Retaining walls have played an important part in landscape design plans for hundreds of years, and due to the sheer variety of garden and landscaping needs, retaining walls can be successfully erected and utilised for a wide range of purposes. Here’s a brief description of what a retaining wall is, and a few examples of why they are so important in many effective landscape designs.

What are retaining walls?

A retaining wall is first and foremost a structural feature which is relatively rigid and supports soil laterally so it can be retained at different levels on either side of the wall.

There are a number of different types of retaining walls which use different methods to retain the soil beneath them. Common types include gravity walls; which tilts back slightly towards the soil it supports and has a base buried under the soil to accommodate pressure, cantilever walls; which are L-shaped with foundations that stretch back under the compacted soil the walls support, and sheet piling walls; which are often supported with tie-back anchors that are planted in the soil behind the wall to help keep the wall vertical.

If you’re planning to include a retaining wall within your landscape or garden design, be wary that Perth retaining walls above 500mm in height require Building Permit and Planning Approval from your local council.

Retaining wall materials

Common materials for retaining walls include stone, brick and concrete. Retaining walls can also be constructed from timber, but this is not the most effective option as they can be easily impacted by termites or wood rotting. Use of stone, brick and concrete for retaining walls should be very considered and well-planned, as if a retaining wall made from these materials doesn’t have strong enough foundations, it will falter very quickly.

Uses of retaining walls

Common uses of retaining walls include;

  • providing effective drainage and irrigation for soil by diverting water,
  • holding up uneven sections of soil (for instance, on a hill),
  • preventing soil erosion,
  • creating interesting design features within a garden.

The latter use of a retaining wall, involving landscape design, has grown in popularity in recent decades. Many modern gardens with flower beds, rock gardens or other landscaping projects like vertical gardens will utilise a strong retaining wall as a supporting structure.

Why do I need retaining walls?

Though we’ve outlined a few functional and aesthetic reasons why you may install a retaining wall in your garden, in simple terms, you’ll need a retaining wall if you need to hold up ground soil that would otherwise drift down, or if you need a structure that can support soil by preventing erosion and facilitating irrigation.