Step-by-Step Wood Retaining Wall Instructions

Retaining walls are great for reshaping the slope of any property to create a level area. From children’s play areas to driveways, gardens, and more, retaining walls keep soil and vegetation in place while leveling the area for use. 

Most retaining walls are made of heavy, sturdy material such as masonry and large timbers. Retaining walls made of these materials require anchoring deep into the ground with the weight of the surrounding ground as support. To build retaining walls of this type requires know-how and brute strength. 

There’s another type of retaining wall that isn’t as difficult or heavy to build. Made of pressure-treated lumber, this type of retaining wall is easier to build but adds plenty of stability for creating those level, usable areas you desire on a slope. 

Below, we run through some simple steps to building a wooden retaining wall in your yard. 

Steps to Building a Wood Retaining Wall

These steps will help you build a 16-foot retaining wall that stands 24 inches high.  All lumber should be pressure-treated. 

Materials

  • (6) 8ft. 2 x 6 boards
  • (6) 8ft. 2 x 8 boards
  • (8) 50-pound bags quick-set concrete
  • (8) bags of 7/8-inch drainage gravel
  • (2) wooden stakes
  • Twine or mason line
  • 16d hot-dipped galvanized nails
  • Wood preservative

Tools

  • Posthole digger
  • Hammer
  • Shovel
  • Saw
  • Level
  • Measuring tape

Step 1: Stake Out the Area

Pound a stake at one end of the area where you plan to build the wall. Measure 16 feet and pound another stake. Tie a piece of twine between the two stakes and pull it tight. 

Step 2: Cut the Slope

Using your shovel, dig two feet back into the slope. 

Step 3: Dig a Trench for the Wall

Using your shovel, follow the line and dig a trench five inches deep for the wall to rest in. Level it by placing a board in the trench with a bubble level on top. 

Step 4: Mark Post Holes

Measure 2-foot increments between the two stakes already in place. This represents where you need to dig post holes. Pound a stake at each two-foot measurement. 

Step 5: Dig the Post Holes

Use the post hole digger to dig the post holes where you marked the 2-foot increments in the last step. Dig the holes 28-inches deep to accommodate the posts and a bed of gravel underneath. 

Step 6: Add the Gravel

Add four inches of gravel to each post hole. 

Step 7: Set the Posts

Cut four of the 2 x 6 posts in half. Apply wood preservative to the cut ends of each piece. Working one hole at a time, place a post in the hole and pour a bag of quick-set concrete in the hole followed by the recommended amount of water. Allow the concrete to set before moving on to the next post. Use a laser level to ensure each post is level with the next. 

Step 8: Add Gravel Beneath the Wall

Add two inches of gravel to the trench where the wall will rest. This will allow for drainage, so the wood doesn’t rot. 

Step 9: Install the Boards

Starting at the top of the posts and working down, install the 2 x 6 boards across the posts. The bottom boards will be about two inches below the ground. 

Step 10: Backfill

On the slope side, use any remaining gravel to fill in along the wall. This will promote drainage. Fill the rest of the cavity with soil.