b'there is no air available to enter the assembly and fill the volume under the billowed membrane, effective-ly acting as suction from below to keeptheprimarymembranein place. Want to try this for your-self? Take a Ziploc bag, remove all of the air and seal it tight. Now try to pull the two sides apartwith no air to fill the bag, suction will keep the sides from separating.Roof Parapets and CornersWhydoroofparapetsand cornersseemtogetalltheat-tention?Inthissituation,the squeaky wheel gets all the grease. Aswindactsonourbuildings, ithastospeeduptogetover the roof. This increase in speed and upward pressure can be far more destructive than the field of the roof. As air twists and turns aroundparapetsandcorners,it creates a variety of forces capableFigure 5: Isometric view of modified bitumen assemblies test layout. Courtesy of National Research Council of Canada.ofmovingballastandworking loosemembranesfree.Italso happens at a location where the wall-to-roof air barrier is difficult to detail and is subsequently at aCodes, Standards and aresistance of membrane-roof- placement,realizethatthereareings and avoiding the negative results higher risk of air leakage.Little Something Extra ingsystems many factors that contribute to theof uncontrolled air leakage. Always At this critical point of mem- Currently in Canada, the fol- There are also some very inter- long-termperformanceofabuild- bring in building science and build-brane connection, air leakage canlowingreferencestocodesandestingdocumentsthathavebeeningsroofsystem.Considerthataingenvelopeprofessionalstoassist beproblematic.Itcanprovidestandards help to address air bar- prepared by the National Researchroof is not a standalone element ofyou in your design. Pay close atten-the weak link in the envelope thatriersandroofingassembliesforCouncil of Canada that outline theyour building, but an integral part oftion to the available codes, standards damagingwindscanexploit,re- thedesignandconstructionofresults of air leakage testing on vari- the building envelope that deservesand important work that is done by sulting in roof blow-offs and otherourbuildings: ous types of low-slope roofs: the same consideration we pay to theour research community and trade major failures. It can be a point of1.NationalBuildingCodeof1.Mechanically Attached Singlewalls and other critical parts of theorganizations. And, if nothing else, major infiltration and exfiltrationCanada Single-Ply and Polymer-Modi- building. By considering the effects and,dependingonthetempera- fied Bitumen Roof Membraneof all forms of air pressure on ourunderstandthatairleakageisnot a.ProvincialBuildingAssemblies,ReportNo:A1- buildings, we will be one step closerjust a wall thingits a whole build-tures, can become a major sourceCodes 004336.1 to achieving resiliency in our build- ing thing.of condensation. Condensation ofi.Part9:Small2.AIRMovementImpactson this proportion can often be mis- Buildings RoofingSystems[AIR]Part takenforroofmembraneleaks.ii.Part5:Environ- 2ImpactofAirIntrusion This condensation can affect notmental Separation onMoisturePerformance only the roof, but also the walls2.CAN/ULC-S741-08,Stan- ofMechanicallyAttached andcladdingsystems,especiallydard for Air Barrier Materi- Roofing Systems, Report No: thosesusceptibletothefreeze- alsSpecification A1:004336.2thaw action of water like masonry3.CAN/ULC-S742,StandardA key takeaway from these doc-and other cementitious materials.for Air Barrier Assemblies uments is that the key to successfulThink Safe,Specialattentiontothede- Specification air leakage performance in roofingWork Safe,tailingoftheairbarriershould4.ASTM E2178-21a, Standardis in part the attention to detailingsince 1988be made during the roofing pro- Test Method for Determin- of the membrane at seams, penetra-cess. As roofing is often the firstingAirLeakageRateandtionsandperimeterterminations.Top-Line Roofing & Sheet-Metal Inc. specializes membranesystemputinplace,CalculationofAirPerme- Itisnoteworthythatthereportsin the installation, repair, and maintenance of it is important to include for theance of Building Materials donotlookatperformancedif- industrial roofs throughout Southern Ontario. 5.ASTME2357-18,Standardferences between wind uplift testsOUR SERVICES:supplyandinstallationofaro- Test Method for Determin- with a self-adhered air and vapourCommercial roofing Re-roofingbust and transition material thating Air Leakage of Air Bar- barrier as part of the assembly vs.Roof maintenance Skylight installationwill allow for the connection ofRoof inspection,Sheet metal flashing, rier Assemblies that without. As you look throughevaluation & report fabrication & installationthe air and vapour barrier of the6.ASTME3158-18,Standardmanufacturers listings of their test- Historical restoration Retro-fit curb installationroof assembly to the main roof- Test Method for Measuringed systems, you may find evidenceEmergency roof repairsing membrane, as well as the walltheAirLeakageRateofathat systems tested with an air and air barrier system. This approachLarge or Multizone Building vapour barrier at the structure level(905) 602-0760will help avoid difficult-to-detail7.CSAA123.21:14(R2019),perform better than those without. 1325 Fewster DrMississauga, ONL4W 1A2situations that may result in airStandardtestmethodforAs you begin to consider yourtoplineroofing.cabarrier leakage. thedynamicwindupliftnextbuildingsroofdesignorre-ORN THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ONTARIO ROOFING NEWSISSUE 4 2023/2423'