It is the question that stops most retaining wall projects before they start, and the answer people usually repeat- that anything under a metre is fine- is only half true. The height rule is real, but it comes with conditions that catch a lot of homeowners out.
Here is what the Victorian regulations actually say, what the exemption covers, and the situations where a wall well under a metre still needs a permit. Worth reading before you order retaining wall products, because discovering you need engineering after the sleepers arrive is an expensive way to learn it.
The short answer
In Victoria, retaining walls are governed by the Building Act 1993 and the Building Regulations 2018. A building permit is generally required once a wall reaches one metre in height. Below that, an exemption exists under Schedule 3 of the regulations, but it is narrower than most people assume.
The exemption broadly applies to a wall that is under one metre, stands on its own, does not carry any load beyond the soil behind it, and does not protect or support an adjoining property. Fail any one of those conditions and the exemption stops applying, no matter how low the wall is.
When a permit is required regardless of height
These are the triggers that surprise people. A wall of 600mm can need a permit just as readily as one of 1.5 metres if any of the following apply.
| Trigger | What it means in practice |
| Supports a surcharge load | The wall holds back soil that carries a driveway, a paved area, a pool, a shed or any structure within the zone of influence behind it. |
| Protects or supports adjoining land | The wall retains soil belonging to, or supporting, a neighbouring property. Height is not the deciding factor here. |
| Part of other building work | The wall forms part of a wider project such as a new build, an extension or a pool installation covered by its own permit. |
| Close to a boundary | Excavation near a boundary can undermine a neighbour’s footing or fence. A protection work notice may need to be served on the adjoining owner. |
| Part of a tiered system | Two walls each under a metre are not automatically exempt. Where the tiers are close enough to act as one structure, the combined retained height is what counts. |
The tiered wall trap
This one deserves its own section because it is the most common attempt to work around the rules, and it does not work.
Splitting a 1.6 metre level change into two 800mm walls does not create two exempt walls. Where the tiers sit close enough together that they behave structurally as a single system, they are assessed on their combined retained height. The separation distance that determines whether tiers are treated individually or together is a judgement for your building surveyor, not something to estimate from a landscaping video.
Built the wrong way, a tiered system also loads the lower wall with the weight of the upper one, which is a structural problem long before it is a compliance problem.
How the height is measured
The one metre threshold is measured as retained height, from the lower ground level at the base of the wall to the top of the retained soil. It is not the visible portion of the wall after backfilling, and it is not the sleeper count.
This matters on cut and fill blocks, which describe most new estates across Melton, Aintree and the western growth corridor. A wall that looks modest from the high side may be retaining well over a metre when measured properly from the low side.
Building permit and planning permit are not the same thing
Two separate approvals, and a project can need one, both or neither.
- A building permit deals with structural safety and is issued by a registered building surveyor, either private or through council.
- A planning permit deals with land use and amenity, and comes from council under the local planning scheme. It can be triggered by heritage overlays, sensitive zones, earthworks volume, walls facing a street, or impact on overland flow paths.
Councils across the west apply the planning scheme differently, so Melton, Wyndham and Brimbank will not necessarily give you the same answer for an identical wall. Ask each one directly rather than assuming a neighbour’s experience transfers.
Engineering: required more often than permits are
A permit and an engineering design are separate questions. AS 4678, the Australian Standard for earth retaining structures, is the reference point for design, and engineering input is commonly required well below the one metre permit threshold.
On the reactive clay that dominates Melbourne’s western suburbs, engineering advice is worth having on any wall approaching a metre even where no permit is triggered. Soil that swells and shrinks through the seasons puts loads on a wall that a standard build detail does not always account for, which is one reason galvanised steel post systems are specified so often across the corridor.
Drainage is a compliance issue, not an optional extra
Where a permit applies, a building surveyor will expect to see drainage detailed properly: agricultural drain at the base behind the wall graded to a lawful discharge point, free-draining aggregate backfill, and weep holes where the wall face is solid.
There is a second exposure here that has nothing to do with the Building Regulations. A wall that redirects water onto a neighbouring property can create a separate legal problem regardless of whether the wall itself was permitted. Getting the drainage right protects the wall and the relationship.
What happens if you build without a permit
Building surveyors and councils can issue orders requiring non-compliant work to be rectified or removed, at the owner’s cost. That can mean demolishing a finished wall and rebuilding it correctly, along with everything landscaped behind it.
There is a quieter consequence too. Unpermitted structural work tends to surface during a sale, and an unresolved compliance issue on a retaining wall is exactly the kind of thing that delays a settlement. The absence of a permit also does not remove liability if the wall fails and damages a neighbour’s property.
A practical sequence before you order
- Measure the retained height from the low side, not the high side.
- Identify anything sitting behind the wall: driveway, shed, pool, paving, structure.
- Check the distance to the nearest boundary.
- If the design is tiered, treat the combined height as the working figure until a surveyor tells you otherwise.
- Call your council or a registered building surveyor with those four answers ready. It is a short conversation when you have them.
- Order materials once the answer is confirmed, not before.
Frequently asked questions
Is a garden bed edge classed as a retaining wall?
If it holds back a change in ground level, it is retaining soil regardless of what it is called. Low decorative edging that sits on level ground is not. The test is whether soil on one side is higher than the other, not the material or the description.
Who applies for the building permit, me or my builder?
The owner is ultimately responsible for ensuring work is permitted, though a builder or building surveyor usually manages the application. If you are building it yourself, the responsibility sits with you.
Does the neighbour have to agree to a retaining wall on the boundary?
Where the work could affect their land, a protection work notice may need to be served, and the adjoining owner has a formal opportunity to respond. Beyond the legal process, a conversation early is worth more than a notice later.
Do I need a permit to replace an existing retaining wall?
Replacement is new building work, and the same triggers apply. An old wall that predates current regulations does not carry an exemption forward to its replacement.
How long does a retaining wall permit take in Victoria?
It varies by surveyor and by how complete the documentation is. Engineering drawings, a site plan and material specifications submitted together move faster than a staged application. Allow for it in the project timeline rather than treating it as a formality at the end.
Get the materials right once you have the answer
Prime Green Fencing supplies concrete sleepers, galvanised steel posts, treated pine sleepers and full drainage kits from our Truganina yard. Come to us with your engineering specification or your measurements and we will make sure what you take away matches what the wall actually needs.
Call 0452 113 113 or visit 26 Apex Dr, Truganina VIC 3029. We deliver across Melton, Rockbank, Deanside, Tarneit, Werribee, Point Cook and the wider western suburbs.