Types of Green Roofs
Green roofs are generally categorized as either intensive or extensive, depending on the depth of planting medium and the amount of maintenance they need.
Roof gardens which require a reasonable depth of soil to grow large plants or conventional lawns and are labour-intensive, require irrigation, feeding and other maintenance.
Typical use: Office buildings & Hotel Roofs
Typical medium depth for lawn: 15 to 35 cm
Example: Chicago City Hall
Designed to be virtually self-sustaining and require only a minimum of maintenance, perhaps a once-yearly weeding or an application of slow-release fertiliser to boost growth. They can be established on a very thin layer of “soil” (most use specially formulated composts). Even a thin layer of rockwool laid directly onto a watertight roof can support a planting of Sedumspecies and mosses.
Typical use: Household roofs which are generally inaccessible to public
Typical medium depth for moss-sedum: 2 to 6 cm
Example: Glengarda Children’s Centre