How to Build a Boulder Retaining Wall
Retaining walls are an excellent way to mix up your yard’s landscape. These projects are often on the longer side (two or three days instead of one) and require few home improvement skills. For this project, you will need:
- A shovel
- Plate tamper 48″ level or line level
- Natural boulders
- Coarse gravel
- Roll of soil-blocking fabric
All of your tools and materials can be purchased at a landscaping or home improvement store.
Step 1: To begin, excavate the location of your retaining wall. Lay out the location and excavate the bank approximately 2 feet deeper than the proposed front of the wall. This will take a lot of time and physical energy, so it is important to remain patient. Take breaks if necessary.
Step 2: Dig footing approximately two feet wide and a depth of at least eight inches. Use the level to ensure the base of your footing is even. Then, compact loose soil on the bottom. Try your best not to loosen dirt at the bottom of the footing, and use a plate tamper or shovel to compact the soil.
Step 3: Fill the footing with coarse gravel and spread evenly and compact with a plate tamper or shovel. Level the top of the gravel using your long level or line level, the smooth the surface with a garden rake and plate tamper.
Step 4: Place your first row of boulders, positing the desired sides outward. Put the flattest side on top, which will allow the next layer to fit more easily. Continue adding layers, moving slightly back toward the bank as you go. The wall should have a backward angle at approximately ½” to 1″.
Step 5: Place the soil-blocking fabric on the back of the wall and on the dirt bank. Ensure there is enough fabric layering to cover the dirt. Then, fill the space behind the wall and the bank with coarse stone, stopping around 8″ below the top of the wall.