As I mentioned in an earlier post, flat green roofs aren't just for commercial buildings, they are for homes also! While there are companies and architects and engineers willing to set you up with a very beautiful, but expensive, flat green roof, This Old House has an article.
This Old House used a product called GreenGrid, which has been available to pros, and is now available to regular folks. While this sounds wonderful, there is a catch (isn't there always?)"...no arid climes, tar roofs , or slopes sharper than 15 percent. $10-$15 a square foot..."
What is good to know, is that green roofs are starting to catch on. Now even the average home owner can put one on!