The Silver Spray plan includes some flat roof areas that will have a “green roof”.
There were a wide variety of these at the Ecobuild show. It seems there are lot of options in terms of:
- What plants are in the green roof. All the way from tall grasses, shrubs to lower and thinner sedum matting.
- The base system that the green roof sits on and in. These range from egg cup looking sheets to matting that the plants grow into.
I asked Robert from ra-studio about his experience with green roofs:
I have done a couple, one in Cornwall (Sea house) and one on the Lancashire moors!
Green roofs are often used to combat heavy rainfall, and stop massive water run-off into the surface water sewers. With more and more people removing garden spaces (lawns etc) and replacing with hard paved terraces, the green roof system acts as a way holding the water back and allowing it to drain into the RW sewers far more slowly.
We used a Bauder roof at Sea House. Bauder do basically 2 types of green roof system – an intensive and extensive system.
The intensive system is a fully blown grass roof system that allows you plant lawn, shrubs, trees etc up there, and due to the thickness of the soil (normally a min of 250mm thick), it is quite a heavy build-up.
The extensive system is basically a sedum mat that is the thin / lightweight solution. It uses sedum / succulents in the form of a sedum mat (approx 25 – 30mm thick), and although the plants on the roof will take up some water it is far less that the full grass roof.
There is a drainage layer under the sedum mat, and any excess water that the plants don’t take up, is released into the drainage system. See Bauder’s website http://www.bauder.co.uk/green-roofs.
Under the green roof, there will still be thermal and water insulation. This a lot of other products were at the Ecobuild expo, “Stone Wood Slabs for a flat roof”.