Green roof media
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:
- E2399 Standard Test Method for Maximum Media Density for Dead Load Analysis of Vegetative (Green) Roof Systems, and
- E2396 Test Method for Saturated Water Permeability of Granular Drainage Media .
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 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.
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.
- 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.
- 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.