Green Roofs are Changing Architecture and Planning

Green roofs offer benefits to a building owner and to the community. Before you decide that a green roof is right for you, it is important for you to understand the initial and long-term benefits, types, maintenance requirements, and costs of installing a green roof.

Modern green roofing projects have become enormously popular in European cities. In Germany alone, people have planted more than 108 million square feet of green roofs in recent years. It's estimated that 7 percent of all newly constructed flat roofs in Germany are green. In other parts of the world, people are catching on. In Japan, new construction projects in Tokyo require that 20 percent of the surface area of projects with over 10,000 square feet of roof be devoted to green spaces. In North America, cities such as Chicago and Toronto are defining themselves as leaders in promoting green roofing projects. The modern green roof is more than a combination and variety of plants. Modern technology has also expanded what we can grow on our roofs. You can find large scale green roofing projects on public buildings that include trees, vegetables, and ornamental gardens.

The two types of green roofs are Intensive and Extensive and the chart below is to help determine which type of Green Roofing Solution is suitable for your needs.

• Extensive green roofs: Much lighter than intensive green roofs. Soil depth is 1-6 inches and weight load 15 – 50 pounds per square foot.
• Intensive green roofs: Much heavier than extensive green roofs. Soil depth is typically 6-24 inches (or more) and weight load is 80-150 pounds per square foot.

Extensive Green Roof Semi-Intensive Green Roof Intensive Green Roof

Maintenance Low Periodically High

Irrigation No Periodically Regularly

Plant communities Moss-Sedum-Herbs and Grasses Grass-Herbs and Shrubs Lawn or Perennials, Shrubs and Trees

System build-up height 60 - 200 mm 120 - 250 mm 150 - 400 mm on underground garages > 1000 mm

Weight 60 - 150 kg/m2 13 -30 lb/sqft 120 - 200 kg/m2 25 - 40 lb/sqft 180 - 500 kg/m2 35 - 100 lb/sqft

Costs Low Middle High

Use Ecological protection layer Designed Green Roof Park like garden