We have been drawing up plans for our house for years, but putting a sod roof on our house is a new idea to me. My architects (Whole Tree Architecture) are comfortable with sod roofs. They have made several houses with a sod roof. Their studio has one. I have a steep learning curve to go up yet. I totally buy into the idea that a sod roof is right for our project and about as green as a roof can get. I think we will be seeing more and more living roofs because they make a lot of sense, once one gets past some misconceptions.
Greenroof Infrastructure Industry Association says there are already more than 300 accredited Green Roof Professionals (GRPs) since they began giving green roof exams in Atlanta in June of 2009, and they project more than 600 accredited GRPs by the end of 2011. These builders are mostly doing the large-scale, high-tech installations that will certainly green up cityscapes.
I’m more interested in the small-scale, do-it-yourself kind of projects, and these are picking up speed too. Living, sod roofs are a natural in many applications.
According to GREEN ROOF MANUAL: How to Replace your Dead Roof with a Living Landscape , the average green roof lasts for an average of 40 years as opposed to the 17-year life expectancy of roofs installed with standard roofing materials. That standard roofing tends to be asphalt shingles. Asphalt has become ubiquitous in our lives. We drive and park on it. We live under it. But it is petroleum based and energy-intensive to produce, and according to the National Association of Home Builders Research Center, roof installation generates an estimated 7 to 10 million tons of shingle tear-off waste and installation scrap.
More than 60 manufacturing plants across the U.S. generate another750,000 to 1 million tons of manufacturing shingle scrap every year. Though there is a movement to try to recycle old shingles, most of it is just one more disposal problem added to a long list.
We put a metal roof on our barn, which will last longer and make a wonderful surface from which to fill the cisterns we plan to put in this summer. But our house roof looks like it will be both too shallow in slope and too irregularly curved to work well with a metal roof. The reason is that the whole tree, un-milled rafters will inevitably have some naturally pleasing irregularities, yet they will be plenty strong to handle a shallow pitch.
There is a great article on putting on a sod roof in a recent Mother Earth News. They note that the beams and rafters under a sod roof will have to carry 100 pounds per square foot. This is twice as much weight as is supported by the corresponding beams and rafters under an ordinary roof. But it will work well with our timber frame construction.
Check out this cool website post about putting a sod roof on a cob house.
Categories: Eco architecture