Boundary Retaining Walls Rights & Obligations

General Principles

Boundary retaining walls are one of the most common sources of neighbour disputes in Australia. The legal framework is less clear than for fences because retaining walls are generally not covered by state Fencing Acts, which deal specifically with dividing fences.

The general legal principle is that the property that benefits from the retained level difference is responsible for the retaining wall. In practice, this usually means the higher property — because they benefit from having their ground level maintained.

Who Pays?

Scenario 1: Natural Level Difference

If the ground has always been at different levels, the situation is less clear. Generally, each property owner is responsible for retaining their own land. If the higher property needs a wall to prevent their soil from encroaching on the lower property, the higher property typically bears the cost.

Scenario 2: One Owner Created the Difference

If one owner cut into the ground (excavation) or filled their property (raising the level), the owner who created the level difference is typically responsible for the retaining wall and its maintenance. This is the clearest situation legally.

Scenario 3: Subdivision

When a developer subdivides land and creates level differences between lots, the developer was typically responsible for initial retaining walls. Once the lots are sold, responsibility usually transfers with ownership of the benefiting (higher) property.

Scenario 4: Shared Benefit

Where both properties benefit from the wall (e.g., it provides usable flat land on both sides), there may be an argument for shared costs. However, this requires agreement between both parties — there's no automatic right to demand shared costs for retaining walls.

The Fencing Act and Retaining Walls

State Fencing Acts (e.g., Victoria's Fences Act 1968, NSW's Dividing Fences Act 1991) govern dividing fences, not retaining walls. A retaining wall is a structural element, not a fence, so Fencing Act provisions for shared costs, fencing notices, and dispute resolution generally don't apply to retaining walls.

However, where a retaining wall also functions as a dividing fence (e.g., a block masonry wall with a fence on top), the fence component may be covered by the Fencing Act while the retaining component is not.

Maintenance Responsibility

The property responsible for the wall is also responsible for its maintenance, including:

• Ensuring drainage systems continue to function
• Repairing cracks, lean, or structural deterioration
• Replacing the wall when it reaches end of life
• Preventing damage to the neighbouring property from wall failure

If a poorly maintained wall fails and damages the neighbouring property, the responsible owner may be liable for repair costs and damages.

Engineering Considerations for Boundary Walls

Retaining walls on boundaries have specific engineering requirements:

• Footings must not encroach on the neighbouring property. This often requires asymmetric footing designs or deeper piers with no toe projection.
• Building permit trigger is lower — 0.6m on or near a boundary vs 1.0m elsewhere in most jurisdictions.
• Survey setout is essential to confirm the exact boundary location before construction.
• Excavation must not undermine neighbouring footings or structures. The zone of influence (typically 45° from the wall base) must be assessed.
• Drainage discharge must be directed within the responsible property, not onto the neighbour's land.

Resolving Disputes

1. Direct communication — talk to your neighbour. Many disputes arise from misunderstanding rather than genuine disagreement.
2. Written agreement — if you reach agreement on cost sharing or responsibilities, put it in writing.
3. Mediation — community mediation services are available in most areas and are significantly cheaper than legal action.
4. Council involvement — if a wall is dangerous, councils may have powers to issue building orders requiring the responsible owner to act.
5. Legal advice — for significant disputes involving structural failure or substantial costs, property/building law advice is recommended.
6. VCAT / tribunal — as a last resort, state tribunals can adjudicate building disputes.

Frequently Asked Questions