Retaining walls and site works – approval requirements
A retaining wall is a wall or structure designed and constructed to support soil at a slope steeper than can be naturally supported.
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.
Responsibility for constructing 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 (cut) 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.
A dividing fence is not considered suitable for retaining soil.
Location of retaining walls
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 on 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 a development (planning) application is required, both land owners will need to sign the development (planning) application forms.
Planning requirements
Retaining walls and site works on a residential property will require a development (planning) application where it does not meet the requirements of the Residential Design Codes (R-Codes), The City’s Residential Development Local Planning Policy (RDLPP), Development in Housing Opportunity Areas Local Planning Policy (HOALPP) or structure plan (if applicable).
For a single house or grouped dwelling a development (planning) application is not required for your retaining walls and site works if it complies with the following:
- Retaining, fill and/or excavation between the street boundary and the street setback does not exceed the maximum heights for your R-Code density (see table 2 below).
- Retaining and fill behind the street setback has a height and setback in accordance with table 1 below.
- For excavation and associated retaining behind the street setback there is no restriction.
Additional requirements may apply if:
- Retaining and fill greater than 0.5m is within 7.5m of a side or rear boundary and no screening is provided to prevent overlooking in the neighbouring property (e.g. when a dividing fence is not built on top of the retaining wall). In these instances, screening is required to be 1.6m above the finished ground level and be of a permanently fixed, durable material.
- A street wall or fence is proposed above the retaining. Refer to the street walls and fences factsheet.
- The property is within a structure plan area.
Table 1:
| Height from Natural Ground Level | Minimum Setback to a Property Boundary |
| 0.5m or less | 0m |
| 1m | 1m |
| 1.5m | 1.5m |
| 2m | 2m |
| 2.5m | 2.5m |
| 3m | 3m |
Table 2:
| R-Code Density | Street Setback | Maximum Height of Retaining Walls, Excavation and/or Fill in the street setback |
| R20 | Street the house faces: 6m, or the setback between the street and house, whichever is the lesser.
Other streets (corner property): 1.5m |
1m Any retaining and fill within 1.5m of where a driveway meets the street boundary shall be a maximum height of 0.75m. |
| R20/25*
R20/30* R20/40* R20/60* |
Street the house faces: 4m (2m for R20/60)
Other streets (corner property): 2m |
0.5m |
| *For lots with a dual-density code (e.g. R20/40) the requirements only apply if the property is developed at the higher density (e.g. R40). If your property has not been built to the higher density, refer to R20 requirements. | ||
Building permit requirements
A building permit is not required when the retaining wall complies with all of the following:
- The structure retains ground no more than 0.5m in height; and
- The structure isn’t associated with other building work or with the protection of land adjoining the land on which the retaining wall is located; and
- The structure does not affect other land that requires consent.
A retaining wall that does not meet all of the above will require a building permit.
Building permit application forms (certified or uncertified) are available from the Department of Mines, Industry Regulation and Safety website. Certified building permit applications must be accompanied with a Certificate of Design Compliance.
Please refer to the City’s Uncertified Building Application Checklist – Retaining Walls (Class 10b) for information required to be provided with the Building Permit Application (BA2 form).
Retaining wall disputes
It is always advisable to attempt to resolve issues or differences of opinion verbally by talking to the other party and trying to find common ground where issues or disputes can be resolved.
Retaining Wall Dispute Guidelines (refer to link below) have been designed to assist with the process of dealing with issues which relate to retaining walls disputes. By following the steps outlined carefully, resolutions to issues may be more readily resolved between the parties involved.