b'BUILDING CODE(wheretheballastisthesecurementorassembliesusedasareference.tripupthedesignandconstruction againstwinduplift).TheseareactuallyTherefore, roof systems using relativelyprocess.Butnotinthiscase.Article divided into three subcategories definednew materials may not qualify. 5.2.2.2. (Division B) explains what needs withinthetestmethod:MechanicallyThere is more. The candidate roofto be done to design a Code-compliant AttachedRoofSystems(MARS),system should have a history of use onmembrane roof; turning that into a real Adhesive-applied Roof Systems (AARS),one or more buildings similar to the onedesign is answered elsewhere in the Code. andPartiallyAdheredRoofSystemsbeingdesigned.ThisisbecausewindAs we will see in the next article of this (PARS) (a hybrid securement model). Inloadsaredynamicinnature(thatis,series, RoofDesign: from Code to specification, the fourth article in this series, we willthey push and pull with varying inten- what the Code has to say about design explore the use of Tested Assemblies assity and often from varying directions)responsibility may surprise you.part of the roof design process. and these wind loads are often productsRoofdesignisacomplicated busi-How does a roof designer find theseof the buildings context (due to loadsness. Ultimately, good roof design must Tested Assemblies? Membrane manufac- exerted by funneled winds and buildingberootedinacommitmenttotake turers operating in Canada have had theirharmonics).Whenframedthisway,careofeachotherourneighbours. membrane systems tested by accreditedthetestforprovenpastperformanceExperiencetellsusthatdesigningand laboratories. Some manufacturers publishsuddenly looks a lot less appealing. buildingaroofthatisresilientunder the test results online; others will providepressure,toservethosewhowilllive a test report if asked. Some roofing asso- A Third Way and work inside the building it protects, ciationsprovidetoolsforlocatingtestFinally,wehavetoconfronttheulti- simplyistherightthingtodo.As reports.RCABCuploadsreportsintomate question: what if neither a Testeddesigners and constructors, we do more the Roofing Practices Manual and makesAssembly nor an assembly with proventhansimplybuildroofs.Together,we them available for review and downloadpast performance will work? The answercreate safe, habitable communities.directly by the user. is (sort of) in the Notes to Part 5. There,Weve authored the book on great roofing The concept of proven past perfor- provision is made to extrapolate the roofdesign and construction standards. Learn manceisintroducedinSentencesecurement using the ANSI-SPRI stan- more about our RoofStar Guarantee (5)ofArticle5.2.2.2.Tolearnmoredard WD-1 14 . However, that provision isProgramathttps://www.rcabc.org/about it, the reader is directed to Notenot exactly a Get out of Jail Free card.roofstar-guarantee, or visit our Roofing A-5.1.4.1.(5) Past Performance asThe extrapolation is limited to mechani- Practices Manual at rpm.rcabc.org.Basis for Compliance with Respectcally attached systems. It does not apply to Structural Loads. The Note is tootoadheredsystemsoreventohybridAbout the Author:large to reproduce here in its entirety, butsystems(securedwithacombinationJames Klassen is a RoofStar Technical we can summarize it this way: when anof mechanical fasteners and adhesives).Advisorandstaffwriterwiththe assembly exists that has a proven recordFor those, the securement of the roofRoofing Contractors Association of ofresistingthespecifiedwindloads,systemshouldbecustom-engineeredBritish Columbia. As a keen propo-that assembly may be used to satisfy theand may have to be extrapolated fromnentofvegetatedroofs,Jamesserves Code. On the surface, this sounds easy,Tested Assembly data. asaco-chairoftheGreenRoofing and in fact the option of proven pastInformationThink-tank(GRiT), performance has been relied upon byGood Neighbours contributestoeducationandpolicy design authorities as a kind of escapeIn London, UK you will hear an elec- developmentforsustainablegreen hatch to avoid the apparent strictures oftronic P.A. announcement at each stationroof design, and is involved on behalf Tested Assemblies. However, the testin the Tube urging passengers to mindof the RCABC in a collaborative work forprovenpastperformanceismorethe gap between the platform and railwithGreenRoofsforHealthyCities onerous and difficult to achieve than itcars. Gaps trip us up. Where we expecttodevelopgreenroofingprofessional appears. It is also intended, by its place- firm ground, sometimes we find nothing. curricula. He also writes for and manages ment in Article 5.2.2.2., to be an alter- Occasionally,thereappeartobetheonlineRoofingPracticesManual, native to the primary pathway: using agaps in the Codemissing pieces thatparticipatesinnumerousCSAtask Tested Assembly. groupsresponsibleforseveralroofing Therefore, if a conventionally insu- 14 The wind uplift resistance obtained from the teststandards, and is a voting member oflated membrane roof system is expectedmethod in CAN/CSA-A123.21 is limited to configu- the CSA-A123 Technical Committee on rations with specific fastener or adhesive patterns. To to last 25 years, it should have a 25-yearextrapolate the test data to non-tested configurations,Roofing. He is an experienced roofing history to support its use an alternative torefer to ANSI/SPRI WD-1, Wind Design Standard Prac- estimator, a former Occupational Health a Tested Assembly. Furthermore, proventice for Roofing Assemblies, for a rational calculationand Safety professional and independent procedure. However, in using this extrapolation proce-past performance is valid only when thedure, wind loads should be calculated in accordanceinsurance claims adjuster, and has exten-propertiesofamaterial,componentwith the BCBC. NRCs guide for wind design referencedsive experience managing facilities and orassemblyareidenticalorsuperiorabove provides further guidance and examples of windtransportation for a large private school load calculations.Division B, Part 5, Notes to Part 5: to those of the materials, componentsA-5.2.2.(4) Membrane Roofing Systems. in British Columbias Fraser Valley. www.rcabc.org l19'