A green roof is essentially a layer of rooting material and plants over a traditional roofing system. Green roofs have been used for hundreds, if not thousands of years, from sod roofs in Europe to sod houses in the Great Plains of the United States. What have changed are the materials, designs and technology used in modern green roofs. Furthermore, a greater understanding of how green roofs function has expanded their use for stormwater management and building climate control.
Open image gallery of green roofs in Lincoln
Green roofs can vary in cost to install and maintain depending on the configuration. One type of green roof — an extensive roof — is a lightweight system of manufactured root medium with a light layer of plants. This type of system is more easily incorporated into conventional building construction and requires little maintenance. Another type — an intensive roof — typically uses a deep rooting medium such as topsoil, and can support a wider variety of plants, but is heavier and requires more maintenance. A green roof design may combine elements of both types to best suit each installation.
Depending on the type of green roof used, the level of benefit will vary, but nearly all configurations share some advantages.