A green roof, also called an eco-roof and garden roof, is a lightweight layered roofing system that allows maintenance-free plants to top a waterproofed substructure. Due to simpler technology, green roofs are not only becoming more common in residential areas, but in commercials areas as well, according to www.thisoldhouse.com.

Green roofs help to purify the air by absorbing pollutants and soaking up rain water, which reduces storm runoff that pollutes rivers and streams. They also keep a rooftop 10 to 20 degrees cooler in the summer and warmer in the winter, which lowers heating and air conditioning bills.

In some European countries, green roofs are mandatory for new commercial buildings. Even U.S. corporate companies, such as Target, Wal-Mart and Ford Motor Company have planted green roofs on some of their buildings.

While it might be possible to design your own green roof, it is recommended to hire an architect or landscape professional that has experience with eco-roofs. A good landscape professional will help design a green roof that contains plants for all seasons in your region.

Installing a green roof is more complicated than one would think, and involves several layers before the planting can take place. The bottom layer is usually made of plywood, steal or concrete. Then rubberized liquid asphalt is laid down, followed by a polypropylene root barrier, a drainage layer and a filter mesh fabric. The soil on a green roof consists of compost mixed with expanded shale, slate or fragments of volcano rock. Finally, your perennials can be planted.

Green roofs waste fewer fossil fuels and support a healthier environment. They can even provide a way to show off buildings' creative sides and personalities.