How to Build a Permanent Earth Retaining Wall

Measure the area where you want to build a retaining wall. Mark the area with spray paint, a garden hose or anything similar.

Determine how high the wall needs to be, and purchase the appropriate size rock for the wall. Use a string and stake with a level, starting at the highest point and measuring from the string to the ground. It is better to build two smaller terraced walls than one large and tall wall. Smaller walls require smaller stones, while the taller walls need larger stones and deeper footings.

Dig a trench at the base of the proposed wall 6 inches deeper than the depth of one flat landscaping stone and wide enough for 3 inches of gravel in the front of the stone and 6 inches of gravel at the back.

Fill the bottom of the trench with 4 inches of 1/4-inch gravel, and level it with a garden rake. Tamp the gravel firmly with a pole tamper.

Pour a 1-inch layer of builders sand over the gravel, and tamp it again to smooth and solidify the base.

Set the first row of flat landscaping stones in the trench at slightly below grade level. Check the stones with a 12-inch level to make sure they sit level in both directions; otherwise, the rest of the wall will be skewed.

Install a 4-inch perforated drainage pipe with the holes on the top along the back of the wall on top of the compacted stone and sand. The pipe should descend 1 inch for every 10 feet of pipe to drain the water away from the back of the wall.

Fill in the back of the wall between the first stone and the retained soil with 1/4-inch gravel, covering the drainage pipe.

Lay the second layer of stones, using the connecting pins to hold the layers together. Keep each stone flush with the next. Fill in the area between the stone and the soil with more gravel and tamp it down to make it firm.

Continue layering the rocks and adding backfill of gravel until you have reached the top level of stone. Use mortar to hold the top level of stone in place. Backfill at least 6 inches along the back of the wall with the 1/4-inch gravel, and fill the rest of any open area with topsoil.

Mulch over the top of the gravel up to the stone with 4 inches of hardwood mulch. Mulch at the bottom of the wall over the front area of gravel with 4 inches of the hardwood mulch.