A green roof may also be known as a grass, brown or biodiverse roof; but all of these terms essentially refer to a roof covered with vegetation. Green roofs are suitable for almost any type of building be it a house, office, garage or shed. This type of roofing is especially popular in Germany and Scandinavia and is slowly becoming more common in the UK.
“Green roofs would often happen by accident,” says Dusty Gedge, from the Green Roof Consultancy and Livingroofs.org. Speaking at 2011’s Ecobuild show, he explains: “The Germans covered their flammable flat roofs with sand to prevent fire, which then flourished into grass – this is essentially how modern green roofs came about.” There are two types of green roof:
Intensive green roofs
An intensive green roof is what many people would refer to as a roof garden. According to the Green Roof Centre (GRC), an intensive green roof has a layer of substrate at least 20cm thick which supports a range of trees, flowers, shrubs and vegetation. Depending on what types of plants you choose, an intensive roof will require regular maintenance, as with any garden. It’s important that the building is structurally able to take the additional weight of an intensive green roof.
Extensive green roofs
Extensive green roofs are a more popular option as they are easier to install, maintain and aren’t excessively heavy, so are suitable for more types of roof. The soil layer in an extensive green roof can be only a few centimetres thick and will support tough types of vegetation and shrubs which need little care once planted. To make installation even easier, an extensive roof layer can be rolled out onto the roof in a similar way that turf can be applied to a garden.
- Cool and insulate a building
- Provide sound insulation
- Save money on bills
- Provide fire resistance
- Reduce rainwater run-off
- Encourage wildlife
- Increase the lifespan of the roof
- Improve air quality