Perhaps of all the types of commercial roofs available today, green roofing systems have experienced the greatest surge in popularity in the last few years.
Green roofs are typically flat roofs that are partially or completely covered with vegetation soil and planted over a waterproofing membrane. This system reduces the heat island effect by absorbing heat and has been found to dramatically improve the roof’s insulating values. Green roofs lengthen the lifespan of the roof as much as two to three times, resulting in savings in heating and cooling costs as well as roof repairs and replacement.
The environmental impact of these buildings and their green roofs are increasingly important in today’s design and installation considerations.
Green roofs go beyond the meaning of contemporary architecture and give a new value to the role of buildings within urban planning. They are designed not only to bring back the natural element in the urban environment but also to provide solutions for important issues such as urban heat, island effect, and stormwater management.
GREEN ROOF TYPES
Extensive green roofs
Extensive green roofs have shallow (typically 7–10cm) soils. They support sedums, moss, herbs, grasses and other vegetation where low or no maintenance is required. They are the lightest type of green roof.
Extensive green roofs provide attractive protection to the waterproof
membrane and significantly reduce water run-off. When the green roof is completed, inspection once or twice per year shall be provided. Regular fertilization once per year, in fall or early spring, is required to ensure proper growth and success. The irrigation system is not needed unless there are extremely long periods of dry weather conditions. Regular access to the extensive green roof is not required.
Intensive green roofs
Intensive green roofs have a deeper soil layer (15cm upwards) and a wider variety of plant types can be grown, from lawns to ornamental bushes and semi-mature trees. The type of planting will determine the depth of soil required, the need for an irrigation system, and the level of maintenance. Regular roof access is normally provided on this type of green roof; therefore, paved areas, walls, and even water features are incorporated in the design.