How to Build a Free-Standing Rock Wall
A free-standing rock wall, or stacked stone wall, is a form as old as human efforts to fortify and divide. The material, unmortared stone, can be harvested from the land the wall will sit on or purchased from a quarry. Good examples of old stacked stone walls can be found in European and North American rural areas---and in art museums like Storm King in upstate New York, where artist Andy Goldsworthy's wall meanders through the trees.
Site the wall, marking off its shape on one side with sticks and string. Measure the length of the wall and choose the type of stone to build with---round field stone, flattish irregular stacking stone or shaped or dressed stone that is flat and uniform in size. Keep the wall to three feet or lower for stability and take all the measurements to the quarry or supplier to calculate how much stone you will need.
Dig a shallow trench, about 8 inches deep and 2 or 3 inches wider than your planned wall. Fill this trench about 6 inches deep with crushed limestone, called screenings, as a base for the wall, using a level to be sure it is fairly even.
Truck a good selection of all different size stones to where you will begin working, so you can vary the stones and find stones to fit together. Lay a level layer of large, flat stones for the base, fitting them tightly together like a puzzle and shaping them with a hammer so that they fit snugly together. Vary the sizes and shapes somewhat, but use a stable base of stones for this level and always use a large stone at a corner or end. Fill in uneven bits with screenings or smaller stones.
Vary the stones on the next level and all subsequent levels in size---use a large stone and then several smaller stones. Always lay a stone across a "seam," where two stones below it meet, to increase stability. Alternate stones and cover seams in this way for the rest of the wall, one layer at a time. Slant the wall inward toward the top just slightly so that natural shifts will cause the stones to settle down into themselves. On a perfectly vertical wall, time and shifting can dislodge an outer edge and weaken the structure.
Build solid corners or sharp curves that will hold up by alternating the directions of end stones on each level of the wall so they are stacked perpendicular to each other. Another strengthening trick is to lay long stones across the whole width of the wall from time to time, instead of laying all stones lengthwise. Save large, flat "capstones" for the top level to weight everything down and "finish" the wall. Gravity will hold a well-made wall in place, through winter frosts and heavy rains. Tree roots and trees may bend it or scatter parts of it over time---or trees may grow over or around the wall, adding to its ageless appeal.
Things You Will Need
- Measuring tape
- Wooden stakes
- Carpenter's level
- Stone chisel
- Hammer or sledgehammer
- Crushed limestone
- Work gloves
- Steel-toed boots (optional but a good idea)
- Back brace (another optional but good idea)
- Stacking stone is hard on the back. Wear a back brace or back support.
- Protect your toes with steel-toed or heavy work boots.
- Fill in gaps between rocks or plants will eventually take root there and weaken your wall.