b'BUILDING CODEmembrane is bonded to a smooth, rigid surface (e.g., a concrete deck or a steel deck overlaid with a smooth board). It is then covered with a loose-laid drainage board,oneormorelooselayersof insulation(offsetandstaggeredfor optimal thermal resistance), filter fabric, a second drainage board (optional) and gravelballastorpaversonpedestals. The filter fabric corrals the insulation and promotes rafting so that individual panelsarentdisplacedbybuoyancy, intheeventtheprimaryroofdrains become blocked or the roof is not suffi- Vegetated roof systems are also vulnerable to Specified Wind Loadsciently sloped to drain. Ballast(whichmaybegravelor pavers) serves two purposes on this type Roof Consultingof assembly: to resist flotation and to resist SWLs. You may wish to consult theinsulationmanufacturerfortheir ballastrecommendations,oryoucan refer to the ANSI/SPRI RP-4 Standard, WindDesignStandardforBallasted Single-plyRoofingSystems.Also,referto the RCABC Roofing Practices Manual for ballasted system securement in Part 3 of the specific membrane standard, and be sure to adjust parapet heights to resist wind scour and keep ballast on the roof.Finally,awordaboutgreenroofs, also referred to as living or vegetated roof systems (VRS). Vegetated systems are vulnerable to SWLs, which can be calculated using Division B, Part 4, or with the NRCs web tools (Wind-RCI, or the more recent Wind-VRS). System securement will still rely on measured roof zones; these are used as a buffer to reduce wind loads on the VRS. However, if the VRS is a pre-engineered system (acommonoff-the-shelfsystem thatcomeswiththeentirepackageRoof Condition Assessments & Surveysofcomponentmaterials),checkwithRoof System Design & Contract Managementthemanufactureraboutwindtesting;Green Roof Designseveralpre-engineeredsystemshaveWarranty & Maintenance ReviewbeenwindtestedusingCSA-A123.24,Infrared ThermographyRoof Access & Fall Protection - Design & TestingStandard test method for wind resistance of Roof Asset Management & Capital Planningvegetated roofassembly, and test reports areRCABC Approved Observerslikely available.When the shoe doesnt fit Creative Thinking Practical ResultsOn occasion, it may be impossible to find a suitable tested assembly withaVancouver & Surrey 604-738-0048 Victoria 250-386-7794 rjc.caDUR high enough to exceed the calcu- Nanaimo 250-716-1550Kelowna 778-738-1700lated SWLs for a given project. When www.rcabc.org l29'