Lack of water is one of the biggest stresses on a green roof. However too much water on a roof can cause a number of serious issues:
- Potentially overloading from the increased weight of water,
- Vegetation that does not like anaerobic conditions can be killed off by excess water.
How do you drain a green roof?
One of the main concerns that small scale builders have outlined to us is how to provide green roof drainage to adequately cope with rainfall of all quantities. The guide gives rational to the whys and hows of allowing good rainwater drainage. Before commercial drainage layers were developed, it was common practice to use a thin layer of gravel to act as a drainage layer. However gravel is relatively heavy. In the guide we explore innovative and creative ways of dealing with drainage as well adding to the visual landscape design and biodiversity of the roof.