Pushing the Envelope Canada

< PreviousPushing the Envelope Canada 11 n n n UP FRONT Message from the President OBEC President Mila Aleksic B.Arch.Sc., M.A.Sc. Professor, Centre for Construction Engineering Technologies George Brown College BOARD OF DIRECTORS President: Mila Aleksic, B.Arch.Sc., M.A.Sc., George Brown College Vice-President: Daniel Aleksov, P.Eng., BSS, Leading Edge Building Engineers Inc. Treasurer: Negar Pakzadian, B.Eng., M.Arch., M.B.Sc., BSS, CPHD, City of Pickering Directors: Brian Abbey, A.A.T.O., BSS, A.Sc.T., CSC, BCQ, ADTEK Building Consultants Matthew Gelowitz, M.A.Sc., CPHC, LEED® AP, Synergy Partners Consulting Ltd. Paul Johannesson, Dipl.Arch.Tech., CET, Siplast Jelena Madzarevic, M.B.Sc., EllisDon Corporation Andrea Mucciarone, B.A., M.B.Sc., BSS, Read Jones Christoffersen Ltd. Rob Quattrociocchi, BSS, Synergy Partners Consulting Ltd. Jimmy Tang, M.B.Sc., B.Arch.Sc., Infrastructure Ontario A s we start a new year, it is important that we take stock of what we ac- complished in 2022 and reﬂect on how we can make 2023 even more fulﬁlling, productive and fun. The Ontario Building Envelope Council (OBEC) saw a remarkably busy 2022 with many amazing events held throughout the year. We were immensely proud to host the Canadian Conference on Building Science and Technology (CCBST) from October 27- 28, 2022. The conference was jam packed with thought-provoking speakers who tackled a variety of topics covering Healthy, Efﬁcient and Resilient buildings. We wel- comed over 300 attendees from all over the country who had a lot of fun mingling, at- tending concurrent sessions and networking on the trade show ﬂoor amongst some sensa- tional exhibitor booths. I want to again thank the speakers, the attendees and our sponsors and exhibitors for supporting this event! The next CCBST will be hosted in beautiful Jas- per, Alberta in 2025 – make sure you don’t miss it! This year, the board has decided to focus on making our events as exciting and ac- cessible as possible. To this end, we will be alternating between in person and webi- nar events to allow our members to enjoy the beneﬁts of in-person interaction and the ﬂexibility webinars offer. We hope this approach will help us reach the widest pos- sible audience while increasing engagement with our members. We have also decided to begin alternating the location of our dinner meetings with the hope of making them more accessible to our members who could not make it to previous dinners because of travel difﬁculties. Building Science education has always been a core value at OBEC. We strive to en- courage and empower the next generation of building science professionals and take every opportunity to instill a passion for our profes- sion with students across Ontario. As we ex- pand our OBEC student chapters, of which we now have four (University of Toronto, Toronto Metropolitan University, George Brown College, and University of Waterloo), we are going to be inviting student members from these chapters and their faculty advisors to attend our in-person events (one chapter per event) to showcase our chapters and en- gage with these students. OBEC’s footprint is also starting to grow within industry. We will look to ex- pand our partnerships in 2023 and will again have a booth at the CSC Expo this year. We will also be collaborating with BECOR on joint webinars, the ﬁrst of which we will host in April. We will con- tinue to look for additional organizations that we can partner with and bring forward even more exciting events to our members in 2023 and beyond. As we did in the past, OBEC will be honouring our rising stars with the OBEC Rising Star Award. This award is given out biennially to recognize individuals that dem- onstrate exceptional knowledge of the de- sign, construction, and performance of the building envelope. Nominations are now open, so if you know somebody who is new to the building science industry (with a min- imum of ﬁve years of experience) who has consistently promoted better functioning of the building envelope and has or will con- tinue to make a substantial contribution to the building science ﬁeld within the context of building enclosures – nominate them for the OBEC Rising Star Award! The dead- line to submit the application is September 1, 2023. At the Annual General Meeting last Oc- tober, the names of the OBEC Board mem- bers for 2023 were announced. I want to wel- come Brian Abbey back to the board – great to have you back Brian! I would also like to thank Erica Barnes for her service on the OBEC board and her immense contribution. I also want to take the opportunity to express my gratitude to all our board members and committee members, who kindly volunteer their time and energy to further OBEC’s mission. We always welcome additional help and would love to see more of our members get involved in any capacity they can. Please e-mail us at info@obec.on.ca if you are inter- ested in volunteering.nPushing the Envelope Canada 13 E xtreme weather events are becoming more frequent, intense, and longer due to climate change. These ex- treme events lead to weather shocks, which can adversely affect the expected perform- ance of the exposed building envelope com- ponents and systems. In Canada, design loads for building en- velope are calculated in accordance with the National Building Code of Canada, utilizing the climatic loads determined using Appen- dix C.1 The data enlisted within is based on historical observations that do not account for future climatic conditions for Canadian cities, or for the effect of weather shocks on the components and systems. The Na- tional Research Council of Canada (NRC) developed a protocol outlined in the CSA A123.26 “Performance requirements for cli- mate resilience of low slope membrane roof- ing systems”2 to account for future extreme climactic loads in the design and construc- tion of roofs.3 These future climatic loads for main weather parameters such as wind, rain, and temperature can be found on “Climate-RCI” for a range of global warming magnitudes from 0.5˚C to 3.5˚C. Climate-RCI is a web based tool and can be accessed via NRC’s wind roof calculator.4 NRC is now address- ing the effect f weather shocks as part of the recent "Climate Resilient for Built Environ- ment" initiative. Weather shocks are several occurrences of rapid and signiﬁcant temper- ature variations, such as a hot summer day followed by sudden rain and a drop in temper- ature, or a cold winter day followed by a sud- den increase in temperature (See Figure 1, below). These shocks can cause deterioration of the exposed rooﬁng and other build- ing envelope materials. Their continued occurrence in an increased and acceler- ated manner leads to property reduction and rapid deterioration of components and systems. Establishing weather shock parameters is extremely important because it allows us to mimic the experimental test protocols and examine their impact on the exposed part of components and any sub-se- quential effect on the systems. The effect of weather shock and the thermal stresses will be different for various materials part of the rooﬁng systems. The components that are exposed to the weath- er elements will behave differently than the other components inside the roof assembly. The thermal expansion and contraction at different rates and the subsequent stresses placed on the materials can lead to breakage and cracks due to the tension formed in the material. Under such conditions, the roof membrane can be popped at the seams, or the n n n FEATURE By Flonja Shyti MASc., Abhishek Gaur Ph.D., Bas Baskaran Ph.D., P.Eng., Construction Research Centre of the National Research Council of Canada A Weather Shocks Protocol to Investigate Building Envelope Components for Changing Climate Figure 1. Typical hot and cold weather shock. Graphics courtesy of Flonja Shyti.14 Spring 2023 • Ontario Building Envelope Council attachment fasteners can protrude. Damages are more prone near roof penetrations where materials with very different compositions can be found. While the issue of stresses created within the rooﬁng components due to the change in temperature is one that has been previously studied, with climate change, temperature, and consequently their ﬂuctuations, are expected to be greater and more frequent. Therefore, developing a framework of how to determine the weather shock parameters and incorporate them into testing method- ologies is critical in establishing durability characteristics. FRAMEWORK DEVELOPMENT Quantifying weather shocks that will occur in the future for practical application was discussed with the industry. Based on the discussions a framework was developed using future climatic loads and how to incor- porate them into the experimental method- ology. Initially, hourly temperature time ser- ies available for 564 locations across Canada were analyzed for hourly ﬂuctuations. The data available for these locations spanned 10 to 20 years with most of the locations having 15 years of data available. A thresh- old value of 5˚C was chosen to identify the instances of hourly ﬂuctuations above the threshold. The number of these cycles per year ob- tained from the time series were ﬁt to a Pois- son distribution (probability of exceedance is two per cent) and the number of cycles for 50-year return periods were determined. For the analyses, the period from May to August was considered summer, during which a hot weather shock would occur, and December FEATURE n n n Figure 2. Weather shock framework summary. Figure 3. Climatic zone map of Canada and weather shock data. Graphic sourced from the National Research Council of Canada. to March was winter, during which a cold weather shock would occur. The above is summarized in Figure 2, below. The hot and cold weather shock values are initially obtained based on air temper- ature. The surface temperature that a roof component will reﬂect under a speciﬁc air temperature will differ based on the com- ponent and its position within the system. That’s why establishing the relationship be- tween the component temperature and air temperature is required. Thereafter, the hot and cold weather shock the component will be experiencing in a scenario of 2˚C global warming magni- tude is determined. This framework can be followed for all building envelope compon- ents and is not limited to roof components. As well, the parameters can be established for other global warming magnitude ranges from 0.5˚C to 3.5˚C. INCORPORATION OF WEATHER SHOCKS INTO EXPERIMENTAL METHODOLOGY The summary of the weather shock re- sults for all the provinces and territories in Canada is shown in Table 1 on page 15. For the framework, the concentration was on the maximum temperature for the hot weather shock to establish the worst-case scenario. Similarly, for the cold weather shock, the minimum temperature was considered. For a 50-year return period, the number of cyclic events determined to occur for the hot and cold weather shock is also shown in Table 1. Alternatively, the weather shock data can also be visualized using the existing climate zone map of Canada as shown in Figure 3 below. Zones 7A and 7B are combined for simplicity and have the highest number of weather shock occurrences for both the hot and cold weather shocks. Zone 7 also has Pushing the Envelope Canada 15 one of the highest maximum temperatures and lowest minimum temperatures com- pared to other zones. APPLICATION OF WEATHER SHOCK PARAMETERS For the asphalt shingle the relationship of the component temperature was deter- mined to be twice that of the air temper- ature.5,6 Using this information and follow- ing the framework, in Figure 2 the cold and hot weather shock component temperatures and their respective number of occurrences are determined. Since the materials are cur- rently evaluated at lab temperature, that temperature was maintained as the base- line of the weather shock cycling. Also, to replicate the cycling that already naturally occurs with the change in seasons the hot and cold weather shocks were alternated. An important step for incorporating the weather shock framework into testing is the duration of the hot and cold cycles to ensure practicality of the experiments. An example of how this can be achieved is by setting a practical duration of the entire weather shock cycle and adjusting the duration of each cycle. This must be achieved while ensuring that the total number of ﬂuctuations for hot and cold weather shocks is maintained. An example of a dark-coloured roof covering (asphalt shin- gle) is shown in Figure 4 above.. The hot and cold weather shock cycle has a total duration of 15 days. Within each day there are eight hot REFERENCES: 1.Canadian Commission on Building and Fire Codes, National Building Code of Canada, Ottawa: National Research Council Of Canada, 2015. 2.CSA Group, CSA A123.26-21 Per- formance requirements for climate resiliencce of low slop membrane rooﬁng systems, Ottawa. 3.B. Baskaran and F. Shyti. “A new climate resilient tool for the commer- cial rooﬁng community.” Interface, pp. 8-16, 2021. 4.Government of Canada. “Wind-Roof Calculators on the Internet (Wind- RCI).” https://nrc.canada.ca/en/re- search-development/products-services/ software-applications/wind-roof-calcu- lators-internet-wind-rci. 5.P. Berdahl, H. Akbari, R. Levinson and W. A. Miller. “Weathering of Rooﬁng Materials – An Overview.” Journal of Construction and Building Materials, vol. 11, no. 4, pp. 423-433, 2008. 6.I. M. Giammanco, T. M. Brown and H. E. Sommers. “IBHS Roof Aging Farms – 2014 Measurement Summary.” Insurance Institute for Business and Home Safety, 2015. Province Hot Weather Shock Cold Weather Shock # of Occurrences Max Temp # of Occurrences Min Temp NB533861-32 NL393745-35 NS373825-22 PE223423-21 ON713963-36 QC614274-42 MB654251-39 SK724463-39 AB1164152-37 BC704292-34 NT603880-41 NU243352-43 YT553584-41 Table 1. Maximum and minimum temperatures and the number of events across Canada for hot and cold weather shocks. n n n FEATURE and six cold weather shock cycles. The dur- ation of 15 days, along with the breakdown of eight hot and six cold cycles a day and the dur- ation of each cold and hot cycle can all change to better reﬂect the building envelope materi- al being evaluated. An asphalt shingle will not absorb and retain heat in a similar manner to a beige wall siding. Therefore, the factors that must be re- spected when determining the composition of the cycles are: •The cold and hot component weather shock temperatures. •The number of weather shock occur- rences. The evaluation of building envelope components and systems based on the de- veloped weather shock conditioning is critic- al and will help us better understand the dur- ability of building components and systems. This can provide better in-service perform- ance predictions. n Flonja Shyti, MASc., is a Research Coun- cil Ofﬁcer and Dr. Abhishek Gaur is an As- sociate Research Ofﬁcer for the Construction Research Centre of the National Research Council of Canada. Dr. Bas BaskaranP.Eng., is a Group Leader at the National Research Council of Canada. Figure 4. Example of the application of the hot and cold weather shock for a dark-coloured roof covering.Pushing the Envelope Canada 17 O n December 14, 2021, a six-storey multi-unit residential building under construction in the Greater Toronto Area reported roof damage caused by a strong wind event. The fully adhered thermoplastic polyoleﬁn (TPO) roof assem- bly over concrete deck with a layer of vapor retarder, two layers of polyisocyanurate in- sulation and a layer of high density polyiso- cyanurate coverboard had experienced wind uplift damages due to high wind conditions that reached up to 96.3 km/h, as recorded by the nearby weather stations. The damage covered approximately 15 per cent of the roof assembly, across four different locations. While the TPO membrane stayed in place adhered to the coverboard layer, the cover- board had separated from the insulation layers as they had shifted and stacked one over another. In several instances, the top insulation layer had experienced facer co- hesion failure. The roof assembly appeared to have been held from complete roof area blow off by the fully adhered TPO mem- brane ﬂashing ply and perimeter reinforce- ment securement strip. Following the occur- rence of the roof damage, large rolls of roof membrane and containers of adhesive were placed throughout the roof area by the con- tractor in an attempt to temporarily restrain portions of failed roof assembly and prevent further damage. At ﬁrst glance, the roof assembly failure appeared to be due to heavy wind conditions experienced at the time of the event that may have exceeded wind uplift design parameters. However, subsequent review determined that the wind conditions were found to fall within the expected wind load range for the site. Additionally, various incomplete and unsealed scupper openings in the perimeter parapet were originally suspected to have contributed to the roof failure. The project experienced a series of missteps leading to the failure event, all potentially contributing to create a ‘perfect storm’ scenario. These potential contributing factors include: failure by the designer to specify site-speciﬁc wind uplift values in the design speciﬁcation; alternative questionable meth- ods of compliance employed by the manu- facturer; and poor material handling, poor workmanship and poor quality control by the contractors during construction. While the Wind Uplift Failure of a Roof Assembly: The ‘Perfect Storm’ By Sathya Ramachandran, Mark Summerfield, and Anthony F. Perri, EXP Services Inc. Wind uplift damage of the roof assembly. Photos courtesy of Sathya Ramachandran. n n n FEATURE18 Spring 2023 • Ontario Building Envelope Council primary cause of failure can be attributed to one or more of the above missteps, this roof failure incident provided some insights that are valuable lessons learned. As is a com- mon issue in the rooﬁng industry, installation of the roof assembly proceeded despite the above missteps that were ﬂagged and dis- cussed by project team members, prior to the wind failure incident. DESIGNER’S RESPONSIBILITY As referenced in the Advisory Bulletin issued in June 2018 by the Canadian Rooﬁng Contractors Association (CRCA) titled, Roof- ing Contractors and Designers Responsibility, there is an expectation from the industry part- ners, as a designer’s responsibility, to conﬁrm and specify the site-speciﬁc wind uplift resist- ance values in the process of meeting code requirements. The reasoning for this design responsibility has been dissected at length in an article, Understanding the British Columbia Building Code – Roof Design: From Code to Speciﬁcation, Part 3 of an article series in the Fall 2021 edition of Rooﬁng BC Magazine. As noted in the Advisory Bulletin by CRCA, the practice is currently a hit or miss. While it is not the scope of this article to delve into the validity of this expected de- sign responsibility in relation to the Ontario Building Code (OBC), which does not ap- pear to have been reciprocated by the design community, it is prudent for the designers to be cognizant of the code requirements and either include or engage qualiﬁed profession- als to conﬁrm and/or verify the site-speciﬁc wind values to eliminate ambiguity, uphold standard of care, reduce risk and liability, and prevent cutting corners. The Nation- al Building Code of Canada (NBCC) has a requirement for the roof assemblies to resist the project speciﬁc wind uplift resistance val- ues calculated based on load resistance fac- tor design (LRFD) with inputs including the geographical location, terrain of the project site, openings in the building, height of the building, size of the roof area and height of the parapet. To ease the burden on the designer from calculating the wind uplift resistance values using the formula listed in the code, the Na- tional Research Council of Canada (NRCC) has developed and published an online tool, Wind-RCI, that can calculate these values based upon the user’s site-speciﬁc input. This tool can be used to calculate the required size or width and corresponding wind uplift resistance values for ﬁeld, perimeter, and corner zones of each roof area as required, based upon the building information and site location characteristics. It is important to note that, as is the case with any tool, it is the user’s responsibility to verify the values generated. At the subject project, the speciﬁcations included a reference to CSA A123.21, Stan- dard Test Method For The Dynamic Wind Uplift Resistance of Membrane-Rooﬁng Systems, but failed to include any reference to the site speciﬁc wind uplift resistance values and the requirement for the roof assembly to resist them. As the title indi- cates, the above referenced standard de- lineates the test method to verify the per- formance of a roof assembly, but not the design requirements. The site-speciﬁc wind uplift values were subsequently veriﬁed as follows: •Mechanical Penthouse: -2.39 kPa (-50 psf) @ Field; -3.35 kPa (-70 psf) @ Per- imeter; and -4.3 kPa (-90 psf) @ Corners •4 Storey Main Roof: -1.67 kPa (-35 psf) @ Field; -2.15 kPa (-45 psf) @ Perimeter; and -4.26 kPa (-89 psf) Corners •6 Storey Main Roof: -1.72 kPa (-36 psf) @ Field; -2.25 kPa (-47 psf) @ Perimeter; and -4.4 kPa (-92 psf) @ Corners •Entrance Canopy Roof: -1.96 kPa (-41 psf) @ Field; -2.77 kPa (-58 psf) @ Per- imeter; and -4.06 (-85 psf) @ Corners MANUFACTURER’S RESPONSIBILITY The manufacturer has the responsibility to provide a tested roof assembly that is test- ed to resist the site-speciﬁc wind uplift values at all zones. Currently, major manufacturer’s maintain a portfolio of rated systems that are designed, tested and rated, which in discus- sion with the rooﬁng trade can be selected and proposed for the project. For the subject building, the rooﬁng contractor proposed a roof assembly as a substitution to the pre- scribed rooﬁng systems in the speciﬁcations as follows: •60 mil single-ply TPO membrane fully adhered; •High density inorganic coated ﬁberglass facer polyisocyanurate insulation adhered with ¾ inch thick beads of foam adhesive spaced at 12.0 inches on centre.; •Fiberglass reinforced organic facer poly- isocyanurate insulation adhered with ¾ inch thick beads of foam adhesive spaced at 12.0 inches on centre; •Fiberglass reinforced organic facer poly- isocyanurate insulation adhered with ¾ inch thick beads of foam adhesive spaced at 12.0 inches on centre; •Self-adhered elastomeric sheet vapour barrier membrane with polyethylene facer in primer; and •Structural concrete deck. The assembly proposed was a tested sys- tem in accordance with CSA A123.21 by a Cut test of the roof assembly at the failed locations showing inadequate installation. FEATURE n n nPushing the Envelope Canada 19 third-party testing lab in the United States, which had experienced an insulation facer cohesion failure at -5.03 kPa (-105 psf). The system can be rated for a wind uplift resist- ance of -3.35 kPa (-70 psf). While this rating was adequate to meet the site-speciﬁc wind uplift resistance requirements at the ﬁeld and perimeters of all four roof areas, the rat- ing was inadequate at the corners of all roof areas. Despite the Manufacturer’s claim that prescriptive enhancements based on the ANSI/SPRI WD-1 - WindDesign Standard Practice for Rooﬁng Assemblies’ extrapolation method, of applying additional adhesive (by reducing the spacing of the adhesive ribbon pattern from 12 inches on centre at all zones to 12 inches on center at the ﬁeld zones, 8 inches on centre at the perimeter zones and 6 inches on centre at the corner zones), would meet the site-speciﬁc wind uplift resistance requirements at the corners, the system’s rating was questionable without knowing the mode of failure. Given the understood mode of failure being the insulation facer cohesion, apply- ing additional adhesive in the system may or may not have changed the mode of failure at the insulation facer level. The current NBCC states that the extrapolation meth- od for roof securement may be used when determining wind uplift resistance for low sloped roof assemblies. Although, designers should exercise caution when relying upon the extrapolation methodology and should consider the mode of failure when determin- ing if extrapolation is appropriate for use on each speciﬁc project. It should also be noted that this issue has become an item of concern amongst experts within the rooﬁng industry and is currently being investigated further to determine if extrapolation for adhesive spa- cing is acceptable in combination with CSA A123.21 testing. In addition, upon review of the supplied testing reports and discussion with the manu- facturer, the assembly was noted to have been tested in a facility that was reported to have not completed voluntary Special Interest Group on Dynamic Evaluation of Rooﬁng Systems (SIGDERS) calibration of their laboratory testing equipment, choosing instead to use an alternative method of cali- bration. While the SIGDERS calibration is voluntary at this point per code, it is prudent to note that any testing methodology that lacks an industry accepted calibration meth- odology is questionable. CONTRACTOR’S RESPONSIBILITY The general contractor and rooﬁng trade have a responsibility to install the rooﬁng assembly as per the manufactur- er’s instructions, matching the design of the rated roof assembly while maintaining quality control. At the project, several deﬁciencies were noted including incorrect application of ad- hesives contrary to spacing and bead require- ments. Adhesive was applied in a haphazard manner and numerous insulation panels were observed with insufﬁcient amounts of adhesive applied. Timing of installation of the subsequent layer upon adhesive appli- cation was questionable, as delays in instal- lation of the subsequent layer may have re- sulted in skinning over of the adhesive. Adhesive was stored on the roof in winter conditions and subjected to below freezing temperatures, including many of the adhes- ive containers observed to have been covered with snow. Although the adhesive was warmed each day before use in a heated construction box, the quality and the performance of the n n n FEATURENext >