In order to ensure long-term functionality of a green roof the controlled discharge of surplus water is very important. In case the drainage and discharge of water do not function properly undesired vegetation transformations and unplanned additional load because of water accumulation is possible.
The basis for calculating the water discharge is explained in DIN EN 12056 Part 3. This is stated more precisely in DIN 1986 Part 100 in Germany. The application of these norms to the object specific characteristics is entirely possible using the Optigreen products and is also provable by calculation.