The construction of a retaining wall is often the best way to create usable space in a sloping backyard or to create visual interest on an otherwise flat property. Regardless of whether the wall has been designed for practical or aesthetic purposes, it won’t serve either of these purposes if it hasn’t been designed and built well. In this case, good design really begins below the ground and behind the wall – here are our top 9 tips for ensuring it doesn’t collapse!
Function A retaining wall construction is meant to hold off soil when there is a drastic change in elevation. They’re often necessary on steep blocks to create a safe, usable space for gardens. Some homeowners also choose to build low walls to section off different areas of the garden.
Consent Poorly built walls are prone to bulging, cracking and leaning, which can often mean that they become an eyesore. In more serious cases, they can even topple over. Always check with your local council to see if you need permission to build or to consult with your neighbours.
Pipes & Cables Check your plans against any plumbing or electrical diagrams for your property to ensure that you won’t get any nasty surprises when you start digging. Alternatively, you can get in touch with your local dial-before-you-dig service and they will provide you with a report.
Design A well-designed wall won’t tip over and will support the earth behind it plus any loads that might be applied (such as that from cars and buildings). It will also prevent water from building up behind the wall, which increases the lateral load on it.
Solid Base A solid wall actually starts below ground level. A good base will consist of compacted soil and at least 150mm of compacted sand and gravel. This compacted base ensures that the bottom of the wall remains flat, providing the materials with more contact with those above them.
Good Beginnings Generally speaking, the higher the wall the deeper it needs to begin below the ground. It’s actually a good rule of thumb to have one tenth of the height below ground level (ie a 900mm high wall should have a 90mm base). Also, dig back about 300mm behind for gravel backfill.
Use the Force You can actually use gravity to your advantage during retaining wall construction by stepping the wall back towards the soil. This will ensure that everything is held in place without the need to do too much securing of your own. It also improves the look of the wall.
Drainage Effective drainage is critical for the success of the wall. Without it, pressure will build up behind and lead to bulging or cracking. Three effective ways to ensure good drainage include with gravel backfill, the installation of perforated pipe and the provision of weep holes.
Backfill These walls might look as if they have to hold back huge masses of earth, but they really only have to support a small wedge. Rather than filling that wedge with moisture-loving soil, fill it with sandy gravelly materials that compact easily and allow water to drain.
We hope that you have found the above tips useful in ensuring that your retaining wall construction goes off without a hitch. Ensuring that it has been designed with drainage in mind will go a long way to preventing it from collapsing under the weight of sodden soil or rushing water. This is also why we recommend employing the services of a professional, as they know the ins and outs of construction and can avoid many common issues.
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Sanju k Joined: November 3rd, 2016 Articles Posted: 18
