Green roofs are an example of source control. Source control measures deal with run-off at, or close to, the surface where rainfall lands. You may need to use additional sustainable drainage system (SUDS) components to control any overflow.
Advantages of green roofs
Green roofs have a layer of vegetation or patches of vegetation as part of the roof cover and can:
- reduce or eliminate run-off from roof areas
- extend the life of your roof
- add insulation to your building during the winter months
- cool your building during the summer by evaporation
- provide sound insulation
- reduce the heat island effect in cities
- provide a habitat for wildlife
You can use a variety of green roofs, including:
- intensive systems - deep soil capable of growing shrubs and even trees
- extensive systems - thin layer of vegetation, such as sedum mats
Disadvantages of green roofs
Green roofs add weight so you should consider them at the construction stage of a new build. For an existing building, an extensive system is recommended as it adds less weight, but you should always consult an engineer to make sure that the structure is safe.