The sedum “green roof” covering to most of the flat roofs means that:

• There will be less rainwater run-off from the site. So less downhill drainage problems in the area.
• The property enhances and increases local bio-diversity.
• There is extra insulation to the building.
• The sedum plants protect the flat roof membrane from UV, thereby extending it’s life.

On top of the “rubber” is a layer that lets the water drain:

Over this is soil:

and the sedum that arrived on pallets:

At the edges of the building is a strip of pebbles. Sedum too close to the edges can get “wind burnt” and a perimeter drainage layer is needed to channel water to the drain pipes.