The drawings above show how to join new earthbag walls with old ones using buttresses. Put barbed wire between every course in the buttresses and through the rest of the structure. In the short-term, the buttresses strengthen the walls and serve as benches and plant stands.
Here is the two step building process:
1. Build buttresses at bench height (about 14”-18” high) where you want to add on (build another room) in the future. You can create stepped buttresses for aesthetics and added strength.
2. Pound in ½” rebar pins at an angle and possibly add some sheet metal anchors with long nails at an angle as you stack the new wall.
Related: Transforming Buttresses into Walls