b'Technical ArticlecommonlypracticedworldwideDevicesthatuseair-driedties of a life-long, premium roof. and is considered most effective.paintsmayinitiallymatchtheBoth continuous and discontin-Even when the calculation of vec- roof, but the match may be lostuousstylesareavailableinthe tor force indicates that multipleafter a few years of weathering.marketplace.rowsarerequired,thecommonThis is due to inferior fade char- Attaching to the Buildingglobalpracticeistolocatetheacteristicsofair-driedpaintsStructuresnow-retention devices within thewhencomparedtofactory-ap- The second mechanical meth-downslopehalfoftheroofsur- pliedfinishesofmetalpanels.od for mounting snow retention face. Further and exact placementPowdercoatingmayprovideattaches snow guards through the detailsaremorerelatedtoartgreater longevity than air-driedroof and into the building struc-and aesthetics than science. Thepaint in terms of colour stabil- ture. Snow guards attached to the MetalConstructionAssociationity, but it is still not generally (MCA) 3hasmadesomegeneralequaltofactory-appliedpoly- buildingstructureprovidease-recommendations. vinylidenefluoride(PVDF)cure and reliable method of snow Becausethecompressivepanelfinishes.Inthisregard,mitigationiftheyareproperly strength is so great at the snow- thesnowguardsserviceabilitytested, designed, installed and wa-Figure 5: All snow guard devices rely on the compressiveroof interface, snow guard deviceswill not last as long as the roofterproofed (Figure 8).strength of the snowbank, which is greatest at the snow-roofonly a few inches in height havedoes. The best colour-match op- Snow guards that attach direct-interface and at the lower end of the roof. demonstrated success, even whention is a snow guard device thatly to the structure require penetra-snowbanks are quite deep.integrates a slide-in colour stription for anchorage of snow guard ofthesamePVDFcoil-coatedbrackets; hence, weatherproofing Snow Guard Design Concepts material as the roof itself. Thereincludingsealantprotection There are two distinctive snoware several such products com- from ultraviolet (UV) light expo-guarddesignconcepts:continu- mercially available.sure and over-compression of the ous and discontinuous. One typeseal for the long-term service life ofdesignusescontinuoushori- Mounting Techniques of the roofis of paramount im-zontal components assembled lat- portance.Suchweatherproofing erally across the roof in the styleTherearethreetechniquesrequires a high degree of expertise of a fence. Depending on specificformountingsnowretentionindesign,sealantchemistry,se-job conditions and load-to-failuresystemstoametalroof.Twolection/sourcing, application and characteristics of the devices, com- ofthesetechniquesuseme- other areas. If sealants/gaskets are ponents may also be repeated inchanicalattachment.Thefirstnot factory applied by the vendor, parallel rows up the slope of theattaches clamps directly to thethe contractor will be responsible roof, with a greater concentrationroof seam using setscrews thatfor selecting and applying appro-near the eave area. The snowbankdo not penetrate the roof; thepriate waterproofing. creates a bridge between rows tosecondusesfasteningscrewsThe strength of the structural distribute vector loads. topenetratethroughtheroofattachmentmountingmethod The other type of design con- material into the structure. Theshouldbeprovenandmatched sists of small, discontinuous indi- remaining third technique usesto the in-service loads to which vidual units used as cleats, gener- a chemically attached peel-and- the snow guard will be exposed. allyspot-locatedatornearthestickadhesivetapeorpump- Again, testing should be specific eave, or repeated in a pattern pro- able glue. This method is oftento the deck and substrate actually gressing up the slope of the roof.used for individual discontinu- used on the project. These proven This style also relies on the shearous snow guards. holdingstrengthscanthenbe Figure 6: Examples of a fence (continuous) type of snow guard (top) and aand compressive strength within ausedtoscientificallydetermine cleat (discontinuous) type of snow guard (bottom). snowbank to bridge between theClamp Mounting to the appropriate snow guard popu-individual units in both axes.Standing Seamlation for the specifics of the proj-Unfortunately, common speci- The non-penetrative methodect, eliminating guesswork.ficationsdonotalwaysclearlyusing seam-clamping fixity (Fig- This type of snowguard is only identifywhetherthedesignisure 7) is a measurably secure op- suitable for a roof that is attached continuous or discontinuous. Thetion for an SSMR profile, butinthesameway(thatis,with specifier would benefit by break- only when evidence of adequatescrewsthatpenetratetheroofs ing from convention and makingtesting is presented to prove it.surface, attaching it to the struc-this distinction.Whenclamp-mountedattach- ture). It should not be used on an Bothstylesofsnowguardsments are used, the sliding forceSSMR because it violates the de-(fenceandcleatorcon- of the snow is transferred to thesign intent of an SSMR, and fur-tinuousanddiscontinuousclampandthenintotheroofthermore, weatherproofing would styles) have demonstrated satisfac- panelsspecificallytheroofbe challenging.tory performance whenproperlyseams. The holding strength of and adequately tested, engineeredsuch a system should be quan- Using an Adhered Guardand installed (Figure 6). tifiedthroughprudenttestingThethirdtechniquefor andengineeringtoresistthemountingasnowretentionsys-Additional Considerations service loads on any given job.tem to a metal roof uses a stick-on Free Estimates and Proposals Aside from appropriate testingIt is the same force that is act- part (chemical attachment). Some Modified Bitumen Membrane Assemblies for holding capacity, other designing on the SSMR panels at theirvariationsemployafactory-ap-P.V.C. Roofing Membrane considerationsincludeverify- pinned location. plied adhesive and others a field-Protected Roof Membrane Assemblies ingthecompatibilityofmetals,Clamp-to-seamattachmentsapplied one. Adhesive-containing ROQUE ROOFINGRestoration and Renovation Work matching serviceability of the de- can easily be mounted after theproductsareavailableinboth info@roqueroofing.com Roof Evaluations and Reporting vice/system with that of the metalroof has been installed and willplastic and metallic options, but 905-525-9689Waterproofing Systems panels,andcolourmatching(ifnot fatigue due to thermal heat- in discontinuous styles only. required). The objective is to se- ing or cooling of the roof. Pro- At first glance, stick-on snow lect a system that will perform sat- vided correct quality checks areguard systems appear to be very isfactorily for the life of the rooffollowedinproductselection,convenientandeasytoinstall. while doing it no harm. theywillpreservethewarran- However,acloserlookdetails 20ONTARIO ROOFING NEWSISSUE 3 2021 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'