Location: Europe
Project Type: Extensive Green Roof System
Main Products: Drainage Cell + HDPE Geomembrane + Long Filament Nonwoven Geotextile
Application: Green Roof Waterproofing Protection, Drainage & Water Management
Project Completion: 2025
Project Background
With the increasing demand for sustainable buildings and environmentally friendly urban development, green roof systems have become an important solution for improving energy efficiency, reducing stormwater runoff, and creating healthier urban environments.
A European construction company was developing an extensive green roof project for a commercial building. The project was designed to create a low-maintenance vegetation layer while providing long-term protection for the building structure.
However, during the initial design stage, the project team faced several technical challenges related to waterproofing protection, drainage efficiency, and long-term durability.
The local climate experiences frequent rainfall events throughout the year. Traditional drainage solutions used in previous projects had several limitations, including insufficient drainage capacity, water accumulation after heavy rain, and difficulty maintaining a stable moisture balance for vegetation.
The customer was particularly concerned about three key issues:
1. Excessive Water Accumulation After Heavy Rainfall
Without an efficient drainage layer, excessive rainwater could remain trapped inside the growing medium. Long-term water saturation could negatively affect plant roots, reduce oxygen availability, and cause vegetation decline.
The customer required a drainage system that could quickly remove excess water while still retaining a certain amount of moisture required for plant growth.
2. Protection of the Waterproofing Layer
The roof structure required reliable protection from mechanical damage during installation and future maintenance activities.
The waterproofing membrane is a critical component of the green roof system. Any damage caused by sharp aggregates, soil movement, or construction activities could lead to water leakage and expensive repair costs.
Therefore, the customer required a complete protection system combining waterproofing, separation, and drainage functions.
3. Long-Term Performance Under Outdoor Conditions
The drainage system needed to withstand long-term exposure to temperature changes, UV radiation during installation, plant root pressure, and continuous moisture conditions.
The customer required high-quality geosynthetic materials with stable physical properties and a service life compatible with the building structure.
Project Solution
After reviewing the project requirements, TINM recommended a complete green roof drainage solution consisting of three main layers:
HDPE Geomembrane Waterproofing Layer
Long Filament Nonwoven Geotextile Protection & Separation Layer
Drainage Cell
This integrated system was designed to provide waterproofing protection, efficient drainage, filtration, and long-term stability.
Products Supplied
1. Drainage Cell
Product: Drainage Cell
Material: (PP)
Height: 30 mm
Color: Black
Quantity Supplied: 8,000 m²
The Drainage Cell was installed above the waterproofing membrane to create a continuous drainage channel.
The three-dimensional cuspated structure provides:
High water flow capacity
Stable drainage performance
Protection of waterproofing membranes
Reduced hydrostatic pressure
Improved root environment
The drainage cells create an air and water flow space between layers, allowing excess rainwater to move efficiently toward the roof drainage outlets.
2. HDPE Geomembrane Waterproofing Layer
Product: Smooth HDPE Geomembrane
Material: Virgin HDPE
Thickness: 1.5 mm
Standard: ASTM D 5199 / GM13 Equivalent
Quantity Supplied: 8,000 m²
The HDPE geomembrane was installed as the primary waterproofing barrier.
Its main functions include:
Preventing water leakage into the building structure
Providing chemical and moisture resistance
Creating a durable waterproof foundation for the green roof system
The customer selected HDPE geomembrane because of its excellent durability, flexibility, and resistance to environmental conditions.
3. Long Filament Nonwoven Geotextile
Product: Polyester Long Filament Nonwoven Geotextile
Material: PET
Weight: 300 gsm
Width: 6 m
Quantity Supplied: 8,000 m²
The geotextile layer was installed between the drainage sheet and growing medium.
Its functions include:
Preventing soil particles from entering drainage channels
Maintaining continuous water flow
Improving system stability
Providing additional mechanical protection
The long filament structure provides excellent filtration performance and high puncture resistance, ensuring long-term reliability of the drainage system.
Installation Process
The complete green roof system was installed according to the project design requirements.
The installation sequence was:
Step 1:
The roof surface was cleaned and prepared before installation.
Step 2:
The HDPE geomembrane waterproofing layer was installed and welded to create a continuous waterproof barrier.
Step 3:
The Drainage Cell was placed above the geomembrane.
The interconnected drainage cells created a continuous water flow path across the entire roof area.
Step 4:
The long filament nonwoven geotextile was installed above the drainage layer to provide filtration and separation.
Step 5:
The growing medium and vegetation layer were installed to complete the extensive green roof system.
Project Results
After completion, the green roof system achieved significant improvements in water management and overall performance.
1. Improved Rainwater Management
The Drainage Cell System effectively collected and discharged excessive rainwater, preventing water accumulation inside the growing layer.
During heavy rainfall events, water could quickly flow through the drainage channels and reach designated outlets.
This improved drainage performance helped maintain a healthier growing environment.
2. Healthier Plant Growth
By maintaining an ideal balance between water retention and drainage, the system provided better conditions for plant roots.
The vegetation layer achieved:
Improved root oxygen supply
Reduced risk of waterlogging
More stable plant growth
Lower maintenance requirements
3. Enhanced Waterproofing Protection
The drainage sheet and geotextile layers provided additional protection for the HDPE geomembrane.
The complete system reduced the risk of mechanical damage and extended the service life of the waterproofing layer.
4. Long-Term Sustainable Performance
The completed green roof system successfully combined:
Waterproofing protection
Efficient drainage
Soil filtration
Vegetation support
The customer confirmed that the supplied products met the project requirements in terms of quality, installation convenience, and long-term performance.
The project provides a reliable example of how engineered drainage systems can support modern sustainable construction.
Final Project Summary
Project: European Extensive Green Roof System
Area: 8,000 m²
Products Supplied:
| Product | Specification | Quantity |
|---|---|---|
| Drainage Cell | HDPE, 25mm height | 8,000 m² |
| HDPE Geomembrane | 1.5mm smooth HDPE waterproof membrane | 8,000 m² |
| Long Filament Nonwoven Geotextile | PET 300gsm | 8,000 m² |
Achieved Results:
✓ Efficient stormwater drainage
✓ Improved vegetation growth
✓ Protected waterproofing membrane
✓ Reduced maintenance requirements
✓ Extended roof system service life