A roof garden is any garden on the roof of a building. Besides the decorative benefit, roof plantings may provide food, temperature control, architectural enhancement, and recreational opportunities. Available gardening areas in cities are often seriously lacking, which is likely the key for many roof gardens. The garden may be on the roof of a building which takes care of its own water and waste. Hydroponics and other alternative methods can expand the possibilities of roof top gardening by reducing, for example, the need for soil or its tremendous weight. Plantings in containers are used extensively in roof top gardens.
A green roof typically consists of the following components: an insulation layer, a waterproof membrane to protect the building from leaks, a root barrier to prevent roots from penetrating the waterproof membrane; a drainage layer, usually made of lightweight gravel, clay, or plastic; a geotextile or filter mat that allows water to soak through but prevents erosion of fine soil particles. Green roofs improve air quality, conserve energy, reduce storm water runoff and help reduce the urban heat island effect. The garden's plants reflect heat, provide shade and help cool the surrounding air. The water draws heat as it evaporates, cooling the air in the process. Plants also filter the air, which improves air quality by using excess carbon dioxide to produce oxygen. The most cost-effective time to construct a rooftop garden is when the roof needs to be replaced or newly constructed. However, some types of green roofs can be installed on existing roofs. Prior to designing and constructing your rooftop garden, you must first determine if your roof can support the additional weight of soil and plants. A licensed structural engineer or architect must be hired to conduct a structural analysis. The structural capacity largely will dictate the type of rooftop garden that you can build. A key...
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