DA vs CDC for Retaining Walls

Overview

"DA" and "CDC" are New South Wales planning terms. A Development Application (DA) is a merit assessment lodged with your local council; a Complying Development Certificate (CDC) is a fast-tracked, combined planning and construction approval issued by a council or a private certifier. For a retaining wall, which one applies is not a preference — it is decided by whether the wall can meet every standard in the code. Miss one, and the CDC is off the table.

In other states the equivalent is a building permit or development approval — see our building permits guide for the process outside NSW.

The Three Pathways

NSW retaining walls fall into one of three approval tracks under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 — the "Codes SEPP":

• Exempt development — small, low-risk walls that need no approval at all.
• Complying development (CDC) — walls that meet every prescribed standard and can be certified quickly.
• Development Application (DA) — anything that does not fit the first two, assessed on its merits by council.

Height, distance to the boundary, and site overlays decide which track you are on.

Exempt: Under 600mm

A wall is generally exempt — no DA, no CDC — where it is no more than 600mm high, at least 1m from any boundary, separated from other retaining walls by 2m, does not redirect water onto a neighbour, and drains to stormwater. Clear 600mm and you move into CDC or DA territory.

When CDC Applies

Above 600mm, earthworks support may proceed as complying development under Schedule 9 of the Codes SEPP, provided the wall meets every standard. The key conditions are:

• A professional engineer certifies the wall as structurally sound, including its ability to resist lateral soil load.
• It does not redirect surface or ground water, or push sediment, onto adjoining land.
• It has adequate drainage connected to the site's stormwater system.
• Its total height does not exceed the height of the excavation or fill it retains.

The catch is that last point: these provisions are written as support for earthworks associated with development under the code, so they suit a wall accompanying a dwelling or extension far better than a freestanding wall lodged on its own. Where it applies, a CDC can issue in as little as 20 days.

When a DA Is Required

A DA is needed wherever the wall cannot satisfy every CDC standard, or sits on excluded land. As a rule of thumb, freestanding walls over about 1.5m, walls near a boundary, and walls on constrained sites almost always need one. Unlike a CDC, it is a discretionary, merit-based assessment — council weighs impacts on neighbours and drainage and can impose conditions or refuse. A DA is planning consent only; you still need a Construction Certificate before work starts. Expect roughly 6–10 weeks against 20 days for a clean CDC.

The Exclusions That Force a DA

Even a modest wall is pushed onto the DA path if the site carries certain constraints:

• Heritage — listed items and conservation areas.
• Bushfire and flood — permitted in some cases, but subject to extra code requirements.
• Boundary position — building on or close to a boundary raises neighbour-consent and easement issues regardless of height.
• Covenants — a CDC does not override a private covenant on the title.

Working Out Which Applies

Three questions settle it before any design work begins:

1. How high is the wall? Under 600mm and clear of the boundary, likely exempt.
2. How close to the boundary, and what does it retain? This sets whether a CDC's standards can be met.
3. What overlays sit on the land? A Section 10.7 planning certificate reveals heritage, bushfire, flood and zoning — any of which can force a DA.

Because the CDC pathway hinges on an engineer certifying the wall against lateral soil load, getting the engineering done early is often what keeps a project on the faster CDC track. Talk to us about certification for your wall.

Frequently Asked Questions