Retaining walls are essential for managing changes in ground levels, especially on Perth’s sloping blocks and in new housing estates where land is cut and filled to create buildable sites. But when a retaining wall sits near a boundary, issues can arise, and if you’re not careful, it can lead to costly disagreements with neighbours or even legal disputes. Understanding the rules around retaining walls and property lines is the key to keeping things compliant, respectful, and drama-free.
Why Retaining Walls Cause Neighbour Disputes
Most disputes happen because of three main misunderstandings:
- Who is responsible for building or paying for a retaining wall
- How soil levels between properties should be managed
- Where the retaining wall can legally be positioned
In Perth, these rules are clearly outlined by WA legislation and local council policies, but many homeowners aren’t aware of them until problems arise. Let’s break them down.
Who Is Responsible for the Retaining Wall?
In Western Australia, the rule is simple:
Whoever changes the natural ground level is responsible for retaining their own soil.
This means:
- If you excavate your block and make it lower, you must retain the cut.
- If you fill your block and make it higher, you must retain the fill.
- If a developer made the land levels uneven before sale, they are responsible for the original retaining (and this is usually completed before settlement).
Many disputes occur when owners assume the cost should be shared, but fencing and retaining walls are completely separate structures with different rules.
Fences ≠ Retaining Walls
A boundary fence does not count as a retaining structure and cannot legally be used to hold back soil. If one property needs a retaining wall for support, the owner who benefits must build and pay for it.
Where Can a Retaining Wall Be Built?
In Perth, a retaining wall can be built:
- On your property
- Set back from the boundary
- Or directly on the boundary, but only if it retains your own soil
It cannot be built on a neighbour’s land without a written agreement.
Building on the boundary
If your retaining wall sits directly on the boundary, it must:
- Be engineered and certified
- Be able to withstand long-term soil pressure
- Do not divert water onto your neighbour’s property
- Comply with council setback requirements
Most councils allow retaining walls on boundaries only when they support your own altered ground level.
Do You Need Your Neighbour’s Permission?
In most cases, no, you do not need a neighbour’s approval to build a retaining wall, as long as it is on your land and retains your soil.
However, you must consult your neighbour if:
- You need access to their land during construction
- The retaining wall affects their fence line
- The wall impacts drainage onto their property
- The wall requires temporary support on its side
- You plan to change levels that affect shared boundaries
Good communication prevents disputes before they start.
Council and Engineering Requirements Near Property Lines
Perth councils take retaining walls near boundaries seriously because poor construction can cause major issues, including:
- Soil collapse
- Water runoff problems
- Boundary encroachment
- Fence movement
- Structural damage to neighbouring land
Walls under 500mm
Usually don’t require council approval, BUT engineering may still be recommended if the wall is close to a boundary.
Walls 500mm–1.0m
Some Perth councils require approval in this range, especially on boundaries. Almost all require engineering if the wall supports additional loads (fences, driveways, pools).
Walls 1.0m and above
- Require engineering certification under AS 4678
- Require development approval
- May require a building permit
- Must meet strict structural and drainage standards
When in doubt, get advice; building without approval can lead to orders to demolish or rebuild.
Common Boundary Disputes — and How to Avoid Them
“Who pays for the retaining wall?”
As mentioned, whoever changes levels pays. If your neighbour has cut or filled and left you with unsupported soil, they are responsible.
“Your wall is on my land.”
Surveying prevents this. Before building, get:
- A title boundary plan
- A licensed surveyor to mark the line
“Your drainage is flooding my yard.”
Proper drainage design prevents runoff. A compliant retaining wall must:
- Include ag pipes
- Use free-draining gravel
- Manage water flow legally
“The fence is leaning because of your soil.”
Fences cannot retain soil. If your soil is impacting a fence, you must install proper retaining.
“Your retaining wall is unsafe.”
Retaining walls built without engineering can collapse over time. Always choose an engineered design to protect both properties.
How to Avoid Neighbour Disputes Altogether
Here are simple steps to keep things smooth and compliant:
Communicate openly
Tell neighbours your plans early. A quick conversation avoids confusion later.
Stick to your side of the boundary
Never assume, always confirm your exact boundary with a surveyor.
Follow Perth council guidelines
Each council has its own retaining wall requirements.
Use certified engineers
This ensures the wall is structurally sound and legally compliant.
Choose experienced retaining wall contractors
Professionals know how to build without causing issues to neighbouring land.
At Structural Retaining Walls, our goal is to build strong, compliant retaining walls that protect your property and keep neighbour relationships intact.
Need Help With a Boundary Retaining Wall?
If your retaining wall is near a property line, don’t risk disputes or compliance issues. Our goal is to build strong, compliant retaining walls that protect your property and keep neighbour relationships intact.