b'RESILIENCYsincesomemeltingbelowthesnowis likely because of penetrating solar radia-tion that heats up the roof surface; this may produce ice buildup in exposed loca-tions (i.e., near drains), which may inter-fere with the free flow of drainage.The second subject is heat, which the Standard doesnt even touch. At least two issuescometomindconcerningheat. Thefirstregardstemperatureswings, which can promote premature aging of exposed roof membranes. Certainly, oneReflected sunlight off the full-length glazing on this Vancouver roof irreparably damaged the membrane and induced significant blistering, way to reduce the problem is to cover theeven where the membrane had been repaired. Resilient designs for the future must consider the potential for damage caused by reflected membrane. This can be done by designinglight, particularly as climate projections forecast hotter summer days and longer spells of uninterrupted sunlight. (Credit: James Klassen.)the roof as a classic protected (inverted) system, by covering it with pavers or a vegetatedsystem,orbydesigningthe roof as a modified protected system, sometimes referred to as a hybrid insu-lated system. In this case, a conventional roof membrane system is covered with aAVAILABILITY AND FORMATS BITUMAR INC.CANADIAN ASPHALT INC. (MONTREAL) (HAMILTON, ON)drainagematerial,extrudedpolystyrenePRODUCTS BULK BURPAKBULK Barrel (keg)(50 lb bags) (100 lb)insulation, filter fabric and ballast so thatLOW ODOUR oxidized asphaltwith an odour inhibitor (suppressant) without the membrane is shielded from extraor- any added PPA in the oxidation process. T2, T3, T4 T2, T3, T4 T2, T3, T4 T2, T3, T4Benets: Less polluting. The kettles and tankers stay cleaner. Mops last longer.dinary temperature swings. If the struc- Asphalt ZEROpolymerized asphalt with a viscosity tureisnotslopedtodrain,thisdesignequivalent to LOW ODOUR oxidized asphaltT2 T2, T3 NA NAat a lesser temperature.approach could be employed to promoteBenets: savings on propane, less smoke, no odour and improved adhesion.positive drainage with the use of taperedSEBS LOW ODOUR Asphaltelastomeric asphalt with an odour inhibitor insulation within the conventional bottom(suppressant) with a minimal elongation of 750% NA SEBSNA NABenets: The ideal asphalt for the laying of elastomeric membranes and fleece back750system, and may coincidentally improvemembranes as TPO, PVC and EPDM or for a phenomenal adhesion of surface gravel. It can overallthermalperformanceoverthatreplace urethane and glues at a lesser cost.expected from a simple protected roof. 7The second issue concerns the service temperature of heat-sensitive insulation. 8These materials usually have a maximum effective temperature of around 70 C; if the material is exposed to higher tempera-tures,itcanbepermanentlydeformed, leadingtopossiblesystemdistortions and thermal loss. Presently, RCABC stan-dardsrequireheat-sensitiveinsulation be protected by a layer of heat-resistant insulation at least 50.8 mm (two inches) thick,butthatminimumisbasedon modellingusingcurrentclimatedata. 9Thatminimumshouldbeincreasedif heat-sensitive insulation is contemplated anywhereneartheweathersideofthemembrane assembly.RESILIENT WATER-SHEDDING ROOFSAsIsaidearlier,theClimate-RCIweb tooldoesnotyetincorporateperfor-mance computations for asphalt shingle roofs, but that does not mean nothing can bedonetoenhanceresilience.Current www.rcabc.orgl27'