b'climatic loads and how to incorporate them into the experi mental methodology. Initially, hourly temperature time series available for 564locations across Canada were analyzed for hourly fluctuations. The data available for these locations spanned 10 to 20 years, with the majority of the locations having 15 years of data available. A threshold value of 5C was chosen to identify the instances of hourly fluctuations above the threshold. The number of these cycles per year obtained from the time series were fit to a Poisson distribution (probability of exceed-ance is 2%), and the number of cycles for 50-year return periods was deter mined. For the analyses, the period from May to August was considered summer, during which a hot-weather shock would occur, and the period from December to March was winter, during which a cold-weather shock would occur. The above is summar ized in Fig. 28.The hot-and cold-weather shock values are Figure 22. Failure modes varied with curing time for an adhesive applied membraneinitially obtained based on air temperature. Technical Article roofingsystem. The surface temperature that a roof component will reflect under a specific air temperature will differ based on the component and its climatic loads and how to incorporate themposition within the system. That is why there is into the experimental methodology. Initially,a need to establish the relations hip between hourly temperature time series available forthe component temperature and the air 564locations across Canada were analyzedtemperature.for hourly fluctuations. The data available forThereafter, the hot- and cold-weather shocks these locations spanned 10 to 20 years, with thethe component will be experiencing in a majority of the locations having 15 years of datascenario of 2C global warming magnitude available. A threshold value of 5C was chosencan be determined. This framework can be to identify the instances of hourly fluctuationsfollowed for all building envelope components above the threshold. The number of these cyclesand is not limited to roof components. As well, per year obtained from the time series were fitthe param eters can be established for other global warming magnitude ranges from 0.5C to a Poisson distribution (probability of exceed- to 3.5C.ance is 2%), and the number of cycles for 50-year return periods was determined. For the analyses,Q22: CAN I APPLY WEATHER the period from May to August was consideredSHOCK PARAMETERS FOR summer, during which a hot-weather shockDURABILITY EVALUATION OF Figure 23. Condensation below the roof membrane.Figure 23. Condensation below the roof membrane.would occur, and the period from December toROOFING COMPONENTS?March was winter, during which a cold-weatheroverturningandMaterials are currently evaluated at lab roofing assembly consists of a deckincludesliding,temperatures. Materials age and deteriorate shock would occur. The above is summa rized in and roofing or waterproofing mem- scouring (Fig. 26). Responses of the brane. It includes components suchvegetatedsystemtowind-induceddifferently when they experience weather Fig. 28.as vapour barriers or retarders, insu- pressure include fatigue and uplift. shock cycles. Using the information from the The hot-and cold-weather shock values are lation, cover board, etc. A modularframework in Fig. 28 the hot- and cold-weather initially obtained based on air temperature. Figure 22. Failure modes varied with curing time for an adhesive applied membranevegetatedsystemconsistsofpre- Q15: Is There a Tool orshock component temperatures and their Figure 22. Failure modes varied with curing time for an adhesive applied membrane roofing system.roofingsystem. The surface temperature that a roof componentrespective number of occurrences are deter-grownorpre-cultivatedvegetationStandard Available to will reflect under a specific air temperature ofcuringtime.Thesystemhadacannot escape to the exterior envi- cally Attached Roof Assemblies, was(modules, blankets or mats), growthValidate My VRA Design? mined. Also, to replicate the cycling that already media, a root barrier, pavers andnt and its wind uplift resistance of 3.59 kPa (75ronmentwiththeroofmembranedeveloped in 2011. A series of testswill differ based on the componeaThe wind uplift resistance of thenaturally occurs with the change in seasons, the drainagesystem.Inindustryprac-psf) with 21 days of curing time andactingasanairbarrier.Airintru- were carried out by the SIGDERSposition within the system. That is why there ishot- and cold-weather shocks were alternated. tice,aVRAissometimesreferredVRA can be evaluated in accordance a wind uplift resistance of 4.31 kPasion can be a major driving force forconsortium to quantify air intrusiona need to establish the relation ship betweenA123.24,Stan- An important step for incorporating the weather toasagreenroof.However,thewithCAN/CSA term green roof can be misleadingdardshock framework into testing is the duration of (90 psf) with 28 days of curing time.movement of moisture in the formrate for a MARS. The result showedthe component temperature and the airTest Method for Wind Resis-The failure modes for 14, 21 and 28of water vapour into a MARS. Fig.the system with a VB decreased thebecause it can be interpreted differ- tanceofVegetatedRoofAssembly.the hot and cold cycles to ensure practicality of temperature.days are adhesive failure between the23 shows the condensation happen- air intrusion volume by 50 per centently, as follows: The test results can be compared tothe experiments. An example of how this can Thereafter, the hot- and cold-weather shocks cap and base sheet interface, a cohe- ingbelowtheroofmembraneonto80percentdependingontheGreen roof could be a refer- the calculated design parameters inbe achieved is by setting a practical duration ofsive failure between the cap and basebubble pressure (the pressure on thethe component will be experiencing in a one of the commercial roofs duringFigure 24.ence to the color of the roofQ4 above for pass/fail scenarios. the entire weather shock cycle and adjusting the Air intrusion volume with and without the vapor barrier.sheet interface and the VB detachedfieldinvestigation.Limitingairin- top of the insulation/cover board),scenario of 2C global warming magnitude (e.g., a copper roof).from the deck interface, respectively,trusion is critical for good roof de- membranedeflectionandvolumecan be determined. This framework can be GreenroofisusedlooselyQ16: Why Are VRAsas shown in Fig. 22. change, as shown in Fig. 24.IIBEC InterfaceJanuary 2025sign practice; it helps increase wind18followed for all building envelope comp jecte ts to denote roofs with environ- Sub onen d to Uplift and mentallyfriendlyproductsFlow Resistance Tests?uplift and thermal resistance, mini- and is not limited to roof components. As well, Q12: Is There an ImpactmizemoistureaccumulationandQ13: What Are thesuch as those made from recy-the parameters can be established for othertest only evaluates the of Air Intrusion on a Low- condensation issues. Attributes of a Vegetatedcledmaterials(e.g.,bio-basedAn uplift pressure resistance of the VRA, since global warming magnitude ranges from 0.5C Slope Roof? BasedonSIGDERSsresearch,Roof Assembly (VRA)? insulations). the membrane acts as an air barrier in ASTMD7586,StandardTestIn a VRA, a roofing system andto 3.5C. withenergy-efficienta conventional roofing system. Wind Roofs Airintrusioniswhenthecon-ditioned indoor air enters into theMethodforQuantificationofAiravegetatedsystemareassembledcomponentssuchashighlyflowaerodynamicscansimulate reflectiveroofingmembranes buildingenvelopeassemblyandIntrusioninLow-SlopedMechani- together,asshowninFig.25.AQ22: CAN I APPLY WEATHERsystems overturning, (e.g., white single plies or MBthe vegetated SHOCK PARAMETERS FORand sliding failure mecha-roof with reflective coating). scouring nisms. To mimic the wind effects on DURABILITY EVALUATION OF Figure 23. Condensation below the roof membrane. wall siding. The a VRA is define ors that must be Based on this,refore, the fact dthe VRA (refer to Q14), both uplift ROOFINGlacementofanen- TS?asintentionalp COMPONENrespected when determining the composition of Materials vegetatedsystemovertheand flow testing are needed.gineered are currently evaluated at lab the cycles are:roof system (Fig. 25). Q17: Can I Use the Wind temperatures. Materials age and deteriorate The cold and hot component weather shock differently when they experience weather Q14: How Does a VRAUplift Data from a Roof temperaturesshock cycles. Using the information from the Respond to Wind? System Test?The number of weather shock occurrencesframework in Fig. 28 the hot- and cold-weatherascenariowherethe WindaerodynamicsonaVRAYes,in shock component temperatures and theirhas the same roofing system canbeviewedasaction,whereasVRA Q23: CAN Athe reac- as the one respective number of occurrences are deter- tested under CAN/CSA the response of the VRA is CLIMATE-DEPENDEN A123.21,StandardTestMethod tion. Not all VRAs react to wind inT mined. Also, to replicate the cycling that already a similar manner. The response offortheDynamicWindUpliftRe-DURABILITY INDEX (CDDI) BE naturally occurs with the change in seasons, theAttached a vegetated system depends on sev- sistanceofMechanically DEVELOPED FOR ROOFING hot- and cold-weather shocks were alternated.Systems,the eral factors, such as the membraneMembrane-Roofing An iOMPONENTS? manufacturer or client may choose Cmportant step for incorporating the weather attachmentmethod,vegetation shock framework into testing is the dura le, theresistance data ob-By taking asphalt shingles, for examp tion of type, weight, design and installationto use the uplift the ho I can co edgelained ass ollows. ShinglfromCAN/CSAA123.21. method(e.g., exp cles to en f ondi- acticality of CDD t and be ld cy restraintc ure pr tainede tions). The complex wind dynamicsThen the manufacturer or client has the exp osi ments.d behavior are complex, and comp eri tion an An example of how this can on VRAs can be simplified as effectsto perform only the flow test as per be achieved is by ormance once installed an part attributing perfsetting a practical duratios of due to pressure and flow. Respons- Section 7 of CAN/CSA A123.24 to Figure 25.Roofing system and vegetated system assembled together to form the vegetatedesofthevegetatedsystemtoflowobtain the flow resistance.Figure 24.Air intrusion volume with andether to form the ve apor d roof rier. the entire weathen ihockidual property iting fice lt Figure 25. Roofing system and vegetated system assembled tog without the v getatebarassembly. of a system to ar sndiv cycle and adjuss difthuroof assembly. and inadequate. Developing a science-based 20ONTARIO ROOFING NEWSISSUE 1 2025 indicator that would combine key propertiesORNTHE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO18IIBEC InterfaceJanuary 2025with the exposed climate severity of the material may provide a more com prehensive indicator of the materials long-term performance. The CDDI was developed to accomplish this. The CDDI combines five critical properties: tear strength, overlap strength, fastener pull-through, tensile strength, and granule loss.For each of these properties, the durability factor and importance factor are calculated. The durability factor depends on the propertys reduction in strength after exposure to the climate zone-dependent weather shock protocol. If a prop erty is greatly reduced, that is an indication that the durability of the shingle is low. The durability factor ranges from 0 to 3. A durability factor of 0 is corresponds to reduction in strength greater than 45%, and durability factor of 3 is corresponds to reduction in strength less than 5%. A higher durability value indicates a more durable shingle. The impor tance factor is assigned to each of the five critical properties based on the mode of field failures and indus-try consensus. The importance factor for each property is greater than zero but less than 1, as follows: tear = 0.2; overlap strength = 0.3; fastener pull-through = 0.2; tensile = 0.1; and granule loss = 0.2. By combining the durability factor and the impor tance factor for each of the critical properties, one can determine the classification level of CDDI, which can be either silver (CDDI greater than 2 and less than 3) or Figure 26. Wind aerodynamics and failure mechanisms of a vegetated roof assembly. gold (CDDI = 3).duration of each cycle. This must be achievedare 8 hot- and 6 cold-weather shock cycles. TheQ24: WHAT IS THE IMMEDIATE while ensuring that the total number ofduration of 15 days, along with the breakdown ofNEED FOR COMMERCIAL fluctuations for hot and cold weather shocks is8 hot and 6 cold cycles a day and the duration ofROOFING?maint ained. An example of a dark-colored roofeach cold and hot cycle, can be changed to betterAlterations to existing roofs (AER) have a major covering (asphalt shingle) is shown in Fig.29. reflect the building envelope material beingmarket share compared to new construction. The hot- and cold-weather shock cycle has aevaluated. An asphalt shingle will not absorbIn some regions of North America, AER market total duration of 15 days. Within each day thereand retain heat in a similar manner to a beigeshare is over 70%. AER includes, but is not January 2025IIBEC Interface19'