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− | The green roof media used in Ontario can be classed according to proportion of composted biological material. Some existing installations use materials which comply with FLL guidelines, whilst others use a much higher proportion of [[compost]]<ref>Hill, J., Drake, J., and Sleep, B. (2016). “Comparisons of extensive green roof media in Southern Ontario.” Ecological Engineering, Elsevier B.V., 94, 418–426.</ref>. | + | The [[green roofs|green roof]] media used in Ontario can be classed according to proportion of composted biological material. Some existing installations use materials which comply with FLL guidelines, whilst others use a much higher proportion of [[compost]]<ref>Hill, J., Drake, J., and Sleep, B. (2016). “Comparisons of extensive green roof media in Southern Ontario.” Ecological Engineering, Elsevier B.V., 94, 418–426.</ref>. |
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| ASTM International have a number of standards relating to various design considerations for green roofs. These standards provide good technical advice on the testing of systems and components. | | ASTM International have a number of standards relating to various design considerations for green roofs. These standards provide good technical advice on the testing of systems and components. |
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| When these tests are completed, the results should be interpreted in relation to the objectives of the green roof. A product complying with overseas guidelines may not serve the needs of a green roof installed in Ontario. In particular, the [http://www.fll.de/shop/english-publications/green-roofing-guideline-2008-file-download.html FLL guide] recommends green roof media specifications which may not provide optimal stormwater management or vegetation in our region. | | When these tests are completed, the results should be interpreted in relation to the objectives of the green roof. A product complying with overseas guidelines may not serve the needs of a green roof installed in Ontario. In particular, the [http://www.fll.de/shop/english-publications/green-roofing-guideline-2008-file-download.html FLL guide] recommends green roof media specifications which may not provide optimal stormwater management or vegetation in our region. |
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| In many proprietary systems the default option for planting medium will be a granular material with very low organic matter content. However, many companies can arrange for a high [[organic matter]] alternative to be substituted if requested. | | In many proprietary systems the default option for planting medium will be a granular material with very low organic matter content. However, many companies can arrange for a high [[organic matter]] alternative to be substituted if requested. |
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| {|class="wikitable" | | {|class="wikitable" |
− | |+ Considerations for using a 'high organic' planting medium | + | |+ Considerations for using a 'high organic', [[compost]] based planting medium |
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| !Benefits | | !Benefits |
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| *Increased water holding capacity, which benefits both vegetation health and stormwater retention | | *Increased water holding capacity, which benefits both vegetation health and stormwater retention |
− | *Often lighter weight, even when saturated | + | *Lighter weight, even when saturated |
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| *Increased [[phosphorus]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall | | *Increased [[phosphorus]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall |