Question: Green Roofs are new and becoming more popular and Sedum are touted as ideal plants for Extensive Green Roof systems. What is the difference between Extensive and Intensive Green Roof systems?
- Last revised:
- Tuesday, 22 December 2009
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Answer
A: Green Roofs are actually not a new phenomenon. Plants have been grown on rooftops since prehistoric times, but the modern incarnation really began to take off in Europe after in the early 20th century. Most of the research that we rely upon was conducted and published in the German language. Consequently when the terminology is translated it often seems counterintuitive to native English speakers.
Basically an Extensive system has less than 6” (15cm) of growing medium, while an Intensive system has at least a foot (30cm) and usually considerably more, with 4’ to 6’ (120cm-2m) not being uncommon.
Intensive systems typically require more intensive planting and maintenance. They are often more of a garden on a roof.
Extensive systems have a limited pallet of plants that are appropriate for the shallow medium depth and are more often used on roofs that are not necessarily accessible on a regular basis but require coverage to mitigate heat, contain storm water and protect roofing membranes.
Basically an Extensive system has less than 6” (15cm) of growing medium, while an Intensive system has at least a foot (30cm) and usually considerably more, with 4’ to 6’ (120cm-2m) not being uncommon.
Intensive systems typically require more intensive planting and maintenance. They are often more of a garden on a roof.
Extensive systems have a limited pallet of plants that are appropriate for the shallow medium depth and are more often used on roofs that are not necessarily accessible on a regular basis but require coverage to mitigate heat, contain storm water and protect roofing membranes.