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.

Drainage Types

Optigrün international AG offers different drainage types:

Drainage Boards made from plastic:

  1. Optigreen Drainage Board Type FKD 25 for single-layer extensive green roofs
  2. Optigreen Drainage Board Type FKD 40 for more sophisticated extensive green roofs
  3. Optigreen Drainage Board Type FKD 60 for intensive green roofs
  4. Optigreen Drainage Board Type FKD 10 or 12 for pathways and areas accessible by vehicles

Drainage Materials made from bulk material (expanded shale, expanded clay, lava):

  1. Optigreen Drainage Material Type Perl 2/10 for extensive green roofs
  2. Optigreen Drainage Material Type Perl 8/16 for intensive green roofs

Practical Applications

Optigreen offers a variety of different drainage solutions that suit every need and situation, especially situations which require special attention to drainage:

  1. For single-layer and zero-pitch roofs the Optigreen Drainage Board Type FKD is reccommended in order to prevent water accumulation.
  2. For pressurized drainage systems it is important to pay attention to a water accumulation free drainage which can be enabled using Drainage Board Type FKD and Inspection Chambers.
  3. For large roof areas or extremely long flow lengths Triangle Water Discharge Systems should be used in combination with Triangle Collection Flues. 


For more information and object specific calculations, please contact Tobias Klinger: 

Tel. +49 (0)7576-772-174
E-Mail: klinger[at]optigruen[dot]de