courtesy of Frode Inge Helland

In Norway, the word for these roofs is "torvtak," literally translating to "turf roof."

How it works...

Traditional turf roofs, in Scandinavia, were made with layers of birch bark for waterproofing and two layers of sod. Contemporary living roofs have more components. A waterproof barrier is laid down over the roof, followed by insulation. On top of this is a layer that blocks roots from penetrating the roof, waterproofs, and also aids in drainage. The growing medium depends on the type of vegetation that is intended to grow, although many builders are opting for local soils and indigenous or naturalized plant species.

Living roofs can be intensive or extensive. In intensive system is constructed for larger plants, such as trees and shrubs that require a deeper growing bed. Extensive roofs are much shallower and are intended for the growth of grasses, wildflowers, and other plants with a shallow root system. The vegetation and soil provide a natural filter for rainwater and can be filtered into storm and grey water storage or irrigation systems.

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