An eco roof, also called a green roof, is an environmentally friendly alternative to a conventional roof. A layer of soil is placed on the roof where vegetation is then planted. This adds insulation, reduces the amount of construction debris from shingles, and creates a more usable area out of the same space. Creating eco roofs can help reestablish ecosystems that were demolished during construction, particularly in urban areas.
Green roofs require a multilayered configuration, beginning with a waterproof membrane to prevent water from entering the house. A root barrier is placed on top of the waterproof membrane to stop roots from attaching themselves to the house. A drainage system is constructed, on top of which the soil layer is situated. This layer ranges from 4 to 6.5 inches (10.16 to 16.5 cm) in thickness. The final component of the eco roof is vegetation, which can include variations of local and exotic plant life.
Many people find that the extra space afforded by an eco roof is useful for creating their own garden. Some may choose to add aesthetic details to their house, while others enjoy the additional space for growing edible plants. Eco roofs also provide homes, businesses, and large buildings with better insulation compared to other roof types. Employing a green roof has been proven to significantly reduce energy expenses.
Water runoff is a problem in urban environments that can be prevented by installing a green roof. Sewer systems can overflow and release sewage into the streets following a heavy bout of rainfall. Green roofs can retain up to 75% of the rainfall that falls on them and absorb pollutants into the soil. The water stored in the soil eventually transpires and evaporates into the atmosphere, cleansed of many impurities.
Adding more green space to an urban environment can help reestablish former ecosystems that were lost during early urban development in the 19th and 20th centuries. During these times, the harmful effects of city construction and maintenance on the existing ecosystem were given little thought. Birds and insects were driven out or forced to survive in urban cityscapes, altering their natural behavior. Eco roofs provide extra living space for animals, restoring balance, and encouraging them to feed on their natural prey instead of human by-products or waste.
The influx of plant life into an urban environment helps reduce greenhouse gases, such as carbon dioxide. Cities produce great amounts of carbon dioxide in a very dense space, with little to no vegetation to recycle the gas into oxygen. Adding an eco roof on a major city building, regardless of height, allows plants to absorb carbon dioxide. As more roofs are converted, carbon dioxide levels decrease. The amount of harmful gas buildup in the upper atmosphere, which contributes to ozone deficiency and warming trends, is lowered.
There is very little concern about waste or hazardous by-products from green roofs, due to their organic nature. Conventional shingled roofs result in large amounts of waste from excess material or old shingles that are removed for re-roofing. In the United States, shingle waste accounts for up to 10% of construction and demolition waste in a year. An increase in eco roofs substantially cuts the amount of waste produced by the construction business.
The downside of eco roof conversion is the high initial cost. While a green roof has the potential to significantly lower costs within years after its implementation, installing one is more expensive than a traditional roof. Eco roofs, like others, have an upkeep cost. It is usually much lower than maintenance costs for shingle roofs, however, and its favorable attributes, such as added insulation, reduce expenses in the long run, canceling out the cost of upkeep.