How to Engineer a Four Foot Retaining Wall

Place a row of pavers onto the ground where you are building the wall, and spray paint two lines onto the ground. Paint one line 3 inches in front of the paver stones, and the second line 8 inches behind the pavers. Remove the paver stones after you spray paint the lines.

Dig a 12-inch deep trench in the ground between the lines. Rake the soil and tamp it down to compact it.

Pour 3 inches of crushed limestone into the trench and tamp it down. Install steel edge restraints in the trench 4 inches from the back edge of the trench.

Add another 3 inches of crushed limestone along the front of the trench inside the edge restraints. Tamp the limestone down.

Lay a paver stone on top of the raised area of limestone in front of the edge restraints at one end of the trench, setting it about 3 inches back from the front edge of the trench. Place a level on top of the paver, and check it for level going both east-west and north-south. Tap the paver stone down with a rubber mallet to level it if necessary.

Place the second paver into the trench next to the first one. Lay the level across the top of both pavers, and tap down to second paver so that it's even with the first paver, if needed. Continue setting paver stones in the trench until you reach the end, using the same process to ensure that the stones are at the same height. If you can't fit a full paver into the trench at the end, cut it with a wet saw.

Add crushed limestone on top of the limestone behind the edge restraints, using less at the end where you want to direct the water to, and more at the opposite end. Smooth the surface with a rake, and slope the limestone down toward the lower end at a rate of about 1 inch for every 100 feet of run (length) of the wall.

Lay landscaping fabric on top of the crushed limestone in the back of the trench, behind the edge restraints. This helps stabilize the base.

Add a 1-inch layer of drainage aggregate on top of the landscaping fabric. The aggregate is made up of rocks 2 to 3 inches apart that allow water to flow around them at a slow rate.

Wrap landscaping fabric around the drain tile. The drain tile is plastic pipe that contains holes that allow water to flow through. Lay the drain tile into the drainage trench.

Cut a paver stone in half with the wet saw and use masonry adhesive to glue it to the top of the first paver stone you laid. Doing this allows you to stagger the stones in the second course, which strengthens the wall. Set the cut stone back about 3/4 inch from the front of the first stone. Install the second course of paver stones on top of the first course, setting them back from the first course and gluing them with the masonry adhesive.

Lay another course of pavers, staggering them from the pavers in the second course.

Remove the dirt from the front edge of the hill behind the wall until it is 8 inches away from the back edge of the paver stones.

Place landscaping fabric over the exposed soil on the face of the hill to help stabilize it.

Fill the space between the back of the wall and the hill with drainage aggregate, and tamp it down.

Add more courses of paver stones to the wall until it reaches 4 feet high. Stagger the pavers in alternating rows as you lay them.

Fill the gap between the wall and the front of the hill with more drainage aggregate until it's about 3 inches beneath the top of the wall. Tamp the aggregate down, and cover it with landscaping fabric.

Fill the last few inches of space behind the wall with soil. Place plants into the soil, if desired.