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| + | 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. https://www.sciencedirect.com/science/article/abs/pii/S0925857416302804?via%3Dihub</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. |
| Of particular note are: | | Of particular note are: |
− | *E2399 Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems[https://www.astm.org/Standards/E2399.htm], and | + | *Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems[https://www.astm.org/Standards/E2399.htm E2399], and |
− | *E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms]. | + | *Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms E2396]. |
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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. |
− | 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]].[http://grit.daniels.utoronto.ca/wp-content/uploads/2016/06/Comparisons-of-extensive-green-roof-media-in-Southern-Ontario.pdf]
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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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| + | Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation <ref>MacIvor JS, Margolis L, Puncher CL, Carver Matthews BJ. Decoupling factors affecting plant diversity and cover on extensive green roofs. J Environ Manage. 2013;130:297-305. https://www.sciencedirect.com/science/article/abs/pii/S0301479713006051?via%3Dihub</ref>, however stormwater retention was not improved with this increase in depth <ref>Hill, J., Drake, A. P. J., Sleep, B., and Margolis, L. (2017). “Influences of Four Extensive Green Roof Design Variables on Stormwater Hydrology.” Journal of Hydrologic Engineering. https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0001534</ref> |
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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. |
| *The lightweight material is more prone to wind erosion, and this should be accounted for in the initial design, alternatives include erosion control blankets, soil tackifiers, or Sedum mats. | | *The lightweight material is more prone to wind erosion, and this should be accounted for in the initial design, alternatives include erosion control blankets, soil tackifiers, or Sedum mats. |
| |} | | |} |
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− | Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation <ref>MacIvor JS, Margolis L, Puncher CL, Carver Matthews BJ. Decoupling factors affecting plant diversity and cover on extensive green roofs. J Environ Manage. 2013;130:297-305. doi:10.1016/j.jenvman.2013.09.014.</ref>; stormwater retention was not improved with this increase in depth <ref name =Hill/>
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| [[category:materials]] | | [[category:materials]] |
− | [[category:infiltration]]
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| [[category:green infrastructure]] | | [[category:green infrastructure]] |