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18/05/2010
What is the difference between an intensive and an extensive green roof?
Q. 1 What is the difference between an intensive and an extensive green roof?
A. There are two types of roof, intensive and extensive. Intensive roofs are deep – typically the build up is between 450mm and 600mm deep – in order to accommodate the planting of trees and shrubs for a communal garden or to support a rooftop car parking area. Load bearing can be as much as 450kg per sq m.
Extensive roofs are lighter than intensive versions and are not suitable for communal use. There are three main types:Sedum Blanket, which can include flowers and grasses. Turf & Grass, which uses plant and grass species that grow no more than 30cm high (so no mowing demanded); and Brown or Rubble, which comprise of crushed bricks, concrete and soil.
These are either self-colonising or planted with native seeds and provide an ideal habitat for animals, insects and birds. Plug planting of specific “feature” plants can be added to any of the above extensive green roof types to add a splash of colour, contrast or seasonal variation.
In today’s crowded cities, the roof has got to work much harder! Already our own population, currently just over 60 million, is expected to reach 70 million by 2029 therefore the opportunity to provide amenity, biodiversity, improved air quality and even urban agriculture cannot be ignored. Intensive and extensive green roofs provide an effective means of satisfying these demands.
A. There are two types of roof, intensive and extensive. Intensive roofs are deep – typically the build up is between 450mm and 600mm deep – in order to accommodate the planting of trees and shrubs for a communal garden or to support a rooftop car parking area. Load bearing can be as much as 450kg per sq m.
Extensive roofs are lighter than intensive versions and are not suitable for communal use. There are three main types:Sedum Blanket, which can include flowers and grasses. Turf & Grass, which uses plant and grass species that grow no more than 30cm high (so no mowing demanded); and Brown or Rubble, which comprise of crushed bricks, concrete and soil.
These are either self-colonising or planted with native seeds and provide an ideal habitat for animals, insects and birds. Plug planting of specific “feature” plants can be added to any of the above extensive green roof types to add a splash of colour, contrast or seasonal variation.
In today’s crowded cities, the roof has got to work much harder! Already our own population, currently just over 60 million, is expected to reach 70 million by 2029 therefore the opportunity to provide amenity, biodiversity, improved air quality and even urban agriculture cannot be ignored. Intensive and extensive green roofs provide an effective means of satisfying these demands.
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