What is a Green Roof?

A green roof is a roof that is either partially or completely covered by vegetation and a growing medium planted over a waterproof membrane. A green roof might include a root barrier as well as drainage and irrigation systems. A rooftop pond that is used to treat grey water might also be considered a green roof.

Green roofs can be installed on a wide variety of buildings including industrial facilities and private residences. A green roof can be as simple as a two-inch covering of drought resistant groundcover, or as complex as a fully accessible park. Green roofs are becoming extremely popular throughout the United States for their many environmental and personal benefits.

In addition to being aesthetically pleasing, green roofs have a number of advantages; they:

• Reduce heating and cooling costs
• Extend the life of the roof
• Reduce noise inside the home
• Filter storm water
• Prevent flooding
• Help to cool and clean the air
• Provide a natural habitat for birds, insects and small animals
• Raise the market value of a home or building

Although there are several different types of green roofs, the two main types are “extensive” and “intensive.” An extensive green roof is designed to be self-sustaining and requires very little maintenance. It is placed like a rug over an area of roof where people are not expected to walk. An intensive green roof requires a thicker growing medium, irrigation, feeding and other maintenance. Additionally, an intensive green roof requires more labor and expense to install. You could also need to rebuild and/or redesign your chimney.

Not every home is a good candidate for a green roof. They weigh considerably more than conventional roofing so your home must be able to support the additional weight of the soil after a rainstorm. A wet green roof can weigh approximately twenty pounds per square foot. In order to green roof your home, your roof must be relatively flat and unshaded by trees, some excavation could be required.

Installation of a green roof must be performed by a roofing professional. The costs involved with installation are typically higher than installation of a conventional roof. In addition, maintenance of an intensive green roof can be quite costly. Installing a green roof typically requires a building permit. However, many cities encourage residents to install green roofs by offering tax breaks or other advantages.