Green Roofing Solutions

Mechanics

• The first layer of a green roof, the structural deck, gives the roof stability and prevents leakage into the building. The second layer, the waterproofing membrane, prevents the structural deck from taking on rain water and leaking. The third layer, the root barrier, stops plant roots from extending into the waterproofing membrane and causing damage. The fourth layer consists of several smaller layers of fibers, soil and drainage systems that allow the plants to grow. The last layer consists of plant life. Engineers use plants that can sustain high temperatures, heavy winds and droughts, such as grass and wildflowers, for easy maintenance.

Types

• Extensive roofs exist for the environmental benefits. They have layers of soil and come completely covered in plants to maximize the environmental benefits. Horticulturists at the University of Florida report that extensive roofs have a soil depth up to 7 inches and can support 15 pounds of weight per square foot. Intensive roofs, also known as rooftop gardens, allow access to the public. Intensive roofs have a mix of plants and walking trails, sitting areas or viewing areas. Intensive roofs require more maintenance than extensive roofs and must rest on a flat roof surface for safety.

Benefits

• Green roofs benefit both the structure and the environment. For the building, they provide lower utility costs as the green roof helps insulate the building. They can also absorb some of the environmental noise, making the inside of the building quieter. Environmentally speaking, a green roof helps add more plant life into urban areas. The addition of this green space helps air pollution as the plants can absorb toxins in the air. It improves water quality, and the roof will absorb rainwater and reduce run off from the building. Green roofs also become a natural habitat for birds and other wildlife.

Uses

• State governmental agencies have built green roofs on government buildings. For example, the University of Florida reports that the City of Chicago added a green roof to the top of city hall in 2001. Large corporations also install green roofs on their company buildings. The Ford Motor Company has a green roof expanding more than 10-acres on a plant in Michigan, according to horticulturists at the University of Florida. Private homes can also use green roofing technology. However, the homeowner should anticipate hefty building costs.