b'CLASS A ROOFScode requirements related to wind uplift,TheclassificationappliesonlytotheMISCONCEPTION #2: YOU CAN SWAP moisture control or energy performance. configuration that was tested. ChangingCOMPONENTS IN A CLASS A ASSEMBLYThisoverlapcreatestensionwhenthe deck type, insulation placement orOnce Class A is understood as an assem-ClassAistreatedasasingle,defini- evenmembranescanmateriallyaffectbly-level rating, a second misconception tiverequirementratherthanoneoffire performance. often follows: that components can be severalparallelperformancecriteria.Put plainly, there is no such thing asswappedfreelyaslongastheoverall Resolving that tension requires coordi- a Class A product in isolationonlyintentremainsthesame.Inpractice, nation across disciplines, not reliance onClass A assemblies constructed exactlythis assumption is a common source of classification alone. as tested. non-compliance.WHERE CLASS A ROOFSARE TYPICALLY SPECIFIEDHistorically,ClassAroofassemblies havebeenmostcommonincommer-cialandinstitutionalbuildings,where low-sloperoofsovernon-combustible decks are common and assemblies are highlystandardized.Inthesecontexts, substitutionsarerareandacceptance pathways are well understood.Class A is also widely used in light commercialandmulti-unitresidential construction,particularlywherebuild-ingsarecloselyspacedorinsurance requirements apply. More recently, Class A has become a frequent requirement inWUIresidentialconstruction(see RoofingBCmagazine,summer2025 issue),whereslopedroofassemblies over combustible decks and project-spe-cific detailing are more common. Unlike manycommerciallow-slopesystems that are routinely installed as manufac-turer-definedassemblies,residential slopedroofingisoftenprocuredand installedasacombinationofcompo-nents(roofcovering,underlayment, accessorymembranes,flashings)that maybesourcedseparately.Thisshift increases sensitivity to substitutions and places greater emphasis on coordination during design and construction. MISCONCEPTION #1:CLASS A IS A PRODUCT RATINGOneofthemostpersistentmiscon-ceptions in roofing is that Class A is anTRS BUILDING inherentpropertyofaroofcovering.ENVELOPE CORP.TermssuchasClassAshingleor Class A metal roof are widely used,TOMTAR ROOFINGbut they oversimplify how fire classifi- & SHEET METAL LTD.cations actually work and may mislead designers into thinking that they are theUnmatched Industry Experience.only requirement to achieve a rating.Class A ratings are assigned based onServing the Interior & Western Canadafire testing of a complete roof assembly. www.rcabc.orgl17'