Difference between revisions of "Green roof media"

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<p>ASTM Interantional 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. </p>
 
<p>ASTM Interantional 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. </p>
 
Of particular note are:
 
Of particular note are:
<ul>
+
*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
<li>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 </li>
+
*E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms].
<li> E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms]. </li>
+
 
</ul>
 
 
<p>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 FLL guide [http://www.fll.de/shop/english-publications/green-roofing-guideline-2008-file-download.html] 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 high proportion of compost.[http://grit.daniels.utoronto.ca/wp-content/uploads/2016/06/Comparisons-of-extensive-green-roof-media-in-Southern-Ontario.pdf]</p>
 
<p>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 FLL guide [http://www.fll.de/shop/english-publications/green-roofing-guideline-2008-file-download.html] 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 high proportion of compost.[http://grit.daniels.utoronto.ca/wp-content/uploads/2016/06/Comparisons-of-extensive-green-roof-media-in-Southern-Ontario.pdf]</p>
  

Revision as of 13:49, 6 July 2017

ASTM Interantional 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:

  • E2399 Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems[1], and
  • E2396 Test Method for Saturated Water Permeability of GranularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. Drainage Media [2].

When these tests are completed, the results should be interpreted in relation to the objectives of the green roofA thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens.. A product complying with overseas guidelines may not serve the needs of a green roofA thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens. installed in Ontario. In particular, the FLL guide [3] recommends green roofA thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens. media specifications which may not provide optimal stormwater management or vegetation in our region. The green roofA thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens. 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 high proportion of compostDecayed organic material used as a plant fertilizer. Compost helps to support healthy plant growth through the slow release of nutrients and the retention of moisture in the soil..[4]

In many proprietary systems the default option for planting medium will be a granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. material with very low organic matter content. However, many companies can arrange for a high organic content alternative to be substituted if requested. The benefits of 'high organic' media are:

  1. Increased water holding capacity, which benefits both vegetation health and stormwater retention,
  2. Often lighter weight, even when saturated,

The disadvantages of a 'high organic' planting medium are:

  1. Increased phosphorous concentration in runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. water, however this may be mitigated by the reduced runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volume resulting in a lower loadingThe total mass of a pollutant entering a waterbody over a defined time period.The net amount of something (e.g. chemical, such as phosphorus), calculated as the product of concentration and volume in a given time. Some BMPs significantly reduce loading of pollutants to the environment by reducing volume more so than concentration. overall,
  2. The lightweight material is more prone to wind erosion(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc)., and this should be accounted for in the initial design, alternatives include erosion controlIncludes the protection of soil from dislocation by water, wind or other agents. blankets, soil tackifiers, or Sedum mats.

Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation[5]. Stormwater retention was not improved with this increase in depth[6].