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Z.3A Eco -Roof <br />Facility Descrtntlon <br />Eeo-Roofs are impervious area reduction <br />techniques. Eco -Roofs are vegetated roof systems <br />used in place of conventional roofs. Eco -roofs <br />provide stormwater management by capturing, <br />filtering, and, depending on the season, evapo- <br />transpirates precipitation while providing <br />aesthetic and energy conservation benefits. <br />Eco -Roofs meet the stormwater management <br />standard imperious area reduction techniques. <br />Eco- Roofs replace impervious area at a 1:1 <br />ratio. They are not allowed to receive water from <br />other impervious areas. . <br />51°Fe: Maximum roof slope shall be 25% unless <br />the applicant can provide documentation for <br />runoff control on steeper slopes. <br />Drain: As with a conventional roof; an Eco -Roof <br />must safely .drain runoff from the roof to an <br />approved stormwater destination. <br />)Materials <br />Structural Roof Sunnort: The structural roof support must be sufficient to hold the <br />additional weight of the Eco -Roof. For retrofit projects, check with an architect, structural <br />engineer, or roof consultant to determine the condition of the existing building structure <br />and what might be needed to support an taco -Roof. This might include additional decking, <br />roof trusses, joists, columns, and/or foundations. Generally, the building structure must be <br />adequate to hold an additional 10 to 25 pounds per square -foot (psf) saturated weight, <br />depending on the vegetation and growth medium that will be used. (This is in addition to <br />snow load requirements.) An existing rock ballast roof may be structurally sufficient to <br />hold a 10 -12 psf Eco -Roof. [Ballast typically weighs 10 -12 psf.] <br />For New Construction: The project architects and structural engineers shall address the <br />structural requirements of the Eco -Roof during the design process. Greater flexibility and <br />options are available for new buildings than for re- roofing The procedures for the <br />remaining components are the same for both re- roofing and new construction. <br />Waterproof M= = ( Impermeable Material)w Good quality waterproofing materlal must <br />be used on the roof surface. Waterproof membranes are made of various materials, such as <br />modified asphalts (bitumens), synthetic rubber (EPDM), hypolan (CPSE), and reinforced <br />PVC. Some of the materials come in sheets or rolls and some are in liquid form. They have <br />Stormwater Management Manual 2 -11 <br />E ugene 2014 <br />