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Layer 02 · Retaining walls

Retaining walls in Victoria: permits and who builds them

A retaining wall in Victoria needs a building permit when it is 1m or more in height, or when it is built on or near a site boundary where there is a risk of damage to the adjoining property; the Building and Plumbing Commission (BPC) says small walls outside those two cases may not need one. Retaining structures are generally domestic building work, so Victoria’s registration rule applies to who builds them.

General information, not legal or building advice. The official places to check are the Building and Plumbing Commission (BPC), your building surveyor and your local council.

Key plan, layer 02 The site plan with the retaining wall picked out in green, running across the contours of the slope.
Layer 02 is the thick line across the slope: the wall that holds the ground.

Definition and types

The BPC describes retaining walls as structures, usually of masonry, stone, timber, steel or concrete, that are not part of a building and are designed to stop soil subsiding onto land or property. The types, it says, include but are not limited to sleepers, sheet piling, gravity and cantilevered walls, and anchored, pre-cast and interlocking proprietary systems.

A retaining wall in sectionA cut through sloping ground. Higher ground on the left is held back by a vertical wall on a footing, with a drainage pipe behind the base of the wall. A dimension line beside the wall marks its height above the lower ground. Lower ground continues to the right, and a dash-dot line marks a site boundary a short distance from the wall, with the neighbouring land beyond it.
Illustration, not to scale: the two cases on the BPC’s list, a wall’s height and a site boundary close to it.

Building permits for retaining walls

The BPC’s landscaping page says a building permit is required for all retaining walls that are:

  • 1m or more in height, and/or
  • built on or close to a site boundary where there is a risk of damage to the adjoining property.

The BPC joins the two cases with “and/or”, so a wall in either case, or in both, is on the list. That is the whole list. Read it before you settle where a wall will go and how high it will stand.

Small walls that do not meet the definition may not need a building permit, in the BPC’s words. “May not” is not “do not”, so treat it as a question for a building surveyor.

A building permit is not the only approval in play. The BPC says that for any building work on your property you need to find out whether the project needs a planning permit, a building permit, or both.

The permit process

  1. Where a planning permit is needed, the local council issues it first; no building permit can be issued until then.
  2. You appoint a registered building surveyor and apply for the building permit through them. The BPC advises against signing any blank forms that authorise others to represent you.
  3. A surveyor may refuse a permit. You can then change the application so that it complies with the Regulations, or appeal the refusal to the Building Appeals Board.

Registration for retaining walls

Retaining structures are on the BPC’s list of landscaping work generally considered domestic building work. That brings in Victoria’s two-part rule:

In the Building and Plumbing Commission’s words: “You must engage an appropriately registered building practitioner when:”

Contract price“the contract price of the works is over $10,000”
and
Kind of work“the work is domestic building work.”

A wall inside a bigger job still counts. The BPC says that when even a small component of the landscaping is domestic building work, and the contract price is over $10,000, you need an appropriately registered building practitioner.

An illustration, not a ruling. Picture one contract to plant a new garden bed and build a sleeper retaining wall behind it, with a contract price over $10,000. Planting alone is not generally domestic building work, but the wall is a retaining structure, and the contract is no longer limited to planting. Read against the BPC’s rule, the contract would need an appropriately registered building practitioner.

Two registration classes are built around walls and the ground behind them.

The retaining walls class

Retaining walls for homes. The work includes site set-out and preparation, which can involve excavating and profiling soil levels, installing footings, and working out and installing suitable drainage.

The earthworks and excavation class

Earthworks and excavation for homes and associated class 10 buildings. The BPC says the work must be done safely and so that it avoids damaging neighbouring structures and property through soil collapsing or subsiding.

The BPC defines earthworks and excavation as removing earth, soil, rock and grass roots, to lines and levels set beforehand, to form a hole or trench for any of:

  • structural supports
  • the walls or floors of a building
  • structural landscaping work.

Classes with and without retaining walls

The broader structural landscaping class, in the BPC’s description, involves planning, designing, building and installing external landscape features, from fences and pergolas to retaining walls, decking and paving. It takes in retaining walls of any material that are not part of a building, among its other features. Two other classes leave walls out. The non-habitable structures class excludes retaining walls that are not part of the structure itself, and the swimming pools and spas class excludes the construction of retaining walls. Those are selections from longer lists, printed in full on Layer 03 and Layer 04.

A pool builder digging into a slope, then, may not be the right registration for the wall that holds the slope back. Ask which class each trade on your plan holds, and match it to the work in front of them.

Other layers of the plan