Green roofs are used for various reasons including: urban oasis, storm water mitigation, carbon reduction, energy conservation, aesthetics, and therapeutic values depending on the geographic location and the intended specific goals of the project.
[2] An improperly designed subtropical climate vegetated (SCV roof) using incorrect soil media and plant species can fail by not achieving the intended goals.
[2] This roofing method also contributes towards growing the green economy, clean energy technology policies, and qualifies for Federal and local tax incentives, set in place by the United States government.
Due to high temperatures, prolonged heat, and excessive amounts of precipitation, humid subtropical regions of the United States receive the greatest environmental benefits provided by SCV roofs, which are: reduced rainwater input into storm water retention systems during rainfall and increased energy performance ratings in buildings.
In other regions of the United States, the greatest environmental benefits of green roof design may be different based upon the type of climate the area possesses.
Recent advancements in soil engineering and plastic technologies allow vegetated roofs the ability to adapt to different locations within the humid, subtropical region of the United States.
[4] High density plastics permit SCV roof systems to withstand the weather elements and adjust to varying building types of the region.
An SCV roofs requires a unique soil media mixture to adapt to the harsh weather conditions and physical characteristics of the southern United States.
Perlite, vermiculite, ash, tire crumbs, sand, peat moss, and recycled vegetation are some of the other elements utilized in soil media engineering.
Current research suggests that the depth of the soil media, material, and number of layers affect the success rate of an individual green or SCV roof.
Plant species that have extensive root system and tend to be rangy can puncture waterproofing elements or grow into unwanted areas causing mold and mildew.
Mold and mildew can form on areas of the roof and building when proper ventilation is not taken into consideration and are also repercussions of high humidity levels and prolonged heat.
Soil media erosion and poor plant establishment are the most common problems and can occur on any angle of sloped roof if not designed properly.