Changes

<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>

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:

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

*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

*E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms].

*E2396 Test Method for Saturated Water Permeability of Granular Drainage Media [https://www.astm.org/Standards/E2396.htms].

<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>

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>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 content 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 content alternative to be substituted if requested.   

The benefits of 'high organic' media are:

The benefits of 'high organic' media are:

#Increased water holding capacity, which benefits both vegetation health and stormwater retention,

<li>Increased water holding capacity, which benefits both vegetation health and stormwater retention, </li>

#Often lighter weight, even when saturated.

<li>Often lighter weight, even when saturated, </li>

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

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

#Increased [[Water Quality#Phosphorous|phosphorous]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall,

<li> Increased [[Water Quality#Phosphorous|phosphorous]] concentration in runoff water, however this may be mitigated by the reduced runoff volume resulting in a lower loading overall,</li>

#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.  

<li>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. </li>

Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation[http://www.sciencedirect.com/science/article/pii/S0301479713006051]. Stormwater retention was not improved with this increase in depth[http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001534].

Increasing the depth of planting medium from 10 cm to 15 cm has been shown to benefit the vegetation[http://www.sciencedirect.com/science/article/pii/S0301479713006051]. Stormwater retention was not improved with this increase in depth[http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001534]. </p>

 

 

[[category:materials]]

[[category:materials]]