b'Technology Vegetated Roof AssemblyApplying the CAN/CSA A123.24 Standard Test Method for Wind Resistance of Vegetated Roof Assembly for code compliance By Mauricio Chavez and Bas BaskaranThefollowingarticleoriginallyconsensus-basedteststandardsistanceofthemembraneroof- Flow Testingcility set-up includes the airflow appearedintheFall/Winter2021to evaluate VRA wind resistanceingassemblysodeterminedisAccordingtoCSAA123.24- machine,ahorizontalplatform issue of Roofing Canada magazinefordemonstratingconformancean acceptable conservative wind21, the VRA wind flow resistanceand instrumentation to monitor and is reprinted with permission fromto code. As a result, in 2015, theuplift resistance of the VRA. Anyevaluationshallbeconductedthe wind speed and the instanta-theCanadianRoofingContractorsnational standard CSA A123.24- variationinthecomponentsorinanairflowfacilitycapableofneous VRA wind response. Association. 15StandardTestMethodformethodsofconstructionoftheDeterminationofwindresis-generatingahorizontalstream M arket share of VegetatedWind Resistance of Modular Veg- membraneroofingassemblyforflow up to 240 km/h (150 mph).tance of the vegetated system is RoofAssemblies(VRAsetated Roof Assembly (MVRA)which a wind uplift resistance hasestablishedviatwoindicators: was developed. CSA A123.24-15been obtained warrants the windA VRA mock-up is subjected to aa clear visual evidence of failureaka Green Roofs) hasisthefirststandardworldwideuplift resistance of the VRA to bevariety of oblique (45 o ) wind flow(e.g.acomponentoverturning been increasing largely due to thethataddressesthewindMVRAdeterminedinaccordancewithto evaluate VRA response to theor sliding) or when the instanta-claim that VRAs help reduce heatinteraction through a laboratory- CSA-A123.24. most critical conditions. The fa- neous weight of the vegetated sys-islands and reduce water runoff,based test methodology. In 2019, in addition to bringing amenitytomeettherequirementofthe spacesandincreasingbiodiver- green roof industry, NRCC and sityinurbanareas.VRAshavecollaborators completed the VRA been widely used for more thanR&D and delivered a new version twodecades.Valuableinforma- of the standard (CSA A123.24-21 tionandguidancetoensureaStandard Test Method for Wind safeinstallationandadequateResistance of Vegetated Roof As-overall performance is currentlysembly),whichexpandsthe available(ANSI/SPRI-RP-14scope to include the built-in-place (2016),ANSI/GRHC/SPRIvegetated roof assembly (BVRA) VR-1(2011),FM1-35(2007),wind resistance evaluation.FLL (2018), Toronto Green Roof ConstructionStandard).How- Uplift Testingever, it should be mentioned that these documents are only designAccordingtoCSAA123.24-guidelines and offer building offi- 21, the VRA wind uplift evalua-cials little in terms of determiningtion should follow the procedures pass/fail criteria for code compli- describedinCSAA123.21-20 ance verification, in particular forStandardTestMethodforthe resisting design wind forces.DynamicWindUpliftResistance Over the past 10 years, the Na- ofMembrane-RoofingSystems. tional Research Council of Can- However,CSAA123.24-21states ada(NRCC),incollaborationthat: If the wind uplift resistance with the green roof and roofingof the membrane roofing assembly industry and under the umbrellaused in the VRA has already been of CRCA, has been putting forthdetermined in accordance with ofFigure 1: VRA example in Toronto (Photo courtesy of Kees Govers from LiveRoof Ontario Inc.)consistenteffortstodevelopaCSA-A123.21, the wind uplift re-12ONTARIO ROOFING NEWSISSUE 4 2021/22 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'