Retaining walls are a common feature in sloping blocks and landscaped yards, but many homeowners underestimate how tightly they are regulated. While a low garden wall may seem straightforward, retaining walls in Mornington Peninsula often fall under strict council and building rules due to soil conditions, drainage risks and proximity to neighbouring properties. At JBS Excavation & Retaining Walls, we assist homeowners who are unsure whether their planned wall requires approval. And just as often, those who only realise after construction has begun or finished. Understanding permit requirements before construction begins can save significant time, cost and legal stress.
Below is a clear guide to when permits are required, what factors trigger council involvement and how to protect yourself from costly compliance issues.
Not all retaining walls are treated equally under building regulations. Whether a permit is required depends on factors such as height, location, structural purpose and site conditions.
Councils assess retaining walls not just as landscaping features but as structural elements that interact with soil pressure, drainage and neighbouring land. One of the most common and costly mistakes homeowners make is failing to recognise when a wall has crossed from “minor landscaping” into a regulated structure.
Height is often the first factor councils look at, but it is also one of the most misunderstood. While many believe anything under one metre is automatically exempt, this is not always true. The reason height matters is simple: as a wall gets taller, the pressure exerted by retained soil increases exponentially. This raises the risk of failure, collapse or downstream damage if the wall is not properly engineered and drained. In most cases:
Retaining walls built close to or directly on property boundaries face additional scrutiny. Because boundary walls affect soil stability, drainage and load distribution on neighbouring properties, they are one of the most frequent sources of disputes and are subject to stricter council approval standards. Extra requirements are commonly triggered when:
In these cases, councils may require:
A retaining wall that supports more than just garden soil is almost always considered a structural element. The moment a wall carries additional loads, permit requirements typically apply regardless of height. These loads increase the forces acting on the wall. Councils require engineering input to ensure the wall can safely withstand vertical and lateral pressure. Common examples include retaining walls that support:
Even a relatively low retaining wall can require approval if site conditions are challenging. Poor drainage and unstable soils are major contributors to wall failure, which is why councils often require engineered designs in certain areas. Engineering drawings demonstrate how drainage, footings and reinforcement will manage long-term soil pressure and stability. Permit triggers related to site conditions include:
Many homeowners assume permit issues are only a concern during construction. In reality, non-compliant retaining walls are often discovered long after the work is finished, most commonly during a sale, refinance, insurance assessment or following a neighbour complaint.
Unfortunately, councils rarely accept a lack of awareness as a defence. Once an unapproved wall is identified, enforcement action can begin regardless of when it was built. In many cases, the financial and legal costs of rectification far exceed the effort of securing approvals upfront.
When a council becomes aware of an unapproved retaining wall, the response is usually formal and time-sensitive. Local authorities have a responsibility to manage structural safety, drainage impacts and land stability, which gives them broad powers to enforce compliance. Even if the wall appears structurally sound, council action is based on approval status, not appearance. Possible outcomes are:
One of the most overlooked consequences of building without permits is how it affects insurance and legal liability. Many only discover the issue after a retaining wall fails or causes damage, at which point it may be too late to correct. Insurers commonly exclude cover for damage linked to non-compliant or unapproved structures, leaving homeowners fully exposed. Risks could be:
Preventing permit issues starts well before excavation begins. Understanding your site conditions, council rules and the structural role of your retaining wall allows you to identify approval requirements early, when they are easiest to address. Many compliance problems stem from assumptions, such as believing a wall is “only landscaping” or assuming height alone determines approval needs. Take note of these steps:
While small, low-risk retaining walls may not require multiple consultants, many projects cross into territory where expert involvement is essential. The challenge is knowing where that line sits. Engaging the right professionals early helps clarify approval requirements, ensures accurate documentation and reduces the risk of redesign or rework. You should involve professionals when:
Retaining walls may appear simple on the surface, but the rules surrounding permits, approvals and engineering are often far more complex than homeowners expect. Various factors determine whether council approval is required. Taking the time to confirm these requirements before construction begins helps avoid fines, disputes and costly rectification later. At JBS Excavation & Retaining Walls, we believe the best retaining wall projects are the ones that never become compliance problems. Our team works with homeowners across the Mornington Peninsula to assess site conditions, explain permit requirements clearly and deliver retaining walls that meet council standards from the outset. If you’re planning a retaining wall and aren’t sure whether approvals, engineering or surveys are required, speaking with a specialist early can save you time and expense.
