Clients often bring new challenges to the table, whether it’s a site located in a difficult climate, a unique twist like incorporating a wine cellar into a barn, or an interest in green technology and sustainable techniques. Recently, the latter came into play: a potential Blackburn greenbarns™ client liked our Hickory design, but wanted to add a tweak of his own in the form of a sod roof.
Admittedly, sod roofing hasn’t come up in my experience, but I am excited at the possibility of integrating this “new” old technology into the Hickory design. After surfing the web for sod roofing as well as discussing it with a member of my staff familiar with all things green, I thought I’d share what I learned with you. Consider this a crash course in sod.
A sod or a turf roof literally consists of the layer of ground that contains a mat of grass and its roots. According to Wikipedia, these roofs first appeared in Scandinavia, with a layer of sod set upon several layers of birch bark, which acts as a water sealant membrane. Modern sod roofs typically replace the traditional birch bark layer with other types of waterproof/root protective membranes.
There are various resources that provide instructional step-by-step and consulting information, such as this “How to Build a Sod Roof” article from eHow.com. A more professional resource is the Green Roofs for Healthy Cities (GRHC) association, which has a green roof certification program for professionals. The overall concept and application of a sod roof is simple—but that doesn’t mean it’s a DIY project.
One of the reasons you should consult a professional is to evaluate the structural loading capacity of the building intended for sod roofing. Since sod can be quite heavy—about 50 to 60 extra pounds per square foot over traditional roofing—it’s vital that the structure is capable of maintaining such weight. That’s why sod roof experts often indicate that the most suitable roof type has a low pitch. For this reason, the Hickory design our potential client is interested in would most likely require retooling in order to properly adjust to a potentially heavier roof.
Once the structural loading capacity is secure, there are many benefits to sod roofing. Here’s a short list:
- Excellent insulation and fireproofing
- Functions in a variety of climates except extreme
- Cooling in the summer and retains heat in the winter
- Wind and noise protection
- Long-lasting (up to 50 years is a frequently cited standard)
- Retains water to help prevent flooding
- Plants produce oxygen and reduce carbon dioxide
To elaborate upon the last item on the list, here’s a quote from James Nestor’s article, “Highly Sod After,” on Dwell Magazine’s Web site: “A single 16-square-foot roof of uncut grass produces the amount of oxygen that one person breathes in an entire year and removes up to 4.4 pounds of airborne pollution annually.”
Overall, sod roofing can be an effective way to “green” your roof and your lifestyle—a time-tested practice that proves sustainable technology isn’t always in the form of a fancy gadget or expensive material. What’s more accessible than your own backyard, after all?
Mother Earth News: http://www.motherearthnews.com/Green-Homes/1972-11-01/Sod-Roof.aspx
Dwell Magazine’s Web site: http://www.dwell.com/articles/highly-sod-after.html
Green Roofs for Healthy Cities (GRHC): http://www.greenroofs.org/index.php/about-green-roofs