learn about green roof drainage

Green Roof Drainage

Learn how to correctly drain a green roof

drainage on a green roof on a new house extension

New Builds

A step by step guide to creating a SAFE and LEAK FREE green roof on a new small scale construction project. Learn from the vastly experienced authors how to accomplish it yourself or provide guidance to your contractors

draining a retrofit green roof


Even the smallest of roof spaces can provide a small haven of beauty and a wildlife oasis. The retrofitting section advice can be used on garden sheds, cycle & bin shelters, the fundamentals remain the same!

edge drainage details on a garden shed green roof


From suggested screw sizes through edge details to drainage suggestions, John & Dusty take you through the process using text, photos, illustrations and videos

Green Roof Drainage – Allowing Rainfall To Escape

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.

Green Roof Rainwater Drainage utilising a Gabion Roof Edge

Making a gabion edge to help with rainwater drainage