In this video, This Old House landscape contractor Roger Cook shows how to build a wood retaining wall with timber to create a play area.
Wood Retaining Wall Instructions
- Set up wooden stakes and nylon strings to represent the height and perimeter of the retaining wall.
- Stretch another level line near ground to represent the top of the first course of landscaping timbers.
- Dig a trench 12 inches deep around perimeter of retaining wall.
- Use a hand tamper to compact the bottom of the trench.
- Add about 6 inches of ¾-inch stone to trench, then compact the stone with hand tamper.
- Drill a series of 9/16-inch-diameter holes in the first-course landscaping timbers.
- Set a timber in the trench and check it for level.
- Then, stake the timber in place by using a small sledgehammer to drive 4-foot-long rebar spikes through the holes and into the ground.
- When necessary, use a circular saw to cut a timber to length; use a 3-inch-wide foam brush to apply wood preservative to all freshly cut ends.
- Measure across the width, from one side timber to the other, to ensure the two are parallel; make adjustments, if necessary.
- Set the second row of timbers on top of the first course, making sure to stagger end joints by at least 4 feet.
- Use an impact driver to fasten the second course to the first with landscaping screws.
- Pour ¾-inch stone behind the wall, then drape the excavated hillside with landscaping filter fabric.
- Lay a length of 4-inch-diameter perforated pipe on top of the stone, then cover the pipe with more stone.
- Pull the filter fabric over the stone-covered pipe.
- After installing the third course of timbers, make a T-shape dead man (tie-back) from two short lengths of landscaping timber.
- Dig out a T-shape trench into the hillside behind the wall and lay in the dead man.
- Fasten the dead man to the retaining wall with two landscaping screws.
- Then stake the dead man to the soil with two rebar stakes. Install one dead man every 6 to 8 feet around the entire wall.
- Continue building up the retaining wall, using landscaping screws to secure each timber.
- Cover the ground in front of the retaining wall with 2 to 4 inches of bark mulch.