Stormwater Source Control Design Guidelines 2005 - Waterbucket

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Stormwater Source Control Design Guidelines 2005Green RoofLimitationsGreen roofs must be designed with an awareness of theloading of the roof on the underlying structure. However,use of lightweight growing media has created solutionswhere saturated growing media can be installed withoutstructural upgrading beyond the standard requirements,especially in concrete buildings or new construction. (Peck& Kuhn, 2001).Canada does not have official green roof standards. Untilsuch standards are published, the German FLL guidelinesand test procedures represent the only comprehensivestandards for green roof design, installation andmaintenance. Green roofs, as extensions of the roofingsystem, should comply with the BC Building Code.Extensive Green Roof TypesExtensive green roofs can be one of following designs:• Multiple layer construction (Drawing 5A and 5B) - consistsof either: i) a three-layer system including separatedrainage course, filter layer and growing medium or; ii) atwo layer system where the growing medium is sized to notrequire a filter between it and the underlying drainagelayer. Extensive Green Roof may be installed over either aconventional or an inverted roof system.• Single layer construction (Drawing 5B) - consists of agrowing medium which includes the filter and drainagefunctions.Design Guidelines1. Start the design of the green roof at the same time as thedesign of the building or retrofit project, so that thestructural load of the green roof can be balanced with thestructural design of the building. From the outset, involveall design disciplines – structural, mechanical andelectrical engineers, architects and landscape architects –and include roofing design professionals in a collaborativeand optimization effort (Oberlander et al., 2002).2. Provide construction and maintenance access to extensivegreen roofs. Access through a ‘man door’ is preferable toaccess through a small roof hatch (Peck & Kuhn, 2001).Provide areas of storage for maintenance equipment.Review Workers Compensation Board requirements forsafety of maintenance workers – can gardeners workingnear the edge of the roof use the same harness fasteningsas window washers? (Oberlander et al., 2002) Provide aGreater Vancouver Sewerage & Drainage District65
Green Roof Stormwater Source Control Design Guidelines 2005hose bib for manual watering during establishment if noautomatic irrigation system is planned.3. Roofs with less that 2% slope require special drainageconstruction so that no part of the growing medium iscontinuously saturated. As the slope increases, so doesthe rate of rainfall leaving the roof. This can becompensated for by using a medium with high waterstorage capacity. Roofs with over 20º require specialprecautions against sliding and shearing (FLL. 2002). Ifinverted roof systems are used with exterior insulation,good drainage needs to be provided to prevent continuoussaturation of the insulation, and subsequent damage (Peck& Kuhn, 2001). With inverted roofs, the green roofcomponents must allow moisture to move upwards fromthe insulation and to eventually evaporate (Krupka, 1992).Photo Credit: Lanarc Consultants Ltd.4. Provide plant free zones to facilitate access for inspectionsand maintenance and prevent plants from spreadingmoisture onto exposed structural components. They canalso function as a measure against fire and wind-uplift.They should be at least 50 cm wide and located along theperimeter, all adjacent facades and covered expansionjoints, and around each roof penetration.5. Fire breaks of non-combustible material, such as gravel orconcrete pavers, 50 cm wide, should be located every 40m in all directions, and at all roof perimeter and roofpenetrations (FLL, 2002). Other fire control optionsinclude use of sedums or other succulent plants that havea high water content, or a sprinkler irrigation systemconnected to the fire alarm (Peck & Kuhn, 2001).Newly planted extensive green roofshowing plant-free zones at drain andedges – White Rock Operations Building6. There are several choices of waterproof membranes.Thermoplastic membranes, such as PVC (polyvinyl choride)or TPO (thermal polyolefin) using hot air fusion methodsare commonly used for green roof applications.Elastomeric membranes like EPDM (ethylene-propylenerubber materials) have high tensile strength and are wellsuitedto large roof surfaces with fewer roof penetrations.Modified bitumen sheets are usually applied in two layersand are commonly available. Liquid-applied membranesare generally applied in two liquid layers withreinforcement in between. The quality is variable. A factorin choosing a waterproofing system is resistance to rootpenetration (see point 7 below).7. Provide protection against root penetration of thewaterproof membrane by either adding a root barrier orusing a membrane that is itself resistant to root penetration66Greater Vancouver Sewerage & Drainage District
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Stormwater Source ControlDesign Gui
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Contents Stormwater Source Control
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Acknowledgements Stormwater Source
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Introduction Stormwater Source Cont
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Summary Posters Stormwater Source C
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DESIGN PRINCIPLES■ Maximize the a
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DESIGN PRINCIPLES■ Literature sug
Page 19 and 20: DESIGN PRINCIPLES■ Suitable for f
Page 21 and 22: Introduction Stormwater Source Cont
Page 23 and 24: Rainwater Source Control Around the
Page 29 and 30: Absorbent Landscape Stormwater Sour
Page 39 and 40: Infiltration Swale Stormwater Sourc
Page 43 and 44: FLOWGROWING MEDIUMADJACENT GRADE200
Page 45 and 46: FLOWADJACENT GRADE200GROWING MEDIUM
Page 49 and 50: Infiltration Rain Garden Stormwater
Page 51 and 52: Infiltration Rain Garden Stormwater
Page 53 and 54: 12345678910TREE, SHRUB ANDGROUNDCOV
Page 55 and 56: 1123456789101112TREE, SHRUB ANDGROU
Page 57 and 58: 1RAIN WATER LEADER OROTHER INLET4DA
Page 59 and 60: Pervious Paving Stormwater Source C
Page 65 and 66: 1PERMEABLE PAVERS (MIN. 80mm THICKN
Page 69: Green Roof Stormwater Source Contro
Page 73 and 74: Green Roof Stormwater Source Contro
Page 77 and 78: 1WALL CAP FLASHING9WATERPROOF MEMBR
Page 81 and 82: Infiltration Trench and Soakaway Ma
Page 83 and 84: Infiltration Trench and Soakaway Ma
Page 85 and 86: 1 GRASS OR OTHER PLANTING2FINISH GR
Page 87 and 88: Design, Construction and Maintenanc
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Design, Construction and Maintenanc
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Design, Construction and Maintenanc
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Candidate Plant List Stormwater Sou
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Glossary Stormwater Source Control
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Glossary Stormwater Source Control
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Stormwater Source Control Design Gu
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Key ContactsLast revised 11 April 2
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Key ContactsLast revised 11 April 2
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Key ReferencesKey AuthorBarry, K.,
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Key ReferencesKey AuthorDeutsche Ve
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Key ReferencesKey AuthorHorner, R.R
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Key ReferencesKey AuthorLower Hunte
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Key ReferencesLast revised 11 April
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Key ReferencesLast revised 11 April
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Key ReferencesKey AuthorUnited Stat
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