Green roofs reduce the temperature of the building and the surrounding air in multiple ways.
Green roof slab thickness.
For roof gardens an extra load of 400 750 kg m2on the structure of the building must be accounted for compared to the 60 250 kg m2 of the extensive green roof.
Intensive roofs which are thicker with a minimum depth of 12 8 cm 5 1 16 in and can support a wider variety of plants but are heavier and require more maintenance and extensive roofs which are shallow ranging in depth from 2 cm 13 16 in to 12 7 cm 5 in lighter than intensive green roofs and require minimal maintenance.
It is common practice to use the term extensive to describe green roofs that are very thin and will only support hardy drought resistant vegetation such as sedums herbs and perennials.
Intensive green roofs have a higher weight and require a minimum soil thickness of at least 30 cm compared to the 5 12 cm of the latter.
The nominal thickness of a green roof is the approximate total height of the soil and drainage components that constitute the green roof system excluding the roof structure insulation waterproofing and plants.
The entire thickness of the layer is usually between than 6 to 15 cm.
Intensive to describe green roofs that are thick enough.
There are two types of green roof.
The plants in a green roof absorb water through their roots and then use surrounding heat from the air to evaporate the water while some roofs can reach temperatures of up to 90 f in the summertime these two features can allow.
Extensive green roofs are principally created for their ecological advantages.