b'Roof Replacements Art Meets Science: By Michael Hensen, Vice President,Roof replacementsBuilt Environment Solutions, Canada, Rimkus Consulting Group A smanybuildingrestoration consultantsandcontractors willattest,roofreplacement designandconstructionhave evolved substantially in the last 20 years. Contractors or roof designers cannolongerrelyonhabitually selectingfavouriteroofsolutions, andoneroofsystemorassembly can no longer be considered suitable forallbuildings.Thereisno longeronematerialmanufacturer thatcansupplyallthesolutions. Newroofdesignshaveincreased demands from building owners to provideroofsthatoffercomplete sustainablesolutionsandnotjust waterproofprotection.Evolution of Roof Construction PracticesRoofconstructionuptothe mid-1980swastraditionallyapre-dictablepractice.Roofingcrews would leave their place of business to work on projects where the only installation instruction required was how much roof work was expected to be completed that day. There was no question of what type of roof sys-tem was to be installed, no concern about how much or what kind of insulation was required, and no con-sideration of how to ensure continu-ity of the air barrier, vapour retarder tie-ins,adhesiverates,mechanical fastening patterns, material lists and shop drawings. The practice worked well,withroofingcontractorsin-stallingwatertightsolutionsthat wouldtypicallyprovidelong-last-ing, effective results. Roofing tech-nicians were craftsmen often trained through apprenticeship and genera-tional-type training. They were suc-cessful in their trade primarily due to the predictable and repetitive na- Completed modified bitumen ture of working with built-up roofmembrane built-up roof assemblieswithfewvariablesandreplacementapartment building. thesoleobjectiveofkeepingpre- (Credit: Chris Dawson.)cipitation out. There was very little 14ONTARIO ROOFING NEWSISSUE 2 2025 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'