Retaining Wall Regulations Victoria: Do You Need a Permit?

Retaining wall regulations in Victoria are shorter than most people expect, but the conditions attached to the exemption catch many owners out. This guide sets out what the regulations actually say, how building surveyors apply them in practice, what happens when a wall is built without a required permit, and when a structural engineer needs to be involved.

What the Retaining Wall Regulations in Victoria Say

Building permits in Victoria are governed by the Building Act 1993 and the Building Regulations 2018. Schedule 3 of the Regulations lists building work that is exempt from needing a building permit. For retaining walls, the exemption applies only where all three of the following are true.

Because the building permit system operates under state regulations, the exemption is the same across Victoria. What varies is how individual building surveyors assess a particular wall, and whether the local planning scheme separately requires a planning permit for earthworks (covered below).

Retaining Walls That Need a Permit at Any Height

In practice, building surveyors treat the following walls as requiring a building permit regardless of height, because they fail the second or third exemption condition.

• Walls that support house footings, sheds, garages, pools or spas
• Walls that hold up a neighbour's land, which is common on subdivided and sloping estate lots
• Walls with surcharge above them, such as a driveway, parking area, fence or building
• Walls built as part of a new dwelling, extension, pool or other permitted project
• Tiered walls close enough together that they act as one wall retaining 1 metre or more

Boundary Retaining Walls

Walls on or close to a title boundary are the most common source of permit problems. A boundary wall usually retains either your ground or the neighbour's, and where it retains the neighbour's ground it is protecting adjoining property and needs a permit. A fence built on top of a boundary retaining wall adds surcharge load and changes the effective height of the fence for siting purposes, which can trigger a separate siting assessment and, in some cases, the report and consent of council.

Where the wall crosses or sits within an easement, Regulation 130 requires the report and consent of the authority the easement is vested in (often the council or water authority) before the building surveyor can issue the permit. Walls near sewers and stormwater drains also need to consider the asset owner's build over requirements.

Retaining Walls on Sloping Estate Lots

New estates in Melbourne's growth corridors (Casey, Cardinia, Wyndham, Melton, Hume and Whittlesea) are often benched during subdivision, leaving level changes along side and rear boundaries. When a house is built, the builder's site cut and the fill under the slab frequently need retaining along those boundaries. Because these walls are associated with the new dwelling, and often hold up a neighbour's lot, they generally form part of the house building permit or need their own permit, even where the level change is well under 1 metre.

• Check the estate's engineering plans and any design guidelines for existing retaining walls and levels
• Confirm who owns and maintains any walls built by the developer along the boundary
• Allow for the neighbour's future site cut or fill, which can surcharge or undermine your wall
• Make sure the wall's drainage discharges to the legal point of discharge, not onto the neighbour's lot

What Happens If You Build Without a Permit

Building a retaining wall that needs a permit without one is a breach of the Building Act 1993. The consequences can extend well beyond the cost of the original wall.

Property Sale Issues

Unpermitted retaining walls regularly surface during a sale. A buyer's building inspector or conveyancer may identify them, and the buyer may seek rectification, a price reduction or withdraw from the contract.

Insurance and Liability

A wall built without a permit and engineering has no record of being designed to the Australian Standards. If it fails and damages a neighbouring property, the owner may be personally liable and insurance may not respond.

Retrospective Approval

It is possible to seek approval for an existing wall through a building surveyor, usually by way of a building permit for the wall as built or for rectification works. This commonly requires a structural engineer inspection, exposure of the footing and drainage to confirm how the wall was built, and engineering certification or a strengthening design. Retrospective approval is almost always more disruptive than doing it correctly from the outset.

When You Need a Structural Engineer

A building permit and an engineered design are two different things. The permit is the statutory approval. The engineering confirms the wall will safely resist the soil pressure, surcharge and water pressure acting on it. For walls that need a permit, most building surveyors require structural drawings and calculations from a registered engineer, designed to AS 4678 (Earth retaining structures) and, where applicable, AS 3600 (concrete), AS 3700 (masonry) or AS 1720 (timber).

Even where a wall is exempt, engineering is sensible for walls approaching 1 metre, walls in reactive Melbourne clay, walls close to buildings or boundaries, and any wall where failure would damage property. Drainage behind the wall is as important as the wall itself, and is the most common cause of failure in walls that were never engineered. See the guide to retaining wall drainage pipe for more on this.

Principal Built Engineering provides retaining wall engineering across Melbourne, including site inspection, calculations and permit ready drawings for timber sleeper, concrete sleeper and steel post, block, and reinforced concrete walls.

The Permit Process for a Retaining Wall

The building surveyor is appointed by the owner and can be a private surveyor or the council's municipal building surveyor. Their role is to assess the application, issue the permit and oversee the inspections.

Planning Permits and Overlays

A planning permit is a separate approval under the local planning scheme. It may be needed for earthworks on sites affected by an Erosion Management Overlay, Land Subject to Inundation Overlay, Significant Landscape Overlay or Heritage Overlay, or in Green Wedge and rural zones. Check the planning controls for the property on the Victorian Planning Portal or with the council's planning department before assuming only a building permit is needed. Works near waterways or Melbourne Water assets may also need Melbourne Water's consent.

Frequently Asked Questions

Can I build a retaining wall without a permit in Victoria?

Yes, but only if the wall is less than 1 metre high, is not associated with other building work, and does not protect adjoining property. If any one of those conditions is not met, a building permit is required. Confirm with a registered building surveyor before starting.

What height retaining wall needs a permit in Victoria?

Any retaining wall 1 metre or higher needs a building permit. Walls under 1 metre also need a permit if they are part of other building work or hold up a neighbour's land or structures. Height is taken at the highest point of retained ground.

Do I need a structural engineer for a retaining wall in Victoria?

For a wall that needs a building permit, the building surveyor will almost always require structural drawings and calculations from a registered engineer. For exempt walls, engineering is not mandatory but is recommended for walls near 1 metre, near boundaries or buildings, or in reactive clay.

Does a retaining wall on the boundary need a permit?

Usually yes. A boundary wall that retains the neighbour's ground is protecting adjoining property, so the exemption does not apply. A fence on top of the wall adds surcharge and may trigger a siting assessment, and walls within an easement need the easement authority's consent.

How much does retaining wall engineering cost in Melbourne?

The engineering fee depends on the wall height and length, soil conditions, surcharge, drainage and the documentation required for the permit. Principal Built Engineering provides a fixed-fee proposal after reviewing the site details. The structural engineer costs Melbourne page explains what drives engineering fees.

For retaining wall engineering in Melbourne, get in touch with Principal Built Engineering to discuss your wall and receive a fee proposal.