THE LAYERS
1 - Waterproof Layer
The foundation of the green roof that protects against leakage.
2 - Root Barrier
The next layer protects against root damage.
3 - Drainage Layer
This layer sits atop the previous two and removes excess water from
the roof. This can be done using simple lightweight aggregates or preformed plastic cellular layers.
4 - Filter Fabric/Mat
A layer placed between the drainage layer and soil
to prevent clogging by the substrate.
5 - Growing Medium
This layer provides sustenance for plant growth.
It is usually composed of aggregate and organic materials that hold moisture.