Can I build a retaining wall on the boundary?

Often yes. A retaining wall can sit on or close to the boundary in most places, as long as the wall, its footing and its drainage stay wholly inside your lot. Whether it needs building approval depends on its height and on what it holds up, and whether its position needs the council’s agreement depends on the planning rules for the lot. The neighbour’s land, their fence and where the water goes decide the rest.

Where exactly is the boundary?

The old fence is not always on the line. Before a wall goes in on the boundary, find the true line from the survey plan, and where it matters, ask a surveyor to peg it. The post on finding your property boundaries explains how to read the line.

When does the wall need approval?

Every state lets a low wall be built without a building application when it stays within the limits the state sets, and those limits turn on the wall’s height, its distance from buildings and boundaries, and whether it holds up a load such as a driveway, a fence or a slab. A taller wall, or one carrying a load close to the line, usually needs building approval and an engineer’s design. In Queensland a certifier gives that approval, and in New South Wales a wall outside the exempt standards goes through complying development or a development application. The post on retaining wall heights covers the height question.

What about the retaining wall neighbour?

A wall on the line changes the ground on both sides. Fill behind it can push on the neighbour’s land and footings, and a cut can take away the support their land relies on. Talk to them before you start, agree in writing on any access, on the fence and on what happens to it during the works, and keep their side clear of your spoil and water.

Where does the water go?

Behind every retaining wall sits water. The drain behind the wall has to discharge onto your own lot or into your stormwater line, never onto the neighbour’s land.

Does a fence on top change anything?

Yes. A fence on a retaining wall adds height and wind load, which can bring the pair inside an approval even when each alone sits within the limits. The post on a fence on a retaining wall covers how the two are read together.

Reading it for your own lot

RapidSiteplan reads the council and building rules for your lot from its address, checks the design against them as you place it, lets you edit it as often as you like, and prints the site plan. Site plans and assessments in minutes. Draw the wall along the line and the plan shows its height, the high side and its distance to each boundary.

Search your address, or see what the plan shows for a retaining wall. Each council page, such as Ipswich, lists what we hold for that council, and site plans by council covers the rest of Australia.

Common questions

Can I build a retaining wall on the boundary? Often yes, as long as the whole wall, its footing and its drainage stay inside your lot. Its height and what it holds up decide whether it needs building approval, and the council’s rules decide whether its position needs a planning approval.

How close to the boundary can I build a retaining wall? It depends on the wall’s height, what sits near it and the rules where you live. A low wall can often sit near the line, while a taller one, or one holding up a driveway, fence or building, usually needs approval and an engineer’s design.

Do I need to tell my retaining wall neighbour before I build? Talking to the neighbour first is wise, and you need their agreement for any work on their land, such as digging for the footing or moving their fence. In some places the council also asks for their comments on a tall wall near the line.