Green Roofs

Until recently, 'green roofs' - a vegetative layer placed on top of an existing or new roof - were not considered part of a SUDS package but today that view is changing, with an increasing recognition of the part that natural vegetation and such roofs - or 'sky gardens' - can, and should, play in SUDS planning.

There are four requirements for a green roof: light, water, compost and drainage. A green roof can store up to 60% of rainwater, helping to prevent local flood risk. In addition, water is slowly released back into the atmosphere, CO² is reduced and a wildlife habitat is created.

Benefits of Green Roofs

• High water retention
• Run-off attenuation reduces sewer overflows

Improves environment

• Creates a beneficial monoclimate by cooling and humidifying the surrounding air.
• Absorbs greenhouse gases.
• Absorbs air pollution and dust.
• Reduces the heat island effect, which is the main cause of ozone production.
• Habitat for animals and plants.

Building fabric

• Protects the roof from mechanical damage and ultra violet radiation - thus extending the roof life.
• Can provide extra insulation
• Reduces noise levels

Can use recycled materials

• Many of the materials used in green roof construction are manufactured from recycled building materials, plastics and rubber reducing landfill disposal.

There are 2 types of green roof:

Extensive
A lightweight covering, with sedum providing a low-maintenance mono-culture.

Intensive
A load-bearing application with a variety of plant species.