b'Technical Articledor and incorporate the tested ul- Other Keys to Successtimate strength of the system withEnforcethespecification!The an appropriate factor of safety ap- absence of specific code mandates plied. 3Insist that vendors provideenables vendors to market unquali-calculationsbeforeproductselec- fiedsystemsandposesaserious tion. Ideally, the vendor would of- potential liability for designers. Re-fer a web-based calculator with real- quire the vendor to provide a writ-time output showing calculationsten statement of compliance with and allowable loads specific to thethe MCA documents referenced in project, including product nomen- this paper. 2; 3clatures of the snow guard system and specific profile nomenclaturesConclusionoftheroofmanufacturer(FigureMetal roofs are known for theirFigure 9: Adhesives for adhered snow guards diminish in holding capacity over time when exposed on a roof. Examples of three generations of 11).Totheauthorsknowledge,durability, sustainability and versa- adhered snow guards are demonstrated on this roof, which was eight years old at the time of this photo. The Generation 1 example is yellowed with only one vendor in North Americatility. However, because metal roofsage, the Generation 2 examples are not as yellowed, and the Generation 3 example is absent after failure of a Generation 2 snow guard.offers this type of calculator. are slippery, there is a potential for At a minimum, design profes- rooftop avalanches in the discharge sionalsandconsultantsshouldareasbelowtheeaves,causing requirethesecalculationswithpropertydamage,personalinjury submittals. Even better, the designand even death. professional or consultant shouldA scientifically tested and engi-requirebyspecificationthattheneered snow retention system me-calculations be stamped by a reg- chanicallyresistsslidingsnow,so isteredprofessionalengineerwhothe build-up of snow and ice on a has reviewed them. roof evacuates in a predictable and Proof of Certified Manufacturing controlled fashion rather than by a Itiscriticaltoknowthatthesudden release. product purchased is the same asTodeterminethebestsnow the one that was tested. The pur- guardsystemforyourmetal(or chased components may look theotherslippery)roof,youshould same as the tested ones, but alloys,understand the art and science be-tensilestrength,yieldandotherhind snow retention systems and,Figure 10: Examples of adhesive bond to paint. Even if the adhesive does not fail, the paint adhesion might, leading to corrosion.mechanicalpropertiesshouldbemost importantly, vet the manufac-verified through certified manufac- turer and its product offerings.turing with third-party audits in anWhen designers and consultants ISO 90016-compliant facility. 3Askdonotthoroughlyvetvendors to see the current ISO certificate.and submittals, the snow retention Ideally, it should be displayed onsystems they select may fail, even the vendors website.when installed to the manufactur-ers instructions. Such failures leave Warranties the designer and contractor in a po-It is important to verify that thesition of arguing over liability. Sys-manufactureroffersameaning- tem failure can threaten anything fulperformance (notjustmaterial)on the ground below and can also warranty. To do so, obtain a copydamage the roof. Protection from beforespecificationandreadthis liability starts long before the thefineprint!Ideally,thewar- project is bid. ranty should be displayed on theA smart and rather low-cost in-vendors website. When reviewingvestment in a snow retention sys-the warranty, consider whether thetem specific to the projects metal vendor will be in business for theroof profile protects not only the long term to honour it, if needed.roofandroofelementsbutalso The number of years that the com- the rest of the building and its oc- Figure 11: Typical output sheet from valid calculation.pany has been in business is irrel- cupants, as well as pedestrians, ve-evant.Thecriticalquestionsare:hicles, equipment and landscapingREFERENCES metal-roof-design-for-cold- brationLaboratories.Geneva, Has the vendor substantiated itsbelow. An effective snow retention1. PeterKuipersMunneke.climates. Switzerland: ISO.track record for this system in par- system reduces short-term and long- 2009. Snow, Ice and Solar Ra- 3. MCA.2018.Qualifying6.ISO.2015.ISO9001:2015: ticular? On how many projects hasterm maintenance costs and, mostdiation.PhDthesisUtrecht,SnowRetentionSystems.Quality Management Systemsthe system in question been prov- of all, reduces potential liability forThe Netherlands; Institute forMCATechnicalBulletin.Requirements.Geneva,Swit-en effectiveand for how long?building owners and designers.Marine and Atmospheric Re- https://metalconstruction. zerland: ISO.search Utrecht (IMAU); De- org/view/download.php/ Rob Haddock is director of the Metal partment of Physics and As- online-education/education- Roof Advisory Group Ltd. The inven-materials/roofing-education- tor of S-5! attachment technology, he is tronomy, Faculty of Science. al-materials/metal-roofing-Serving Southwestern Ontario Since 1972 2.Metal Construction Associ- snow-retention. a former contractor, an award-winning ation (MCA). 2019. Metal4. County of Los Angeles. 2020.roofforensicsexpert,author,lecturerCommercial RoofDesignforColdCli- RB12;ResearchBulletin,and building enclosure scientist. He is aIndustrial mates.MCATechnicalCounty of Los Angeles, CA. recipient of the IIBEC Richard Horow- Maintenance Specialists Bulletin.https://metalcon- 5. I nternationalOrganizationitz, ASTM D08 Carl Cash and Con-Free Estimates / Inspection struction.org/view/down- forStandardization(ISO).structionSpecificationsInstituteBen 152 Thames Rd. W., Exeter, Ont. N0M 1S3load.php/online-education/ 2017.ISO/IEC17025:2017:John Small awards for his writings and Tel: (519) 235-2802Fax: (519) 235-1532Email: speat@hay.net education-materials/roof- GeneralRequirementsforthehas worked in various aspects of metal ing-educational-materials/ Competence of Testing and Cali- roofing for nearly five decades.22ONTARIO ROOFING NEWSISSUE 3 2021 THE ONLY SOURCE FOR PROFESSIONAL ICI ROOFING CONTRACTORS IN ONTARIO ORN'