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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'll 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.


1Gather your tools and materials

Below are the tools and materials you'll need to complete this project.
Level, drill, safety equipment, saw, shovel, and other tools and materials, laid out on the ground.

2Make 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.

3Measure 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.

A tape measure used to mark out a retaining wall

4Choose 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.

Wooden sleepers in a pile on grass

5Mark 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.

Marking out the dimensions of a retaining wall with a tape measure and a marker paint can

6Set 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.

String being used to measure the width of a retaining wall

7Dig 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.

A Bunnings team member digging a posthole

8Measure 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.

Tape measure and string being used to mark out the position of a retaining wall

9Cut 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.

Retaining wall sleepers being cut to size by a Bunnings team member

10Position 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.

A Bunnings team member securing the vertical post that will hold a retaining wall

11Attach 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.

A Bunnings team member bolting a retaining wall to a vertical post

12Level 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.

A Bunnings team member using a circular saw to cut the top from a retaining wall

13Pour the concrete

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.

Concrete being poured into a posthole to secure a retaining wall's vertical post

14Install 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.

Fertiliser being filled into the gap between a retaining wall and the existing grass verge

15Cap 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.

A Bunnings team member with a finished retainer wall

16Get inspired

Looking for another backyard project? Check out our D.I.Y. landscaping ideas for more great advice.

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Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer. You can also use a simple test kit from Bunnings to indicate the presence of lead-based paint.