تويت
A green roof is built using a sequence of specialized layers that work together to protect the building and support vegetation. Each layer has a specific function, and the system performs best when all layers are properly installed. Below is a clear and easy explanation of every layer from the base to the top.
1. Roof Base (Structural Deck)
This is the main surface of the building.
It must be strong enough to carry the total weight of the green roof, including wet soil, plants, and retained water.
2. Waterproofing System
A sealed, durable membrane placed directly on the roof surface.
Its purpose is to prevent water from leaking into the building and protect the entire structure from moisture.
3. Root-Barrier Layer
A protective sheet that blocks plant roots from penetrating the waterproofing.
It ensures that roots grow upward and outward rather than down into the roof.
4. Protection Layer
This layer safeguards the waterproofing from damage during installation and maintenance.
It also helps distribute weight evenly across the roof.
5. Drainage Layer
A crucial layer that manages water flow.
It removes excess water, prevents flooding in the soil, and creates air pockets that keep roots healthy.
Some drainage systems also store small amounts of water for plant use.
6. Filter Layer (Geotextile Fabric)
A fabric layer that stops soil particles from entering the drainage layer.
It lets water pass while keeping the growing medium stable and clean.
7. Growing Medium
A lightweight engineered soil mix designed specifically for green roofs.
It holds moisture, provides nutrients, and supports plant roots without adding excessive weight.
This soil is very different from regular garden soil.
8. Plant or Vegetation Layer
The top living layer of the green roof.
Common plant choices include:
- Sedum plants
- Low-maintenance herbs
- Drought-resistant grasses
- Native groundcovers
These plants help cool the building, absorb rainwater, and improve the visual appeal.
Quick Summary
A standard green roof contains eight main layers:
- Structural Roof
- Waterproofing
- Root Barrier
- Protection Layer
- Drainage Layer
- Filter Layer
- Growing Medium
- Vegetation
Together, they form a complete system that is strong, efficient, and environmentally beneficial.
References :
Green Roof
Testing Waterproofing for a Green Roof
Understanding Green Roof System Layers