Watch video of this step.
Offset the joints as you install the second row. Pre-drill holes for the spikes about every 8 inches. Secure this second row to the foundation row with 60d spikes, using the pre-drilled holes.
Build the next row, remembering to stagger the timbers. Again, attach each row to the row below it using 60d spikes (image 1).
Use a hand saw to cut off any excess in order to make the ends of the wall even (image 2). Repeat the process, building subsequent rows and offsetting the timbers so that the ends of every row are in alignment (image 3).
Most retaining walls require drainage and are built with a perforated pipe set behind the wall in a gravel base. Because the grade of this yard has a slight slope that will promote water runoff, we can skip this step on this project, but we will add gravel for drainage and back fill with dirt.
Once you have all the timbers in place (and backfilled), add a top cap.
We're using 2x12 planks cut at 45 degree angles and fitted together in a point. Center the 2x12 cap on the top timber, allowing a 3-inch overhang on both sides. If you need more than one plank to cover the length of the wall, cut them on a 22-degree angle to fit them together.
Attach the top plank using 3-inch wood screws driven every 12 inches.
Then, remove the ends of the boards, leaving a 3-inch overhang.
To finish the project, we round the corners with a simple 45-degree cut (image 4).
With your retaining wall now complete, you can paint or stain it to your taste. Now you can take advantage of the newly leveled area of your yard.