Green Roofs and Green Walls

A green roof (or living roof) is a roof that has plants growing on it. For centuries people have grown plants on their roofs to keep their buildings cool during the summer and warm during winter. These days green roofs still have the same benefits but also add much needed green spaces to urban concrete areas, replace habitats that have been lost due to developments and reduce demand on sewers by retaining approximately 70% of rain water that falls on them.(Picture www.greenroof.org.uk)

 

In general there are three types of green roofs:

 

This type of green roof consists of a deep layer of soil planted with various types of plants, shrubs and even trees. This type of green roof can be used as an amenity e.g. a park or nature reserve. They require regular maintenance, similar to a garden, and place a considerable amount of weight on the roof.

 

This type of green roof consists of a shallow layer of growing material normally planted with a sedum mat. It is suitable for a roof that cannot take much weight

And is not suitable as an amenity. It will retain water runoff and provide a habitat for creatures to live in. They require very little maintenance.

 

This type of green roof consists of a slightly deeper layer of growing material that Extensive roofs, which aids the growing of different varieties of plants. They have all the benefits of the other types of green roofs but cannot be used as an amenity.

 

The benefits of green roofs can be broken down into three groups:

 

 

 

 

Flat roofs are the most suitable to have a green roof. It is also possible to put a green roof on other types of roofs such as pitched, barrel and domed roofs. However, restraints are needed to ensure that the growing medium does not slide off. Roofs with very steep slopes are not suitable.

 

For a domestic property examples of roofs that could house a green roof are:

 

A leaflet showing how to do a DIY Green Roof is attached below. Also attached is an English Nature booklet about Green Roofs.

 

Although it is often thought that climbing plants can damage wall surfaces, in most cases if the wall is solid and well-built there is no reason why damage should occur. Care should be taken, however, in respect of walls with cavities or with crumbling mortar in which roots could take hold and expand.

 

Green walls not only help reduce the heat island effect, they also reduce external noise pollution entering a building and provide an important habitat for insects and other creatures.

For more information on green roofs and green walls visit www.livingroofs.org

 

 

If you would like any further information please ring the Sustainable Housing & Affordable Warmth (SHAW) team on 0114 273 5837. You can also email the team on shawteam@sheffield.gov.uk.