b'CLASS A ROOFSPhoto Credit: Graham FinchCLASS A ROOFS EXPLAINED: Assemblies, substitutions and compliance BY ROBIN URQUHART, JAMES BOURGET AND GRAHAM FINCH"C lassAroofingisnowato the outermost layer of the roof. Thethe fire tests used to establish a Classfamiliar requirement acrosstest standard title doesnt help with theA rating.manyprojectsinBritishconfusion; the standard is called CAN/ AsClassArequirementsmove Columbia.ItappearsinULC-S107 Standard Methods ofFire Testsbeyond their traditional use in commer-building code discussions, wildfire guid- ofRoofCoverings, but in reality, Class A ance, insurance requirements and devel- is applied to all the components in thecialandinstitutionalconstructioninto opment approvals, and it is often treatedroof assembly above the roof structureresidential and wildland-urban interface asaclearbenchmarkforfire-resistantand is usually referred to as deck-up. (WUI)projects,theseassumptionsare construction.DespiteitswidespreadConfusion is further compounded byincreasingly being tested in the field. This use, Class A remains one of the mostthe assumption that a Class A roof auto- article focuses on how Class A is actually misunderstood aspects of roof design. maticallydeliversotherperformanceapplied in practice: what it means, what Much of the confusion stems fromoutcomes,suchaswindresistance,it does not mean and how responsibility howClassAisdiscussed.Itisoftenimpactresistanceordurability.Thesefor compliance is managed across design treatedasaproductattributeappliedcharacteristics fall outside the scope ofand construction.12 lROOFINGBClSPRING 2026'