How to build a timber retaining wall
Building a retaining wall is a great way to add function and visual appeal to your garden. It not only supports the soil bed, but also makes an impressive decorative feature that will last for many years to come. It’s a project that you can do yourself, all you need is some basic D.I.Y. skills and a little bit of elbow grease.
1. Make a plan
Before you start, plan out the length and height of your retaining wall. We are replacing an old retaining wall, but the same principles apply to one that you start from scratch. Our retaining wall will be two sleepers high, but you can make it lower or higher depending on your requirements.
2. Measure the area
Use a tape measure to work out the length of your wall and how much timber you’ll need. Make sure you leave some space at the back for a drainage pipe.
3. Choose your timber
Choose timber with a minimum rating of H4. We’ve gone for treated pine sleepers, which are designed to go in ground, and will last longer out in the weather and soil.
4. Mark out the posts
Depending on the length of your wall, the sleepers are going to need joiner posts to keep them in place. So, measure and mark the points where the posts will go.
5. Set up a string line
Lay out where you are going to build your retaining wall by running a string line between two stakes at either end. Make sure you set your string line to the back of the retaining wall. This will help you keep your posts in line and your retaining wall straight.
6. Dig holes for the posts
Dig holes for the posts the same depth as the height you want the posts to be above ground. We are also digging a bit further out from the string line because our posts will be in front of the wall.
7. Measure the posts
Measure the height of your posts from the bottom of the hole to the top of the string line. We will be cutting enough timber for three posts, but you may need more.
8. Cut your timber to size
Now it’s time to cut your timber to the sizes you need for the wall and posts. Measure and mark your timber using a pencil and square, then use a circular saw or handsaw to cut the timber.
9. Position the posts
Once you have your timber cut to size, put the posts into position. Make sure they are far enough out to go in front of the wall.
10. Attach sleepers to the posts
Place a wall sleeper behind the first end post, and attach it using your drill. Then attach the other end to the next post. Repeat this process with each sleeper until the bottom row is completed. Then, work your way down the same way for the top row of sleepers.
11. Level the posts
Use a pencil and square to mark the height you need for the posts to be flush with the wall. Then, use your saw to cut off the tops of each post.
12. Pour the conrete
Now, mix up some concrete according to the directions on the packaging and pour it into the holes around the base of each post. Cover each hole with soil and let the concrete set. It’s a good idea to brace your posts first, so that they stay in line when you’re pouring the concrete, and while it’s setting.
13. Install drainage
Pour a layer of scoria behind the wall and place your drainage pipe directly on top. Cover the pipe with another layer of scoria and then cover that with soil. Make sure to run the end of the pipe to a spot where it can be accessed. Direct it to a suitable stormwater drain on-site or into a garden area.
14. Cap it off
You can also attach single sleepers face down on top of your wall. They not only look good but also double as seating when you want to spend some time out in the yard with your family and friends. Then, all you have to do is stain or paint your wall.
Looking for another backyard project? Check out our Landscaping D.I.Y. section for more great advice.