Bio-diverse systems ("brown roofs")

To some extent all green and brown roofs encourage biodiversity as they provide a habitat that supports various flora and fauna that would be unable to survive on a conventional rooftop. The basic aim of a biodiverse roof is to replace the ecosystem lost at ground level due to building construction, at roof level.

They are designed to meet specific objectives which include:

• Compliance with the local authority biodiversity masterplan
• Providing habitats for rare or threatened species such as the Black Redstart bird in the London area
• The project builders desire that the building operations will have a minimum negative, and even a positive, impact on the local environment
• Improving the aesthetic value of rooftops by ensuring that they intergrate with the surrounding landscape
• The utilization of recycled broken bricks which would otherwise be disposed of in landfill site

BROWN ROOF MAKE-UP

Drainage Layer:

• roof protection
• drainage facilitation
• water reservoir
• root barrier
• filtration fleece

Substrate:

Consists of a layer of locally sourced rubble / crushed brick overlaid by a root zone of subsoil and topsoil attained by removal during ground works at the initial stages of building . This ensures the utilization of materials that would have been transported elsewhere as well as reducing the volume of in – bound materials. This reduces the carbon footprint of the project and reduces the environmental impact.

Flora and Fauna:

Biodiverse systems by their nature encourage colonization by locally specific varieties of plants and animals . Population census of brown and green roofs have yielded the presence of large numbers of invertebrates, some rare and even endangered, such as insects, arachnids and various types of worms. In the London area the emphasis has been on the regeneration of numbers of the Black Redstart bird which is known to thrive on building rubble which it uses for nesting sites. Some brown roofs may be sown with different mixtures of area specific plants such as:

• wildflower mixes
• heathland plants
• various grassland mixes
• herbs etc.