All dry stone walls should be constructed with the thickness equal to one half of the overall height walls should be built leaning back toward the slope about 2 inches per foot of height for stability see fig 3 for walls that exceed 2 1 2 feet in height the use of bonding stones and a drainage system are necessary for long term stability bonding stones stabilize a wall and connect it to the slope that is being retained drainage behind any retaining wall of size is critical . How to build a dry stack stone retaining wall step 1 prepare to build your retaining wall proper planning makes most diy projects much easier and building a stone step 2 ensure proper drainage low retaining walls such as dry stack stone walls generally drain well with just a bit step 3 . Continue using the shovel to dig out the base for the wall this should resemble a narrow trench with the width matching the width of the base rocks the depth of the base should be approximately 1 2 times the width of the stone being used to build the dry stacked rock wall use a level to make sure the base is level and a measuring tape to make sure that the width of the base will accommodate the rocks being used for the first layer. 1 plan your project decide how wide and long youd like your rock wall to be and make sure that this is feasible with the location of your wall dry stacked rock walls are typically built against a hillside as it can be used as a tool to prevent soil erosion from ruining a garden