Extension of the lifetime of the roof; typical estimates are that a green roof potentially extends the lifetime of a roof between 200 and 300 percent, by protecting the rooftop from ultraviolet radiation, large temperature fluctuations, drying winds, and punctures.
Not only does the roof last longer, but there is reduced membrane maintenance. All this brings about significant cost savings over time. In some communities, storm water incentives may also bring substantial monetary benefits.