From the earliest conception of our garden wall, we dreamed of topping it with a green roof. However until we actually started building the roof we had no idea how we were going to go about it. We first needed some sort of truss system since we wanted the roof to provide a protective eave for the wall. Again, we turned to Sketchup to model the dimensions of these trusses and settled on a pitch of 4 in 12 and a horizontal eve span of roughly 6 1/2″. We built the trusses out of dunnage from the lumber yard garbage bin, a GREAT source for scrap 2x4s, and fitted them along the top of the wall, tacking them in to place with blobs of cob. We did our best to tilt each one to rest roughly 90 degrees to the tangent of the curve at each point.
To give our wall a little curb appeal from the barn road and to get experience plumbing in cob structures we decided to incorporate a water feature in to the T junction buttress. Conveniently, around this time, the barn was getting a spring clean and an old porcelain sink was pulled out and left for the taking. We took it!
Early in the cobbing phase of building our wall, we decided to incorporate a fireplace in to it. We had so much fun building our first fireplace, and enjoyed using it so much, that this seemed like a perfect fit for our wall build. We placed it midspan on the soft curved wall, facing the original fireplace which allows us to have double fire place nights when our friends come over.
We started laying on the cob to our wall in March 2014. The earth for this project came from a construction site just down the road. It was a beautiful mishmash of grey clay, grit, and stones and required only the addition of straw and water to get a good consistency for cobbing.
In the summer of 2013 we built a cob outdoor fireplace. As soon as it was first fired, it became an instant gathering site and the large manure pile immediately behind it that collected from our barn of 7 horses became an increasingly troublesome eyesore (a shortcoming we had somehow overlooked in the fervid planning of the fireplace construction). We use the manure extensively on our property, to fertilize our pastures, build our hugelkultur gardens, and fertilize our berry patches and flower beds so getting rid of it was not an option. The solution to this problem obviously entailed another cob structure, and so was born the idea of the cob garden wall.