Advice on Retaining Walls

Use Stackable Stones

For retaining walls lower than 4 feet, stackable stones offer the easiest installation. These stones are usually made from concrete, but feature a decorative front that provides an attractive appearance for the wall. The backside of the stones has a lip that allows them to stack securely on top of one another by forming an interlocking joint. They are also available in a wedge shape so you can create a curve in your wall if necessary. If you are building a retaining wall that is higher than 4 feet, additional reinforcement is required for the structure, so stackable stones are generally not recommended.

A retaining wall must be able to bear a significant amount of pressure. Burying the first layer of stones beneath ground level can help stabilize the wall by providing a solid mass for it to press against. When you have settled on the wall's location, dig a trench that is slightly wider than the stones and deep enough that you can sink the first layer of stones below the ground. Try to keep the trench as level as possible, and avoid disturbing the surrounding soil by cutting straight down with your shovel. When you reach the bottom, use a soil tamper to pack down the dirt. It is a good idea to add a layer of rock dust or gravel to ensure that the trench is properly leveled and tamped before you place the first layer of stones.

As you finish each row of your wall, add backfill to ensure that it has sufficient reinforcement and drainage. Crushed stone and gravel are effective backfill options. You may want to cover your wall with landscape fabric to keep it from getting dirty as you work. Place your backfill material against the back and sides of the stones. Layer some dirt behind the backfill, and use your soil tamper to pack the materials down. Add a layer of topsoil for a finished look.

Adding capping to your retaining wall not only provides a finished look, but it also helps protect it from erosion and weather-related damage. Capping stabilizes the walls as well. As with the stackable building stones, capping or topper stones usually feature a lip on their backside so they can securely fit in place on the top of the wall. However, they have a flat-top surface with a smooth look that provides the wall with an attractive, polished appearance.