Green Roof Technology
- Lower weight: (17-30lbs/sf saturated) –often additional structural support is not required.
- Lower capital cost: $15-$30 per s.f.
- Depends on area, steepness, soil depth
- Relatively Shallow Depth: 1" to 5“
- Substrate: lightweight
- Low maintenance: inspection 1-2 times/year
- Supply of water and nutrients mainly by natural processes
- Native, natural plant selection (plants adapted to drought and heat and wind)
- Access: not designed for public use but can be accessed via walkways or for routine maintenance
- Increased weight: 30-100 lb per s.f.
- Increased capital cost: $30+ per s.f.
- Depth: usually 12” or more
- Substrate: higher amount of organic material in layers >100 mm
- Increased maintenance: depends on plant selection, e.g., mowing, fertilizing, watering, weeding
- Intense planting: manicured landscapes, ornamental lawns, flowers, shrubs, trees, even organic gardening
- Access: can be used as public park or building amenity
- Can include ponds, play areas, decks, patios, even a miniature golf course, etc.
- Often found over underground garages
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The extensive green roof at the GAP Office Building is viewed from a distance by building occupants, but also serves as an important habit for local wildlife including birds and butterflies.
An intensive green roof design for the courtyard in the Downtown Minneapolis City Hall sits above an underground parking garage.