Living Roof Drainage

The most critical role of the drainage layer is to provide an adequate flow of water off the roof during and after rainfall.

Living roof drainage.

Usually a roof slope of 40 degrees or more is required for runoff or else the living roof might end up in the home s living room. The drainage layer has an important role to play in the total system structure of a green roof. The design of the different drainage layers allows for a portion of the stormwater to be retained above where the water is allowed to flow freely off of the roof. Greengrid is most effective on flat roof surfaces maximum slope of 1 12 using the largest continuous roof area.

This website based guide builds on the material and information in our original pdf the diy guide to green living roofs which we published in 2008. The drains are usually placed near the center of the building. Residential homes may also have this type of commercial roof installed. Commonly used on flat commercial roofs siphonic drains allow for a minimal number of drains and all of the drains can be connected to a single leader.

Put large gravel or pebbles around the edge of the roof in the space you ve left this is to ensure drainage at the bottom and also stop the plants growing into the building 4. What is the best application for greengrid and or modular. Siphonic roof drain a siphonic roof drain utilizes siphoning as a drainage mechanism resulting in drainage that is faster than that on any other type of roof drain. When the retention cups are at capacity water drains through the raised drainage holes through the drainage channels.

The drainage also contributes to good aeration of the plant roots. It buffers water and allows excess water to drain away. Inner drains are found many times on large building roofs. During a dry period the water stored can be reabsorbed by the vegetation layer above.