Lay Remaining Timbers
In similar fashion, cut timbers to appropriate length, lay in place, and level. Shims can be inserted where needed to make timbers level. To secure timbers, drill holes every two feet and drive 12' galvanized spikes into previous course. For top course, use spikes with a finished head for a more attractive look.
For added stability, it is wise to insert a few timbers perpendicular to the wall. Called "deadmen,” the timbers extend from the retaining wall deep into the ground behind the wall. Drive 2' lengths of rebar through the ends of the deadmen and into the ground.