Retaining Wall and Fence: Do You Need Both?

On flat blocks, fencing is straightforward. But across Brisbane and Greater Queensland, plenty of properties have slopes, level changes, and uneven ground that make things more complicated. In those situations, the question often comes up - do I need a retaining wall, a fence, or both?

The answer depends on your block and what you are trying to achieve.

When You Need a Retaining Wall

A retaining wall holds back soil where there is a change in ground level. Without one, the soil will gradually shift, erode, and potentially undermine anything built nearby, including your fence.

If your property has a level change along the boundary, even a relatively modest one, a retaining wall may be necessary to stabilise the ground before a fence can be installed. Building a fence directly on unstable or sloping ground without addressing the soil retention first is a recipe for problems.

When You Need Both

The most common scenario in Brisbane is a property where the ground level differs on each side of the boundary. In that case, you typically need a retaining wall to hold the higher side, with a fence built on top or directly behind it.

This combination is particularly common in suburbs built on hilly terrain, which covers a large portion of Greater Brisbane. New housing estates with cut-and-fill earthworks also frequently require retaining walls along boundaries before fencing can go in.

Common Materials

Concrete sleepers are the most popular choice for retaining walls in Brisbane. They are strong, durable, and handle moisture well. Concrete sleeper walls use steel or concrete posts with horizontal sleepers stacked between them. They suit most residential applications and come in a range of finishes, from plain grey to textured options that resemble stone.

Timber sleepers are another option, particularly for smaller walls or garden-level retention. Treated hardwood sleepers can look great in the right setting, but they do require more maintenance than concrete and have a shorter lifespan in Queensland conditions.

For retaining walls up to one metre in height, a building approval is generally not required in most Brisbane council areas. Walls over one metre typically need engineering and council approval.

Integrating a Retaining Wall and Fence

When you need both a retaining wall and a fence, how they connect matters. A fence sitting on top of a retaining wall needs to be anchored properly into the wall or into dedicated posts set behind it. Simply bolting a fence to the top of a wall without adequate fixing is a common shortcut that leads to failure.

The combined height of the wall and fence also needs consideration. If the retaining wall is 600 millimetres and the fence is 1.8 metres, the total structure from the lower ground level is 2.4 metres. Depending on your council area, this may trigger additional requirements.

Planning the wall and fence together from the start, rather than treating them as separate projects, usually results in a cleaner finish, better structural integrity, and lower overall cost.

Height Limits to Keep in Mind

In Queensland, retaining walls under one metre generally do not need council approval. Fences under two metres on a boundary are typically exempt from building approval as well. But when you combine the two, the total height as seen from the lower side can exceed the thresholds, so it is worth checking the rules for your specific council area before committing to a design.

The Simple Version

If your block is flat, you probably just need a fence. If there is a slope or level change along the boundary, a retaining wall may be needed first. And if you need both, plan them together for the best result.

We build both retaining walls and fences across Brisbane, so if you are not sure what your property needs, we are happy to take a look and give you a clear recommendation.