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.