Want to get the low-down on something that could be above your head? Well here’s what you’ve been looking for: an introduction to green roofs!
There are two basic types of roof greening covers: intensive (roof gardens) and extensive. Intensive planted roofs have a greater depth of growing medium to support a wider range of planting, and often include shrubs and trees. Extensive roofs are systems with low growing plants, such as sedums, with no access other than for occasional maintenance; this type of roof is intended to be self sustaining.
There are three main methods of building up a green roof:
Inverted roof – has the insulation layer above the roof deck, on top of the waterproofing layer; usually constructed over a concrete roof deck.
Warm roof – has the insulation layer on top of the roof deck and the waterproofing layer on top of the insulation. In this system the insulation is always dry, giving a static thermal rating.
Cold roof – has the waterproofing membrane placed directly on top of the roof deck, with the insulation installed below the roof deck, or the roof may be uninsulated.
Green roofs are recognised as important in the delay of rainwater run-off entering the storm water system, and the general retention of rainwater. Other recognized environmental advantages of green roofs include:
Improved conservation and biodiversity.
Provision of new wildlife habitat.
Improved thermal insulation of buildings.
Reduction of airborne particulates.
Reduction in urban heat island effect.