Example of a simple extensive green roof Photo credit: International Sustainable Solutions  Flickr CC BY-NC 2.0

Trees and shrubs growing on roof top terraces of the LDS Assembly Hall and Conference Center in Salt Lake City, Utah  Photo credit: Abel Cheung Flickr CC BY-SA 2.0

Two basic types of green roofs are commonly constructed; extensive and intensive.

I. Extensive Green Roofs

PROS

• Uses shallow soil medium making it lighter weight
• Harsh conditions favor drought tolerant plants such as sedums
• Minimal maintenance
• Relatively low cost
• Pre-planted modules are available for ease of installation

CONS

• May require occasional maintenance such as weeding
• May require additional irrigation during extended dry periods

II. Intensive Green Roofs

PROS

• Uses deeper soil medium
• Can support trees
• Can use a large variety of plant types
• High wildlife habitat value

CONS

• Stronger roof structure is needed to support the weight so may not be appropriate for older buildings
• Tend to be more expensive
• Similar landscape maintenance to ground level landscapes
• May require additional irrigation

Additional Resources:

Green Roofs as Water-Wise Landscapes

Northeast

New Hampshire: Manchester's First Green Roof

Southeast

Florida: Green Roofs / Eco-roofs
Mississippi: Home Landscape in Mississippi

Browse related Articles by tag: water, green roofs, landscape sustainability, landscape water conservation