Photo courtesy of FoodShare Toronto

An extensive rooftop makes use of a lightweight and shallow planting medium along with thin layers of drainage and waterproofing materials and shallow-rooted plants. Intensive rooftops may include trees, shrubs, vegetables, or other container plants and are more accessible to people.

Why are rooftop gardens important to birds and the environment?

Urban and suburban landscapes are dominated by impervious surfaces such as paved streets, sidewalks, parking lots, and buildings, which don't absorb rainwater. The absence of green space creates an urban heat island effect, where pavement and buildings make the city hotter than surrounding vegetated areas, thus increasing the energy needed to cool building interiors. Also, runoff from rooftops can cause flooding and pollute nearby waterways.

The installation of rooftop gardens and green roofs can save energy costs by reducing cooling needs and by reducing heat gains in summer and heat loss in winter. They can also protect water quality and provide habitat for birds. Rooftop gardens and green roofs can provide birds with nesting opportunities (both natural and manmade), food (seeds, fruits, and insects), and protective cover, bringing life to once desolate rooftops. They can also provide temporary havens for migrating birds and increase the diversity of common birds already adapted to human-influenced landscapes.

The installation of a green roof is a job for specialists, requiring structural analysis and professional design, including choice of plants appropriate for the conditions. A green roof can be considered on both commercial and residential buildings and either to replace an existing roof or as a new construction.

Getting Started: What You Can Do

• Visit the websites noted below to learn more about green roof options and the variety of environmental and human benefits.
• Share with building management examples of successful green roofs, preferably in your community.
• Build a coalition to create and maintain a rooftop garden. Explore funding opportunities and talk to contractors who specialize in rooftop gardens and green roofs.
• When designing a rooftop garden, create habitat targeted to birds in your area.

Helpful Links

• Green Roofs for Healthy Cities
  
• Greening Gotham
  
• Penn State Center for Green Roof Research
  
• U.S. Green Building Council: LEED
  
• Benefits of Green Roofs