This project was carried out in the spring of 2012 on a canal barge which was moored on the River Thames near to Canary Wharf.
The client wanted to introduce a sense of nature and greenery to the deck of the barge, which was a permanent residence, but options for a garden were limited. He also wished to install the green roof himself.
A sedum green roof was suitable for such an installation as it was simple to install, would not require too much maintenance and be also lightweight. There were restricted height thresholds whenever the barge moved so it was not possible to consider large plants and shrubs. The low growing sedum plants were ideal.
The components of the sedum green roof system were delivered to site on a pallet. These included the protection and filtration fleeces and drainage membrane supplied on rolls; the aggregate substrate supplied in bags and the sedum blanket (reinforced with a polyester geogrid to hold the root structure together) rolled up loosely no longer than 24 hours previously.
Also supplied was a detailed instruction manual which stressed that the sedum blanket should be unrolled as soon as possible to avoid the lack of light and exposure of the roots damaging the plants.
The geotextile fabric was loose-laid into the deck. This would act as a protection layer to prevent point loading or any sharp objects from damaging the deck. It would also act as a filtration layer, stopping the drainage outlets form becoming blocked by particles or any discharge from the substrate stain staining the surrounding area.
The aggregate-based substrate was then spread out to a depth of 80-100mm.
This substrate is a special mix designed to be of course structure and free draining to encourage strong root growth, and to be low nutrient to support the sedum but not encourage grasses and wind-borne seeds.
A border of washed pebbles was created around the edge of the sedum to stop the roots of the plants clogging any vulnerable parts.
The sedum blankets were then gently rolled out onto the substrate and well watered in.
The change in appearance from a bare, stark deck was startling and the client was delighted with the results.
By the time summer came the sedum blanket was established into the substrate and bloomed into a most beautiful host of colours and textures.
It brought a beautiful and quite novel change to the appearance of the canal barge in the lock where it is moored. The client is delighted with the results and states that it has become quite a talking point for neighbours and passers by.