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.

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.

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.