Biodiverse Green Roofs

Extensive green roofs designed specifically to create habitats for plants and animals can be termed Biodiverse (or Brown) roofs. These types of roofs are becoming increasingly specified in urban areas in order to recreate habitat lost by the development.

As the name suggests Biodiverse roofs are created primarily for biodiversity purposes and can aim to recreate the habitat that was lost when the building was erected, or even enhance it.

A ‘Green’ biodiverse roof would generally be broadcast with an appropriate seed mix (often wildflowers and grasses), and/or planted with species of plug plants (often wildflowers, sedums and grasses) to encourage specific plant types that will support certain bird and invertebrate species. Pre-grown mats containing mixes of drought tolerant wildflowers, grasses and herbs can also be installed to provide a more “instant” cover.

This category includes the ‘Brown’ biodiverse roof or “Brown Roof” which is not purposefully planted. The growing medium is selected and installed to allow indigenous plant species to inhabit the roof over time.

Substrate depths may vary across the roof deck to promote a diversity of both shallow and deep rooted plants and ones which are more and less drought tolerant. Undulating substrate depths also create differing habitats for a greater range of invertebrate species. Pebbles, boulders, gravels, sands, branches and logs may also be placed within the system to offer suitable habitats.

The “management” of a biodiverse type green roof very much depends upon what the client requires. It can be managed more heavily to produce a controlled “wildflower meadow” type environment. Less management input may lead to the development of vegetation which progresses naturally relating to the prevailing conditions.