Another project with many different applications, it pays to know how to build a retaining wall in wood.
Stone is popular and sturdy for backyard and even commercial use. You can pick up any number of different styles, sizes and colors at your local building supplies store. But if you’re looking for a natural, economical product, look no further than Pressure Treated wood. You can use garden ties, 4×4, 5×5 or 6×6 timbers to build a strong, long lasting and maintenance free retaining wall. Perfect for around your garden, to level off a sloped yard or to retain soil along your driveway, backyard wood walls are a cinch to build with a little bit of prep and some muscle.
Start with the site preparation. If you need to excavate, make sure you dig all the way back to the length of any necessary tiebacks (sometimes called deadmen). Here’s what that means. If you’re building a wall higher than 18” off the ground, you will need tiebacks – timbers that are incorporated into the face of the wall, but run back into the earth behind the wall (like a “T”). These help to form a frame 3 to 4 feet back from the wall face and will be covered in back fill or gravel once the wall is completed. So, if these are necessary, be sure to dig back 3 to 4 feet from the wall placement in order to properly accommodate them.

Although the landscape fabric and rebar are unnecessary, this diagram gives you a pretty good look at the layout of a wood retaining wall.
Lay a base of gravel about 6” thick and tamp it down (you don’t need equipment for this – just make sure it’s packed as well as you can). This is to ensure your first course will have stability; the gravel won’t wash away as soil would.
Be ABSOLUTELY sure that your bottom layer or course is level. This is probably the most important step and should be double and triple checked with an actual level (no eyeballing this one). Remember that your bottom layer is the furthest out, as all subsequent levels will be set back from it in a step pattern.
If your completed retaining wall will be 18” high or less, continue to lay the courses on top of the first, LEVEL layer, placing them ½” back from the front of the timber.
If you’re looking at doing tiebacks, start them at the second layer. Space them 6 to 8 feet on center and lay them back 3 to 4 feet. In order to keep these first tiebacks level, put a small timber underneath the back end (like a small “T”) – there’s no need to lay an entire timber there, just scrap pieces will work. After you’ve laid the tiebacks, connect all of them with a timber across the top. This will give you a spot to lay the next set of tiebacks – which are placed every second course on the wall. The tieback system should look like a framed echo of the retaining wall face.
Tie all of the timber together using 10” spikes (if your wall is made of 6×6 timbers) or a spike long enough to go through both. Space these 16” apart and don’t forget to attach the tiebacks at the wall and on the framework as well.
You will need some drainage in your retaining wall system as well. Lay a big “O” or drainage tile across the bottom of the wall, behind the first course. Then backfill with clear gravel to cover the drainage tile. This will allow the water to run down and into the pipe, which will then direct it away from the wall to prevent heaving and soil erosion.
A wall that’s higher than 18” requires a lot more skill and equipment, not to mention muscle to carry all of that lumber to the site. Look to hire a professional if you’re not confident. You don’t want to put all of that effort in just to have the wall sag or fall over, which WILL happen if all of the elements are not done properly.
For anything below 18”, have at it. With the know-how, some digging, gravel and a few layers of timber, your project will be done perfectly.
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