Is a green roof right for you? By the way, I am not referring to the color of your shingles.
A green roof is a roof that is partially or completely covered with vegetation and soil (or other growing medium) that is planted over a waterproofing membrane.
In August I had the opportunity to see a green roof for the first time at McCrory Gardens in Brookings, SD. Enercept provided the roof panels for this straw bale structure, "The Children's Gardening & Outdoor Education Center" and we were invited to the dedication ceremony. I was not aware of their plans to install a green roof over our panels and was pleasantly surprised at this discovery.
Having never seen a green roof first hand I found it very interesting. They first installed a typical roof, with standard 3-tab shingles, then added a rubber membrane and installed the 4'x4' green roof packs on top of that. The soil is a gravel-type soil which, according to David Graper - head of the horticulture, forestry, landscape and parks department at South Dakota State University, takes about 2 1/2 inches of rain before it even drains. The plants used were a 'sedum' varienty which are drought resistant and hardy enough to survive South Dakota winters. Mr. Graper is also going to look at plants that are native to South Dakota to see if they will work.
There are many benefits to installing a green roof like the reduction of heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building, the reduction of stormwater run off, filtering pollutants and CO2 out of the air, and prividing an additional habitat for wildlife.
Other examples of green roofs can be found at the Ford Motor Company's River Rouge Plant in Dearborn, MI, Chicago's City Hall and Gap headquarters in San Bruno, CA.
Before you start your green roof project you'll want to make sure your existing roof can handle the weight load and keep in mind that maintenance costs could be higher.
For more information check out http://www.greenroofs.org/
