How to Build a Timber Retaining Wall | This Old House

Moments in this video

1. 0:53–1:21 Excavate and Prepare Foundation Trench From Landscape Steps, Step 2: Excavate for First Step

   After marking the wall's footprint, begin digging the trench for the first course of timbers. The trench should be deep enough to accommodate both the timber and a layer of crushed stone beneath it. The video specifies digging down 6 inches for the timber and another 6 inches for the crushed stone, resulting in a total depth of 12 inches. Once the trench is excavated, thoroughly compact the soil at the bottom. Next, fill the trench with a 6-inch layer of 3/4-inch crushed stone. Spread this stone evenly and then compact it firmly using a tamper or plate compactor. This creates a stable and well-draining foundation for your retaining wall.

2. 1:21–2:04 Install and Secure First Timber Course From Landscape Steps, Step 3: Install Retaining Timbers

   Place the first course of pressure-treated timbers into the prepared trench, directly on the compacted crushed stone. Carefully align each timber with your established string lines. To secure the timbers to the ground, drill a series of holes through each timber. Then, drive 4-foot lengths of 1/2-inch rebar through these holes and into the ground below. When hammering the rebar, use a scrap piece of decking to protect the timber surface from damage. Throughout this process, regularly check the timbers for levelness using a torpedo level, both along their length and from front to back, adjusting as necessary until they are perfectly level.

The guide that use this video

• Landscape Steps