Installation
Vegetation
Climatic conditions
To obtain a good result you must take account of the local weather conditions and you must adapt the vegetation to:
- wind direction
- possible dry periods
- possible periods of frost (with/without snow)
- possible air pollution
- exposure to the sun
- rainfall (period and intensity)
Green roof system
The choise defines the type of appropriate drainage, substrate layer and vegetation.
Plant selection
The selection of the plants depends on the green roof system chosen and the weather conditions in force. Local vegetation should preferably be chosen.
- Extensive: plants with limited requirements and good resistance to heat, wind and drought.
- Intensive: almost any plants in relation to the substrate type and thickness.
- A water irrigation system should certainly be provided for intensive planting.
Planting method
The choice of planting method is made in relation to the desired result and period.
Maintenance
Maintenance is limited to the following types :
- planting maintenance: up to one year after planting
- development maintenance : until complete coverage by the vegetation
- inspection maintenance : 1 to 2 times a year
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Safety
Fall protection
The safety guidelines in force must be complied with during the installation and maintenance. Fixed fencing on the roof edges or a harnessed system is consequently essential.
Access
The roof must be accessible safely
Fire Safety
Correctly executed and maintenance grren roofs can slow the spread of fire to and from the building. All roof penetrations/details must remain free from vegetation over a width of 500mm. A fire path, 1m wide and 300mm deep must be provided every 40m.
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Traditional roof structure of a green roof
Vegetation
Selection of plants in relation to the green roof system chosen
Substrate
- has the correct physical, chemical and biological components required for the growth of the chosen vegetation
- must have a certain level of stability
- must be sufficiently porous to ensure the correct water balance for the vegetation (water retention/drainage)
- must be sufficiently air permeable even in a fully saturated state
- must be lightweight
- must be suitable type and thickness in relation to the chosen vegetation
Filter layer
Protects the drainage layer from the “washin in” of fine sand particles and substrate particles that might result in a disruption to the water drainage.
Drainage layer
- ensures the drainage of superfluous water to the rainwater drains
- acts as a “reservoir”
- serves as the protective layer for the underlying root-resistant waterproofing
Protective/water retentive layer
- gives extra protection to the root-resistant waterproofing membrane which is especially recommended for intensive green roofs
- is suitable as a separating layer when the correct product is used
- retains water and nutrients
Waterproof and root-resistant membrane
Thermal insulation
- warm roof : under the waterproofing
- inverted roof : on the waterproofing
- suffieciently compression resistant for permanent load of the green roof
Vapour barrier
in relation to the insulation used and only on a warm roof
Roof structure
sufficient load-bearing capacity in relation to the expected permanent load
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