A living roof is a roof which is covered in turf, flowers, grasses, and sometimes shrubs or trees. Living roofs have been used in home building in many parts of the world for thousands of years. A rising interest in sustainable or green architecture in the late 1990s led to a rising demand for living roofs on homes and offices. As a result, many cities around the world have stellar examples of living roofs, and their owners are often happy to provide tours.
There are many advantages to a living roof which an ordinary roof does not have. To begin with, a living roof provides an excellent layer of insulation which can help to keep buildings cooler in the summer and warmer in the winter. The roof also acts as a filter for rainfall, and improves drainage. The plants growing on the roof can provide habitat for animals, especially in an urban environment, and the living roof can also be pleasant to look at and walk on. Large areas of green space also help to improve the breathing, working, and living environment in urban locations.
Many alternative builders offer living roofs in their building plans. A sustainable and solid structure might be built from a material like cob and totally or partially turfed to blend into the landscape and benefit the environment. Companies concerned with their environmental performance also use living roofs on offices and factories. In a sense, the living roof could be considered an extension of the rooftop garden.
There are two primary divisions for living roofs. An intensive living roof has a deep substrate which can support trees and shrubs. This type of roof requires special reinforcement, because of the sometimes substantial weight. An extensive living roof has a much shallower substrate, and can be used to grow grasses, groundcover, and wildflowers. This type of living roof is cheaper and easier to install. Both types can be reconfigured just as a garden can, because the living roof covers a conventional waterproof roofing material, allowing roof gardeners to strip off chunks of sod from an extensive roof or dig into an intensive roof.
While many builders incorporate living roofs into new buildings, a living roof can also be installed on an older home. Homeowners interested in this option should consult with an experienced living roofing company. As is the case with any contractor, references should be obtained before agreeing on installation of a living roof, and the contractor should also be able to provide customers with a clearly written estimate sheet.