What Kind of Roof Would Be Suitable for a Rooftop Garden?
Theoretically, any roof surface can be greened – even sloped or curved roofs can support a layer of sod or wildflowers. Switzerland has just passed a bylaw which states that new buildings must be designed to relocate the green space covered by the building s footprint to their roofs – even existing buildings – including historical buildings – must now green 20% of their rooftops. This has created an increased demand for research and material/product design. There is a cable/tent structure over a school in Lyons, France which is covered with grass – the grass provided a refreshing green view from the urban classrooms as well as enough weight to eliminate some of the cables otherwise required to hold down the tent on windy days! The question is how to keep the soil from washing away while you re waiting for the plant roots to grow enough to hold the soil. Plants can grow in a medium of gravel – double duty for a layer of gravel ballast – easy, instant, and no additional weight. Rainwater
