Green Roof Types
A green roof is simply a roof covered with a layer of growing substrate and plant species.
There are two main types of green roofs: Extensive greening systems and Intensive greening systems. The choice of one or the other will depend on the type of vegetation needed, the function of the building, the amount of space available and the degree of maintenance required:.
FertilRoof systems allow the landscaper to choose either type depending on the structure of the building (load resistance), its intended use and the available budget.
Intensive systems
Intensive systems are green roofs where you can create spaces very similar to a traditional garden. The roof becomes a usable space and can host herbaceous plants, shrubs and in some cases even small trees. As well as recreational, the function of the roof is ecological, as it creates a a green surface area equal to the surface area of the building. .
This type of green roof requires considerable layers of substrate and therefore requires buildings to be able to support heavy loads equal to three or four times the average snow load.
These roofs need maintenance similar to conventional gardens, and irrigation.
| TYPE OF GREENING | Light with Sedum spp. |
| STRUCTURAL STRENGTH OF THE BUILDING | 90 - 150 kg m-2 |
| RUNOFF COEFFICIENT | > 0,7 |
| NOTES | Minimal maintenance. Possible combination with solar and electrovoltaic panels |
| TYPE OF GREENING | Light with Sedum spp. Or perennial plants |
| STRUCTURAL STRENGTH OF THE BUILDING | 150 - 250 kg m-2 |
| RUNOFF COEFFICIENT | 0,5 - 0,7 |
| NOTES | Minimal maintenance. Possible combination with solar and electrovoltaic panels |
| TYPE OF GREENING | Light with Sedum spp. Or perennial plants |
| STRUCTURAL STRENGTH OF THE BUILDING | 150 - 250 kg m-2 |
| RUNOFF COEFFICIENT | 0,5 - 0,7 |
| NOTES | Minimal maintenance. Possible combination with solar and electrovoltaic panels |
Extensive systems
Extensive systems are roofs built mainly with an ecological function in mind, to improve living comfort, and are rarely usable spaces. Nowadays, they often host a solar, thermal or electro voltaic system which improves efficiency.
Extensive systems are built with prostrate or creeping plants, suitable for growing in thin layers of substrate.
The load on the building is reduced and suitable for almost all building types.
Maintenance is reduced and irrigation is optional (to be evaluated in particular climate zones).
| TYPE OF GREENING | Semi intensive with turf. Intensive with perennials, trees and shrubs. |
| STRUCTURAL STRENGTH OF THE BUILDING | 250 - 350 kg m-2 |
| RUNOFF COEFFICIENT | 0,3 - 0,5 |
| NOTES | High ecological interest with abundance of species. Possible fruition |
| TYPE OF GREENING | Semi intensive with turf. Intensive with perennials, trees and shrubs. |
| STRUCTURAL STRENGTH OF THE BUILDING | 250 - 350 kg m-2 |
| RUNOFF COEFFICIENT | 0,3 - 0,5 |
| NOTES | High ecological interest with abundance of species. Possible fruition |
The basic construction scheme is similar for both types.
Depending on the type installed, the technical characteristics, dimensions and weights of the individual components can vary.
The choice of an intensive or extensive green roof depends on a series of design factors to be carefully evaluated:
- Structural strength of the building and climate of the area (rainfall, wind, etc.);
- Roof inclination (the ideal setting is a flat roof. For slopes> 5 ° it is necessary to adopt particular technical solutions;
- Type and size of the drains (the drains must be accessible for checks and properly sized);
- Type of roof waterproofing;
- Presence of energy devices (solar panels, electro voltaic, etc.);
- Available Budget.