Environmental Design + Construction - October 2008 - (Page 29) is a method to provide access. Uplift issues should be considered where gravel/aggregate is used, especially at perimeters and corners. The IBC, 2006 Edition, has specific requirements which limit the use of gravel/ aggregate on roof systems. UV and mechanical protection is needed for membrane flashings. The activity on a green roof — from landscaping maintenance to public access — raises the possibility of flashing problems. Figure 2 shows a low parapet flashing detail for a thermoplastic waterproofing membrane for an extensive green roof system. Also, expansion joints should be located above the membrane surface, and ideally they should be above the growth medium. Drainage should be provided within any area on a green roof that is bounded by expansion joints, area dividers or perimeters. Safety and access need to be considered during the design of a green roof system. Many green roofs allow public access; many publicly accessed green roofs are many stories off the ground. The 2006 IBC includes provisions requiring roofs used for roof gardens or assembly purposes be capable of suppor ting 100 pounds-per-square-foot live loads. Walls, parapet walls or railings likely are needed to ensure safety of the users of a green roof. Where access to a green roof is allowed, there needs to be appropriate passage from the interior to the exterior — similar to the access required for a public plaza. Recognize there are additional building code requirements for green roofs that are readily accessible. Safety of maintenance personnel is also a concern. Many landscape contractors are not well versed in rooftop safety. If parapet walls or railings are not provided, should anchorage points or safety rails be provided? Or are temporary safety devices all that is needed for rooftop workers? Do green roofs need to include walkways and footpaths for rooftop maintenance workers? These are not necessarily new questions regarding rooftop access, but with more and more publicly accessible green roofs, safety is being thought of more often. Regarding plant maintenance, is there a water source required on the roof? Some green roof plants may require periodic watering. Because green roofs hold water intentionally, the design loads are larger than more traditional roof systems. Extensive roofs start at 12 pounds per square foot; semi-intensive roofs start at 40 pounds per square foot; and intensive roofs start at 60 pounds per square foot. The structure needs to be able to handle the anticipated design loads. Give your roof a day job. Choosing a solar electric system for your business can lower your electric bill by protecting against rising electricity rates, while adding more clean energy to the grid. For commercial solar systems, flexible energy purchase solutions are available, allowing your company to benefit from solar electricity with little or no up-front cost. Mitsubishi Electric is an industry leader in developing high-efficiency photovoltaic modules that deliver clean, reliable energy. We have made a commitment to protecting the environment and we are proud to use 100% lead-free solder in our solar panels. For more information, please call 714-220-2500 or visit our website: www.mitsubishielectricsolar.com READER SERVICE NO. CR04084Mits.indd 1 173 WWW.EDCMAG.COM/WEBCARD Fall 2008 < Cool Roofing 3/6/08 2:53:56 PM 29 http://www.mitsubishielectricsolar.com http://www.mitsubishielectricsolar.com http://www.EDCmag.com/webcard
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