How To Build A Wood Retaining Wall? A Step-by-step Guide

Kenneth Wilson

When you are starting to do some basic landscaping of your home and garden, there will come the point where you need to do something complicated. For many homeowners with larger gardens, one of the scariest things they have to do is build a retaining wall, usually out of wood.

You will have to plan the wood retaining wall and then prepare the area to be installed, digging into the slope. Once the planning is done, you need to anchor the posts, pour cement where needed, and create a drainage layer, eventually filling the slope back up to the wall.

The complete process of building a wooden retaining wall is a lot more complicated and will require a combination of several different skills. Many people worldwide specialize in building retaining walls simply because of the complexity that is inherently involved with the task.

Materials and Tools Needed to Build a Wood Retaining Wall


You will need to arrange several tools along with all the material you will be using to build the wood retaining wall. We recommend getting everything once you have the plan for the retaining wall done, allowing you to measure what is needed and what is not accurately.

We have seen several people who go to buy everything they think they may need, plan the wall, and then try to build it. Usually, these people end up with half-built walls that need to either be demolished or supported later on when all the right stuff has finally been bought.

  • Auger: Augers are tools meant to create almost perfectly round holes, and they will make digging your post holes much easier. We recommend getting one at least two feet in length to ensure the proper anchoring will be possible.
  • Hammer: A simple tool, you will be using a lot of nails, and apart from getting a nail gun, the best tool to do that with will be a good hammer.
  • Shovel: We recommend getting two types of shovels, at the least, flat and capable of digging easily and one that can comfortably be used to scoop material. You will have to dig a few holes even if you have an auger, and there will be a lot of material to move.
  • Saws: Apart from clearing away a few trees that may be in the way of just making the area look clean, you need a saw to cut the timber. The wood wall needs to be cut into shape, and naturally, a table saw, miter saw, and hand saw will be needed.
  • Level: A basic water level will help keep everything nice and level across the retaining wall you are building. If you can afford a laser level, we recommend using one to ensure that the entire project uses the same level.
  • Measuring Tape: Measuring tapes are always a part of any project and will assist in planning the wall and ensuring that your actual wall conforms to the plan.
  • Cement: You will need to anker several posts along the wall to ensure it can handle the pressure from the soil behind it. We recommend making a slightly wet mixture to ensure that it travels to the bottom of the post.
  • Gravel: Gravel in the holes to ensure the posts are level, gravel at the bottom of the wall, and gravel behind the wall. Gravel is one of the most overlooked but most important parts of building your wooden retaining wall.
  • Landscaping Material: You will need to fill in the soil behind the wall that you have removed; we recommend using landscaping soil for this. Not only will this soil be lighter overall, but you can also comfortably rest assured that excess water is not being soaked up.
  • Timber: You cannot use simple fencing wood to build a wood retaining wall; the minimum size of the wood you should be using is 2x4s. For the posts, we recommend getting 4x4s or 6x4s as they will hold the most pressure from the soil being retained.
  • Sealant: Before you install the timber, we recommend applying a sealant on them to ensure that water and bugs cannot easily harm them. Having sealed wood is always better than simply having untreated wood.

Steps to Build a Wood Retaining Wall


Now that we know the tools and materials you will need to build your wood retaining wall, we need to start looking at how to build it. There are eight steps in total that you need to follow to properly build the wall and make it strong enough to last years.

We always recommend that you follow each one at your own pace, ensuring that you are ready to move to the next step. Usually, the entire build process will last two to three days as some steps require time to dry or settle.

  1. 1
    Planning the Retaining Wall: With a pen, paper, and measuring tape, you need to measure out the size of the retaining wall. Calculate how much wood, cement, and gravel you will need and where everything should go.
  2. 2
    Assemble the Wooden Posts: Before you start digging the holes, we recommend cutting all the wood into the size and building the retaining on a flat surface first. This will give you a good idea of where to start and what adjustments need to be made.
  3. 3
    Dig the Holes and the Slope: Once everything is ready, start digging into the slope that you want to retain, ensuring that you dig a few feet deeper to give space to work. Once the slope has been dug out, use your auger to dig the required post holes.
  4. 4
    Add Gravel and Set the Posts: First, add a few inches of gravel to each post hole to ensure the posts are not resting on the mud. Lower the posts into their holes and tie them down with rope or braces when they are perfectly level.
  5. 5
    Pour the Cement Around the Posts: Your cement should already be mixed into a slurry by now. Pour the cement around the posts, making sure that there is half an inch below the top level of the soil, leaving the posts braced and the concrete drying for at least 12 hours.
  6. 6
    Add More Gravel Under the Wall: Once the posts are in, we recommend putting down a layer of gravel around each post and where the soil will be. Ensuring that water can drain out from under the retaining wall instead of settling into the soil.
  7. 7
    Install the Boards: Now that the posts are solid and the gravel has been spread, you can install the boards. Whether you are nailing them, bracing them, or having notches already made, ensure no gaps between the boards; the wall needs to be solid.
  8. 8
    Backfill the Slope Side of the Wall: Once the wood wall has been completely built, put down another layer of gravel. Then start filling in the slope side of the wall using a mixture of the soil and the landscaping material that you should have ready.

Conclusion


A wood retaining wall is a good way to keep soil in check without paying thousands to have a stone or concrete retaining wall built. If you follow the steps properly, your wood retaining wall will last seemingly a lifetime while still being aesthetically pleasing.

Whatever you do, please don’t forget a drainage system; no one wants to deal with a ton of water and soil breaking through their retaining wall!

Kenneth Wilson
October 25, 2021
Contractor Tips, Yard & Garden

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done.

More From This Author


A Guide on How to Remove Epoxy Flooring
Roof Cleaning: Here Are The Methods & Expected Costs
What Size Tankless Water Heater Do I Need? (A Comprehensive Guide)
Tankless Water Heater Pros & Cons: Is It Worth It?
PVC Schedule 40 Vs. Schedule 80: Which Is Better?
How To Train Your Dog For An Invisible Fence (A Comprehensive Guide)