Dig a trench and excavate soil from behind the planned wall as needed. The trench should be at least 8 inches deep. Make the trench roughly level and a few inches wider than the timbers. Excavate far back enough into the slope to accommodate deadmen, or timbers that extend back into the slope for anchors, beginning in the third course.
Place about 2 inches of gravel or sand in the trench. Make sure that it is level and tamp it down.
Drill holes in the timbers for the first course where rebar will be pounded through. Drill a 1/2-inch hole 6 to 12 inches from each end.
Place the first course of timber in the graveled or sand-lined trench. Make sure that it is level and adjust the underlying material and timber as needed.
Pound rebar through the drilled holes to anchor the timbers.
Backfill the area behind this first course and each subsequent course with soil as the wall is being built. Tamp it in firmly.
Stack the second course of timber on top of the first course, staggering timbers so that the joints do not line up between courses. Set each row about 1/2 inch back from the front of the row it sits on, so the wall leans very slightly back into the earth.
Drill holes 6 to 12 inches from the end of each timber and every 4 feet within the timber.
Drive galvanized steel spikes into the holes to attach the course to the one below it. Mark their locations on the face of the timber with chalk or a pencil to avoid them when pounding spikes through the next course.
Lay the third and any additional courses using these techniques with some modifications. In the third row and every second or third course above the third row, place headers and deadmen in the wall. Between each timber in the course, set a header, or timber perpendicular to the wall so that the cut end is exposed. Attach one end to the wall with two spikes and attach a deadman, or shorter piece of timber, to the other end of the header to form a "T" that will act as a buried anchor.
Things You Will Need
- Shovel, spade and other digging tools
- Gravel or sand
- Landscape timbers
- Steel spikes (10-inch, galvanized)
- If drainage could create an issue, place a 4-inch perforated PVC pipe or drain tiles in the trench behind the first course and subsequently backfill the area immediately behind the stacked timbers with gravel or similar aggregate to allow drainage.