b'TECHNOLOGYDesigners may set greater building-specific wind loads thanlaugmentationdescharges).Cettespcificationauraune those provided by NBCC Subsection 4.1.7 or Wind-RCI (forincidencesurlescotsdeconstruction,carilfaudrades increased safety or anticipation of increasing future loads). Thistoitures plus robustes. Mais tant que la spcification indique will most likely have an impact on the cost of construction asclairementleschargespourchaquezonedecouverture, more robust roofing assemblies will be required. But as longlappel doffres se droulera sur un pied dgalit.asthespecificationisclearlyindicatingthewindloadsfor each roof zone, the bidding process will take place on an evenRle du fabricantplaying field. Lesfabricantsquisouhaitentquelesentrepreneurschoi-sissent leurs systmes doivent obtenir des rapports dessai Manufacturers role dmontrant la rsistance au vent. Ces rapports sont publis Manufacturerswishingthatcontractorsselecttheirroofingparundeslaboratoiresdessaiagrspourexcuterles assemblies in bids must obtain test reports demonstrating theprocdures CSA A123.21.resistance to wind uplift of these assemblies. Such reports areLes deux procdures de la norme CSA A123.21 exposent issued by one of the testing laboratories accredited to performun spcimen de toiture, install sous une grande soufflerie, the CSA A123.21 procedures.une srie de charges de soulvement simulant laction du Both procedures present in CSA A123.21 expose a roofingvent. Pour les toitures o la membrane est fixe mcanique-assembly specimen, installed under a large vacuum chamber,ment au platelage structural, le spcimen doit demeurer intact to a series of uplift loads simulating the action of wind on aaprs avoir t exposau moins 2 200 charges successives building. For roofing assemblies where the roof membrane isdestinesreproduiredesrafales.Pourlesassemblages mechanicallyattachedtothestructuraldeck,thespecimenolamembranedecouvertureestcolleunsupport must remain intact after being exposed to a minimum of 2,200solide, la norme exige que le spcimen supporte au moins successive loads intended to replicate wind gusts. For assemblies875 charges.where the roof membrane is adhered to a solid substrate, theLa rsistance dun ensemble de couverture sera calcule standard requires the specimen to sustain a minimum of 875partirdelapressionmaintenuependantlaprocdure loads without damage. A123.21,rduiteparunfacteurdescuritappropri. The resistance to dynamic wind uplift of a roofing assemblylheure actuelle, la norme exige lutilisation dun facteur de willbecalculatedfromthepressuresustainedduringthesret de 1,5, mais des travaux sont en cours par lentremise A123.21 procedure, reduced by an appropriate safety factor.du consortium SIGDERS pour saligner avec la rcente tran-Currently the standard requires the use of a safety factor of 1.5sition des charges de vent dans le CNBC de la conception but work is under way through the SIGDERS consortium todes tats limites de service (SLS)la conception des tats align with the recent transition of wind loads in NBCC fromlimites ultimes (ULS). Une nouvelle dition de la norme CSA serviceability limit states (SLS) design to ultimate limit statesA123.21 devrait tre publie (probablement en 2020) et un design (ULS). A new edition of CSA A123.21 is expected to befacteurdersistanceremplaceraprobablementlefacteur published (probably in 2020) and a resistance factor is likely tode scurit.replace the safety factor. Un rapport dessai unique peut comprendre plus dune A single test report may include more than a single resistancevaleur de rsistance pour un ensemble de couverture donn. value for a given roofing assembly. This will be the case whenCe sera le cas lorsquun fabricant choisira de tester la mme a manufacturer chooses to test the same basic roofing assemblytoiture de base en deux variantes ou plus. Ces variations in two or more variations. Such variations include differenttouchent lespacement et le calibre des attaches, lespace-fastener spacing, different fastener gauge, different adhesivement des rubans adhsifs, etc. Dans le rapport dessai, la ribbon spacing, etc. In the test report, the resistance of eachrsistance de chaque configuration teste sera indiquetested configuration will be indicated next to the appropriatect de la variation approprie. Certains rapports indiqueront variation. Some reports will also indicate optional components,galement des composants facultatifs dont la prsence nin-the presence of which will not influence the uplift resistance offluera pas sur la rsistance au vent.the assembly. Les rapports sont disponibles auprs des fabricants, des Testreportsareavailabledirectlyfrommanufacturers,laboratoiresdessai,desassociationsdentrepreneursen testing laboratories, roofing contractors associations and public databases such as Central Roof Reference (www.crt-csa.ca) etc. couverture et des bases de donnes telles que Centrale de rfrence de toiture (www.crt-csa.ca), etc.Contractors roleUsingthewindloadsprovidedbythedesignerintheRle de lentrepreneurspecification (one for each roof zone) and CSA A123.21 testEn utilisant les charges de vent prescrites dans le devis (une reports from manufacturers showing uplift resistance results,pour chaque zone) et les rapports dessai CSA A123.21 des contractorsareresponsibleforputtingeverythingtogetherfabricants,lesentrepreneurssontresponsablesdetout andidentifyingaroofingassemblymeetingallclausesofprendre en compte et didentifier un assemblage de couver-the specification. ture rpondanttoutes les clauses de la spcification.Different strategies may be used by the contractor attemptingLentrepreneur peut avoir recoursdiverses stratgies. to win the bid. For example, lets pick a specification requiringPar exemple, prenons un devis exigeant une toiture fixe 44 ROOFING CANADA FALL/WINTER 2019'