Green roofs can replace or replicate habitats that have been lost or are in decline.
New habitats can be created that improve biodiversity generally or specifically for a certain species. For example; creating habitats for ground nesting birds or providing a habitat for seed bearing plants for sparrows. The source of these drivers can be Local Biodiversity Action Plans (LBAPs) or national targets.
In addition, biodiverse roofs can offer sustainable drainage, countering the heat island affect, enhance the visual amenity and well-being of occupants and offer indirect financial benefit i.e. extending the life of the waterproofing. These roofs are not designed to be trafficked and can be installed on flat to shallow pitched roofs.
Planting and Waterproofing
Typically, the substrate is mounded to offer localised habitat variation across the roof, the depth of the biodiverse roof could vary between 92-170mm and have a saturated weight of approx. 115-215kg per sqm, depending upon the depths of the substrate.
A wider variety of succulents, grasses, herbaceous perennials, wildflowers, alpines and bulbs - these are typically offered as plug plants or pre-determined seed mixes.
Installation and Maintenance
Blackdown's systems can be installed either by their installation teams or by Alumasc's nationwide network of Registered Contractors.
Certain procedures are recommended to ensure the long-term success of the plants.
Typical procedures carried during maintenance include:
- Removal of unwanted plant material i.e. invasive species (if required)
- Correction of any localised plant system problems that may have occurred post installation
- Replacement of any failed plants
- Application of nutrient source
- Removal of dead flower heads (if required)
- Inspection of rainwater outlet chambers and surrounding vegetation breaks
- Replenishment of any areas of settled substrate
As a general guide, it is recommended that maintenance be carried out two or three times in the first year and once or twice in each subsequent year but this depends on the type of system installed and the rate of plant cover.
Temporary irrigation is required for a period of 6-8 weeks until the plant material is established, once it has reached this point no additional irrigation should be required.