How to Rebuild a Rock Wall

Tear down the remains of the existing rock wall by removing the rocks by hand. If mortar was used to connect the rocks, you may need to use a chisel and hammer to break the joints. If a concrete foundation was poured for the rock wall and it is still in good condition, leave it in place.

Dig out an 8-inch trench along the entire length of the desired rock wall if no concrete foundation currently exists. Fill the trench to a depth of 6 inches with concrete and spread it evenly using a trowel or screed. Allow the concrete to set completely before moving on.

Mix up a batch of mortar according to the manufacturer's instructions and stir it until it is completely smooth and free of lump. Use your trowel to spread a 1/2-inch layer of mortar on top of the concrete foundation you just laid.

Place your first rock at one end of the trench, pressing it gently into the mortar you just spread. Position a second rock next to the first, leaving about 1/2 inch of space between the two.

Continue placing rocks along the length of the trench, leaving 1/2 inch of space between each pair of rocks. As you go, lay a level across the gap between two adjacent stones to ensure that they sit at the same height. If adjustments are needed, use a rubber mallet to tap the rocks farther down into the mortar.

Fill a mortar bag with mortar and squeeze it into the 1/2-inch gaps between the rocks.

Spread another 1/2-inch layer of mortar on top of the first row of rocks. Continue building up the wall by placing a second row of rocks on top of the first, centering the stones in the second row over the gap between the adjacent stones in the first row. This is called a running bond pattern and it is a fundamental technique used in masonry.

Build up the wall until it reaches the desired height. Use the mortar bag to squeeze mortar into the gaps between the stones in each new row, then build another row on top. When you reach the desired height for the rock wall, finish the top row with large, flat stones.

Brush away any excess mortar on the outside of the rock wall using a stiff brush. Allow the mortar to set undisturbed for a full 72 hours.

Fill in the landscaping around your rock wall. Use soil or sod to conceal any exposed concrete at the base of the wall and, if you are using your rock wall as a retaining wall, backfill the space behind the wall with soil.