City of South Perth - Retaining Walls

Retaining Walls

Information on retaining walls.

Last updated on: 07 October 2024

In this article

Retaining walls
When is a retaining wall required?
New retaining walls
Maintaining retaining walls
Raise a request

Retaining walls

A retaining wall is a wall or structure designed and constructed to support soil at a slope steeper than can be naturally supported.

When is a retaining wall required?

Retaining walls are only required where there is a possibility of land being adversely affected by subsidence. Retaining walls may be required where there are varying levels of land, and that land requires supporting at a steeper angle than the land can naturally support itself.

New retaining walls

I need to build a retaining wall. Where is it required to be located?

Where retaining walls are required, it is preferred that retaining walls are built within the boundaries of the property where the land is proposed to be altered. It is important to ensure that privacy is maintained when adding fill to a property. In most instances a 1.8m dividing fence on top of a retaining wall is appropriate to prevent overlooking to an adjoining property. Where a retaining wall is not built next to a property boundary and is higher than 0.5m an additional privacy screen of 1.6m may be required. Retaining walls may only be built across boundaries where there is written agreement between the affected neighbours. Where the construction of a retaining wall encroaches across a boundary, a form BA20 must be completed and submitted with the building permit application. If development (planning) approval is required, both landowners will usually need to agree to the development (planning) application.

Do I need a building permit?

The Building Regulations 2012, Schedule 4, Clause 2 Item 6 states that: 'Construction, erection, assembly or placement of a retaining wall that: (a) retains ground no more than 0.5m in height; and (b) is not associated with other building work or with the protection of land adjoining the land on which the retaining wall is located; and (c) is not work of a kind to which section 76 (Encroach), 77 (Adversely affect), 78 (Protection not beyond boundary) or 79 (Party walls not to be affected) relates.' A retaining wall that does not meet any of (a), (b) or (c) will require an application for a building permit.

Do I need development (planning) approval for my retaining wall?

An application for development approval is generally required for residential properties where:

Retaining is within the street setback area and has a height of more than 0.5m from natural ground level. This applies to retaining walls associated with fill and excavation
Retaining wall is within 1.0m of an adjoining property boundary (not being a street boundary) and has a height of more than 0.5m from natural ground level. This applies to retaining walls associated with fill only
Retaining walls and fill with a height of more than 0.5m from natural ground level that are within 7.5 metres of a property boundary and no screening is provided to prevent overlooking to an adjoining property.

If your proposal does not meet the above requirements or any other requirements of the Residential Design Codes, and/or the development provisions of a local structure plan or the City's Residential Development Local Planning Policy, you may lodge a development application to seek that the City exercise its discretion. It is strongly recommended that you submit comments and signed plans from the owner(s) and occupier(s) of adjoining property if your proposed development has the potential to impact on other property.

Maintaining retaining walls

Who is responsible for construction and maintenance of a retaining wall?

Owners of retaining walls are required to maintain their walls in a structurally sound manner. The party who changes the lie of the land either by excavation or building up (fill) is responsible for building a retaining wall. If both neighbours have altered the lie of the land each neighbour will be responsible for the construction and maintenance of the retaining wall to the extent of their own alteration. Note: A dividing fence is not considered suitable for retaining soil.

Who pays for the retaining wall between neighbours?

Each landowner has an obligation to retain soil where necessary resulting from earthworks on their property. Adjoining owners who have both undertaken earthworks are advised to negotiate a proportional based agreement when retaining walls are required along a common boundary for a dividing fencing or landscaping works. When an agreement cannot be reached through arbitration and mediation, owners should seek legal advice.

Retaining wall between mine and my neighbour’s property is collapsing. Who is responsible?

In some instances, it may be difficult to determine who constructed a retaining wall and at what point in time. It can also be difficult to determine to what extent each property owner is liable for a collapsing retaining wall. Property owners should get their own independent legal advice. The owner will be required to consult a practising structural engineer to determine what action, if any, is required to restore the structural integrity of the wall. The cost for the structural engineers' services is the responsibility of the owner.

Raise a request

To request further information on retaining walls, or to query requirements for building a retaining wall, raise a request below.
An officer will respond within 10 business days.

Request Further Retaining Wall Information

Query Retaining Wall Application Requirements

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