Retaining walls in Mickleham

A retaining wall holds back soil where one part of a lot sits higher than another, and in Mickleham estates they are most common along side and rear boundaries where the civil works left a step between neighbours. Melbourne price guides list timber sleeper walls at $135 to $450 per sqm of wall face and concrete sleeper walls at $225 to $630 per sqm. The site you are reading takes enquiries only; the wall is designed, priced and built by an independent provider, who must hold the right registration where the law requires one.

When does a retaining wall need a building permit?

Under the Building and Plumbing Commission’s landscaping guidance, a retaining wall needs a building permit if either or both of these apply:

• the wall is 1 m or taller
• the wall sits on a lot boundary, or close to one, where it could damage the neighbouring property

Small walls that meet neither test may not need a permit. Hume City Council’s fencing and retaining wall page adds that if the wall is part of a larger project with a building permit, it must be included in that permit. When in doubt, ask a registered building surveyor or the council before any digging starts.

Who can build it?

In the Commission’s view a retaining structure is domestic building work. Once the contract price passes the threshold on its landscaping page, only an appropriately registered building practitioner can build the wall. The class written for this job is Domestic Builder (Limited to the construction of retaining walls). The Commission also lists a broader class for yard work, Domestic Builder (Limited to the construction of structural landscaping). Before a Mickleham boundary wall goes in, search the provider’s name, business name or registration number on the BPC practitioner register.

Taller or heavily loaded walls need an engineer. AS 4678 is the Australian Standard that sets design criteria for earth-retaining structures, for use by engineers and designers.

Comparing wall types

Wall type	Typical use	Strengths	Limits
Treated pine or hardwood sleepers with steel or timber posts	Low garden walls, back fences	Cheapest, quick to build	Timber rots over time, especially where wet soil sits against it
Concrete sleepers between steel H posts	Boundary walls on estate lots	Long life, slim, common for boundary steps	Post footings and steel need correct sizing
Segmental concrete blocks	Curved walls, front yards, terraces	Neat finish, many colours	Taller walls need geogrid reinforcement and engineering
Rock or boulder walls	Larger sloping blocks, rural edges	Natural look	Needs machine access and space

The Melbourne price guide used on this site does not list segmental block walls, so price them from a quote based on the wall height, the reinforcement the design calls for and the block range you choose.

Signs a wall is failing

• The wall leaning out at the top or bulging in the middle.
• Sleepers bowing between posts, or posts rotating.
• Soil washing out at the base or between sleepers.
• Water pooling behind the wall after rain.
• Cracks in paving or a fence line running parallel to the wall.

A leaning wall on a boundary is a matter for both neighbours. The Fences Act 1968 covers dividing fences, and a fence sitting on top of a failing wall often needs both dealt with together. Talk to your neighbour before work starts.

What the provider will check before quoting

• Retained height at the highest point, wall length and the soil level on each side.
• Whether the wall is on or near a boundary and what sits above it (a fence, a driveway, a house).
• Ground conditions. Clay that swells when wet and shrinks when dry adds load to a wall, and the soil report prepared for your house slab is a useful starting point.
• Where the drainage behind the wall will discharge.
• Access for an auger or excavator to dig post holes.
• Underground services, through a Before You Dig Australia enquiry.

What the work involves

Set out and level the line, dig post holes or a footing, set posts in concrete, then build up the sleepers or blocks. Behind the wall the provider lays a slotted drainage pipe in clean gravel, wrapped in geotextile fabric where needed, and connects it to a legal discharge point. The space is then backfilled and compacted in layers.

What a careful provider will refuse to do

• Build a wall 1 m or higher, or one that could affect a neighbour’s land, without a permit.
• Skip drainage behind the wall, which is the most common reason sleeper walls lean.
• Stack sleepers higher than the post size and spacing allow.
• Backfill with builder’s rubble.
• Discharge wall drainage onto a neighbour’s lot.

Local angle

Estate lots in Mickleham and Kalkallo are often benched, so neighbouring yards sit at different heights and the wall goes on the boundary. Some estate guidelines limit visible wall height at the front; Merrifield’s design guidelines keep visible front retaining walls and pillars under 1.0 m. On the larger rural residential blocks around Mt Ridley and Greenvale, walls are more often used to create flat terraces on a slope.

Related guides

Walls go in before paving and paths and lawn. See new home landscaping for the order of works and the landscaping cost guide for how walls affect the total. The Mickleham area page has estate notes.

What to do next

Measure the length and the highest retained height, note whether the wall is on a boundary, and photograph both sides. Then send the retaining wall details through the quote form so a provider can tell you whether a permit and engineering are likely.

Send a job enquiry