they have guidance to do it. I think of data centers, warehouses with high-end goods. Better, long-performing roof assemblies is one of the advantages of the standard. I truly feel that as the climate changes, we need to adapt to the changes so that we can go back to 30- and 40-year roofs that have performed in the past but are not so common now. I know that some buildings are built on a 20-year life cycle, but schools, medical centers, hospitals, universities, colleges, and so on are built to endure, and this standard provides an opportunity for that.” Robert Elsdon, F-IIBEC, believes that “the benefits of the research and testing done will become more evident as time goes on with the present rate of global warming and the wind and rain effects that result from this.” He also expressed his disappointment “that the hard work put in by many was not able to be part of the NBCC. However, I understand the reasoning behind the decision. Regardless of this decision, the information presented by the combined efforts of all involved is valuable for building owners, designers, [and] installers, as well as insurance companies, to name a few.” Screenshot Remarks Introduction page of Climate-RCI. preparing a user’s guide to further assist in the implementation of this standard. This guide will provide detailed drawings, such as the one shown in Fig. 8, as well as field photographs displaying the implemented requirements. Figure 8 provides a visual of the Silver requirement used in the Fig. 7 case study. The dimensions required by the standard are noted, along with the appropriate elements and their placement. Alongside the detailed drawing, the user guide will feature a field photograph of how this requirement is fulfilled. CONCLUSION The NBCC provides users with the minimum requirements that must be fulfilled. As noted previously, the consensus-based, voluntary standard CSA A123.26 goes beyond the minimum requirements required by NBCC. Because it is more stringent than the code, CSA A123.26 cannot be incorporated into NBCC. However, CSA A123.26 is currently being reviewed for inclusion in the Canadian National Master Specification, a comprehensive master specification used as a framework for writing construction specifications for projects.14 CSA A123.26 delivers responsive and time- 14 • IIBEC Interface November/December 2021 Figure 7 continued. A case study with step-by-step screenshots from the Climate-RCI tool. Screenshot Remarks Selecting the city of Whistler in British Columbia as an example yields the climate severity results shown. If a resilience index of 2 is selected, the roof performance requirement will be Gold for wind. ly guidance for the Canadian construction community to prepare for and mitigate effects of climate change. The first standard of its kind in the world, CSA A123.26 helps remove barriers to innovation for Canadian small and mid-size enterprises in the construction world. The standard’s holistic approach with implementable specifications generates measurable outcomes for stakeholders (Infrastructure Canada, the building enclosure industry, and construction clients). Furthermore, the standard provides quality assurance metrics, and it allows Canadians to categorize their buildings as Bronze, Silver, and Gold. This performance labeling signifies that a building has been designed to be more resilient. Buildings with leak-free, resilient roofs provide improved quality of life for Canadians and increased efficiency and productivity for the roof and the building. REFERENCES 1. CSA Group. 2021. Performance Requirements for Climate Resilience of Low Slope Membrane Roofing Systems. CSA A123.26-2021 EDITION UPDATE 1. Mississauga, ON: CSA Group. 2. Bush, E.; and D. S. Lemmen. 2019. Canada’s Changing Climate Report. Ottawa, ON: Government of Canada. changingclimate.ca/CCCR2019. 3. Sandink, D. 2020. CCCS Buildings Module—Survey Results/Overview. Institute for Catastrophic Loss Reduction. climatedata.ca/buildings- module-context 4. Roofing Industry Committee on Weather Issues. 2019. “Wind Investigation Report: Hurricane Michael, October 25-26, 2018.” ricowi. com/reports. 5. Natural Resources Canada (NRCAN). 2018. Personal communication <via email>. 6. Government of Canada. 2020. “Climate-Resilient Buildings and Core Public Infrastructure Initiative.” infrastructure.gc.ca/plan/crbcpi-irccipb- eng.html. 7. Baskaran, A., S. Molleti, D. Lefebvre, and D. Van Reenen. 2017. “Climate Change Adaptation Technologies for Roofing and Insulation.” Proceedings of the North American Consultation on Climate Adaptation Technologies. Ottawa, ON: National Research Council of Canada (NRCC). 8. Baskaran, B.; D. Lefebvre, M. Chavez; and S. Molleti. 2019. “Good Codes vs. Durable Roofs—Which Is the November/December 2021 IIBEC Interface • 15 Figure 7 continued. A case study with step-by-step screenshots from the Climate-RCI tool. Screenshot Remarks If a resilience index of 2 is selected, the roof performance requirement will be Silver for rain. One of the requirements that must be fulfilled for the Gold performance level. According to CSA A123.26, if the performance level was established as Silver, the independent inspector would have to be engaged for only 25% of the days of work. One of the rain requirements that has to be fulfilled for the Silver performance level. This requirement provides the necessary distances a drainage pipe shall be above grade and with respect to the building. It also requires the usage of a splash pad at the output. Missing Link? Where Is the Sweet Spot? Proceedings: RCI International Convention and Trade Show. iibec. org/wp-content/uploads/2019-baskaran- lefebvre-chavez-molleti.pdf. 9. Baskaran, B.; D. Lefebvre, S. Molleti; and N. Holfcroft. 2018. “Climate Change Adaptation Technologies for Roofing.” Proceedings: 33rd RCI International Convention and Trade Show. iibec.org/ wp-content/uploads/2018-cts-baskaran- lefebvre.pdf. 10. Gaur, A.; F. Shyti; and B. Baskaran. 2020. “A Framework for Climate- Resilient Performance Standard of Commercial Roofs.” Construction Canada. constructioncanada.net/aframework- for-climate-resilient-performance- standard-of-commercialroofs. 11. Canadian Commission on Building and Fire Codes. 2015. National Building Code of Canada. Ottawa, ON: NRCC. doi: 10.4224/40002005. 12. Baskaran, B.; D. Roodvoets; and H. Yew. 2019. “Which Is the Weakest Link—How Can It Be Stronger? Lessons Learned from the 20 Years of Hurricane Investigations.” Presented at the IIBEC International Convention (virtual meeting), June 2020. 13. NRCC. 2021. “Climate-RCI.” nrc.canada. ca/en/research-development/products- services/software-applications/ climate-rci. 14. NRCC. 2021. “Canadian National Master Construction Specification.” nrc.canada.ca/en/certifications-evaluations- standards/canadian-national-master- construction-specification. ACKNOWLEDGMENTS Thank you to the Special Interest Group for Dynamic Evaluation of Roofing Systems (SIGDERS), which contributed to the development of the CSA A123.26 standard. SIGDERS was formed from a group of partners interested in roofing design. These partners included Altenloh, Brinck & Co. US Inc., Atlas Roofing Corporation, Canadian Roofing Contractors’ Association, Carlisle SynTec Systems, DuPont Performance Building Solutions, Duro-Last Inc., EXP Inc., Firestone Building Products, IIBEC, IKO Industries Ltd., Johns Manville Inc., OMG Roofing Products, Roofing Contractors Association of British Columbia, Rockwool, Sika Sarnafil, Soprema Canada Inc., and Tremco Inc. Thank you as well to members of the RCI Foundation Canada Board of Directors— Albert J. Duwyn, Ralph Paroli, Robert J. Elsdon, and Marc Allaire—and the CSA A123.26 task group co-chairs, Doug Fishburn and Jean-Guy Levaque. Please address reader comments to chamaker@ iibec.org, including “Letter to Editor” in the subject line, or IIBEC, IIBEC Interface, 434 Fayetteville St., Suite 2400, Raleigh, NC 27601. Flonja Shyti is a research council officer with the Construction Research Centre of the National Research Council of Canada. As part of the roofing and insulation group, her research focuses on the performance requirements for climate resilience of commercial and residential roofs and their integration into codes. She is a member of the Single Ply Roofing Industry and IIBEC and is registered with Professional Engineers Ontario. She received her master’s degree in civil engineering from the University of Ottawa. Shyti can be reached at Flonja.Shyti@ nrc-cnrc.gc.ca. Flonja Shyti, MASc Bas A. Baskaran, PhD, PEng, is a group leader at the National Research Council of Canada, where he researches the performance of roofing systems and insulation. He is an adjunct professor at the University of Ottawa and a member of the Roofing Committee on Weather Issues (RICOWI), IIBEC, Single Ply Roofing Industry (SPRI), and several other technical committees. Baskaran is a research advisor to various task groups of the National Building Code of Canada. He was recognized by Queen Elizabeth II with a Diamond Jubilee medal for his contribution to fellow Canadians. Baskaran can be reached at bas.baskaran@nrc-cnrc.gc.ca. Bas A. Baskaran, PhD, P. Eng. 16 • IIBEC Interface November/December 2021 Figure 8. Example of rain requirements to be explained in the user guide for CSA A123.26, Performance Requirements for Climate Resilience of Low Slope Membrane Roofing Systems.
