Retaining walls look simple, but they hold back a surprising amount of weight, especially when the soil behind them is wet. That’s why NSW has clear rules about which walls you can build without approval, and why the bigger ones need proper engineering.
General information, based on the NSW State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, clauses 2.29–2.30. Always confirm for your property.
The short answer
In NSW, a retaining wall can usually be built without council approval if it is 600 mm high or less and at least 1 m from each boundary, and it meets the other exempt standards below. Higher walls, or walls closer to the boundary, generally need approval, and should be designed by an engineer.
The exempt development rules for retaining walls
Earthworks and retaining walls are exempt development only if they’re not on a heritage item, a flood control lot or in an environmentally sensitive area, and they meet all of these:
- Cut or fill no more than 600 mm below or above existing ground level.
- Located at least 1 m from each lot boundary.
- A retaining wall no more than 600 mm high, measured from its base to its top.
- At least 2 m (horizontally) from any other retaining wall on the site, so you can’t stack several small walls to make one big one.
- At least 1 m from any registered easement, sewer main or water main.
- Adequate drainage lines connected to your existing stormwater system.
- It must not redirect surface or ground water, or wash sediment onto a neighbour’s property.
- In a heritage conservation area, it must be in the rear yard.
- At least 40 m from a natural waterbody.
- Any imported fill must be clean natural material, not building waste.
When do you need an engineer?
As a rule of thumb, involve an engineer when:
- the wall is over 600 mm high
- it’s holding up a driveway, building, pool or another wall
- the ground is steep, wet or unstable
- it’s close to a boundary, easement or sewer line
Even where a small wall is exempt, it still has to be built to last. That means proper footings, the right post depth and spacing for sleeper walls, and drainage behind the wall.
Why drainage is the part that matters most
Most failed retaining walls we see didn’t fail because they were too thin. They failed because water had nowhere to go. Wet soil is heavy, and it pushes hard against the wall. A well-built wall has:
- Ag pipe (slotted drainage pipe) along the base behind the wall
- Drainage gravel behind the wall so water reaches the pipe
- Geotextile fabric to stop soil clogging the gravel
- a connection to your stormwater system, as the exempt rules require
Ask every builder how they’ll drain the wall. If the answer is vague, keep asking.
Which wall type?
- Concrete sleepers with steel posts. Strong, quick to install, and won’t rot. The most popular choice on Sydney slopes.
- Block walls (like split-face block). Clean, modern and can be rendered. See our split-face block garden box in Eastwood.
- Sandstone. A classic Sydney look for front gardens. See our sandstone front wall.
- Timber sleepers. A lower-cost option for small garden walls, but timber in the ground has a shorter life than concrete or stone.
Planning a wall?
We’ll look at the slope, the soil and the boundaries, tell you whether your wall is likely to be exempt, and show you the options. See our retaining wall service or call 0475 424 078.
Frequently asked questions
Can I build a retaining wall on the boundary without approval?
Under the exempt rules, the wall must be at least 1 m from each boundary. Boundary walls usually need approval, and your neighbour will be affected too.
Can I build two 600 mm walls to make a terrace?
Only if they’re at least 2 m apart horizontally. Stacked or closer walls act as one taller wall and need approval.
Do small garden bed walls count?
Low garden edging generally isn’t “retaining” much soil, but if it holds back a change in level, the same rules apply. When in doubt, check.
Source: NSW Legislation, State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, clauses 1.16 and 2.29–2.30 (version in force from 11 September 2026, accessed 29 September 2026). This article is general information only and is not legal advice. Rules can change, so check the current legislation or with your council before you build.