The environmental benefits of turf and green roofs are widely recognised, while roof gardens and roof terraces provide much-needed outdoor space in urban areas.
Due to the high degree of insulation that they provide, green roofs are known for their ability to provide an extremely constant temperature throughout the year. During the winter they keep the heat in, and in the summer they provide a relatively cool environment. Green roofs also have the ability to soften harsh edges of buildings in sensitive environments, making them blend in with the surrounding area.
Turf and green roofs provide habitat for insects and other wildlife. Where new buildings are built on greenfield sites, this new habitat can replace the habitat that would otherwise have been lost.
Green Roof Design Considerations
The most important considerations when designing turf and green roofs are ensuring that the roof is strong enough to support the weight of the turf or plants (even when they are fully saturated by rainfall and covered in several feet of snow!) and ensuring that the roof is watertight.
Structural calculations will need to be made, and the foundations and roofing timbers are likely to require upgrading in order to support the additional weight of a turf or green roof.
Types of Green Roof
Methods of construction differ between pitched green roofs and flat green roofs. Flat green roofs can be either extensive (have a thin layer of growing material such as sedum matting) or intensive (greater soil depth with shrubs and even trees). The weight requirements for intensive green roofs are such that they are normally installed over concrete roof decks.
A further type of green roof is known as a biodiverse or brown roof. These are constructed in a similar way to flat green roofs, but are designed with specific biodiversity objectives in mind – e.g. maximising biodiversity or providing a habitat for a specific species.