| The second type of roof garden is green roofs in which the rooftop actually becomes the planting medium. This involves more intensive investments(upto two times the cost of a normal roof), but comes with its own set of advantages, including greater storm-water retention, building insulation, and the formation of patchwork urban ecosystems, which work to reverse the fragmentation of ecosystems that follows urbanization by offering temporary habitats to fauna such as birds and butterflies during their long migrations. Green roofs are constructed using a special root and water-proof membrane for the base layer, then a root barrier, a retention/drainage layer, plus the soil layer, and finally the plants. Alpine plants or desert succulents are often used for green roofs, as they can withstand harsh rooftop conditions like wind, erosion, and extreme temperature. Native plants are also used for rooftop plantings, though all of them are not conducive for roof top conditions. Herbs are commonly grown too as they need minimal soil depth. With a modular green roof system, roof infrastructure access and maintanence has become much easier as parts of the roof can be moved independently. | The second type of roof garden is green roofs in which the rooftop actually becomes the planting medium. In the early 1960’s green roof technology was developed in Switzerland and enhanced in many countries, particularly Germany. In the 1970’s, a significant amount of technical research was carried out on root repelling agents, waterproof membranes, drainage, and lightweight growing media and plants. By the year 1996, 10 million square meters of roofs in Germany had been covered with gardens. In European countries such as France, Germany and Austria, green roofs are viewed as an effective strategy for increasing green space in cities, reducing stormwater runoff and achieving other environmental benefits. A green roof involves more intensive investments(upto two times the cost of a normal roof), but comes with its own set of advantages, including greater storm-water retention, building insulation, and the formation of patchwork urban ecosystems, which work to reverse the fragmentation of ecosystems that follows urbanization by offering temporary habitats to fauna such as birds and butterflies during their long migrations. Green roofs are constructed using a special root and water-proof membrane for the base layer, then a root barrier, a retention/drainage layer, plus the soil layer, and finally the plants. Alpine plants or desert succulents are often used for green roofs, as they can withstand harsh rooftop conditions like wind, erosion, and extreme temperature. Native plants are also used for rooftop plantings, though all of them are not conducive for roof top conditions. Herbs are commonly grown too as they need minimal soil depth. With a modular green roof system, roof infrastructure access and maintanence has become much easier as parts of the roof can be moved independently. |
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