The structure below the sheet must always include waterproofing and root barrier provided by, for example, Kerabit modified bitumen membranes with a layer of Kerabit Root Prevention Membrane on top. In inverted structures, Kerabit GreenDrain 40 is installed on top of thermal insulation, such as XPS.
The sheets are installed with one overlapping row of chambers so that the drainage outlets remain in line with the direction of water flow (at an angle to the direction of the slope) with the bottoms of the studs down. A filter fabric, e.g. N2/KL2, is installed on top of the sheet as a separation and filtering layer. If necessary, a protective layer or filter fabric is also installed below the sheet to protect the waterproofing or thermal insulation in case of inverted structures.
Installation should be carried out in calm weather to allow safe lifting of the materials without lighter materials being blown down the roof by the wind. The sheets should be covered with filter fabric and substrate as soon as possible.