Retaining walls 101
A retaining wall is designed to hold back soil where there’s a big change in elevation. It can create extra outdoor space, stop erosion and can even be used to create planting beds, giving a flat yard a lift.
Ready to take your outdoor space to the next level? Here are four things you need to know about retaining walls.
1 Put your best footing forward
Like any structure, your retaining wall needs a solid base, set below ground level. Footing can be made using compacted road base or reinforced concrete. Depending on your retaining wall height and drainage, the footing may need to be wider, deeper (or both) than your retaining wall. Another factor in how large your footing needs to be is soil quality, especially if you have poor soil made up of sand or clay.
2 Go with the flow
Good drainage is key. If there’s no drainage, pressure will build up behind your wall and create bulges or cracks, undoing all your hard work. To stop this from happening, make sure you backfill with an aggregate (like gravel or blue metal). As the name suggests, backfill needs to go behind the wall and will need to be at least 30 centimetres deep. Drainage should be created with an agricultural (ag) line along the backfilled portion of the wall. Creating weep holes in your retaining wall will also let water drain through.
3 Have your fill
The rest of the space behind the wall can be filled with compacted soil. If you want to landscape behind your wall, include a 15 centimetre or more layer of a quality garden mix on top.
4 Reach new heights
The height of your wall will determine how much weight it can bear. Normally, residential retaining walls are between 0.9 and 1.2 metres high, which can provide excellent strength, combined with the correct footing and drainage. Cantilevered or setback walls will also offer extra support. If the wall you need is more than 0.6 metres high, you can create a series of retaining walls for a terraced effect.
If you need a wall that’s above 0.6 metres, or if you’d simply like to have the dirty work done for you, let us put you in touch with one of our Flower Power Services landscapers.
Please note: Before constructing any retaining wall, please check with your local council or a structural engineer to check what height is allowed to be built without lodging a development application, or if a structural drawing is required.