Green Roof Types

Extensive green roofs

Extensive green roofs have shallow (typically 7–10cm) soils. They support sedums, moss, herbs and grasses and other vegetation where low or no maintenance is required. They are the lightest type of green roof. Extensive green roofs provide attractive protection to the waterproof membrane and significantly reduce water run-off. When the green roof is completed inspection once or twice per year shall be provided. Regular fertilisation once per year, in fall or early spring, is required to ensure proper growth and success.The irrigation system is not needed, unless there are extremely long periods of dry weather conditions. Regular access to the extensive green roof is not required. 


Intensive green roofs 

Intensive green roofs have a deeper soil layer (15cm upwards) and a wider variety of plant types can be grown, from lawns to ornamental bushes and semi mature trees. The type of planting will determine the depth of soil required, the need for an irrigation system and the level of maintenance. Regular roof access is normally provided on this type of green roof, therefore paved areas, walls and even water features are incorporated in the design.


Variables Extensive Intensive
Vegetation Sedum, grass, herbs Grass, ornamental bushes, trees
Height <15cm 25-100cm
Irrigation Mostly not Always necessary
Weight 50-150kg/m² 250-1,000kg/m²
Walking possibility No/Limited Yes
Water buffer 4-12mm 18-39mm
Load capacity roof Most normally sufficient Requires extra strong roof structure
Maintenance Very low Comparable with a normal garden
Roof pitch Up to 45° Flat or in terraces