Do I Need Approval for a Deck in NSW?

This is the question we field most often, and the answer turns almost entirely on height.

Exempt development

A deck can often be built without any approval if it meets all of the relevant criteria. Broadly, that means it is:

• Not more than 600mm above ground level
• Not more than 25 square metres in area
• Set back at least 900mm from each boundary
• Not on heritage-listed land or in a heritage conservation area
• Not in an environmentally sensitive area
• Behind the building line

Every one of those has to be satisfied, not most of them. A 30 square metre deck at 400mm high is not exempt. A 20 square metre deck at 700mm high is not exempt.

Complying development

Step outside the exempt limits and you generally need a Complying Development Certificate. That is a certifier assessment against a defined set of standards, usually two to four weeks and a few thousand dollars.

CDC allows a considerably larger and higher deck, with requirements around setbacks, privacy screening where you overlook a neighbour, and structural adequacy.

Development Application

You are into DA territory if the land is heritage listed, flood affected, in a bushfire zone above a certain level, or if the design exceeds complying development standards.

The 600mm line and why it matters

At 600mm, two things change. Fall protection becomes a consideration, and the structure moves from being effectively a platform to being a building element that needs engineering.

Above one metre, a compliant balustrade is required. That means a minimum height of one metre, and gaps that will not allow a 125mm sphere to pass, plus a non-climbable zone. These are not optional and a certifier will check them.

What people get wrong

Measuring from the wrong point. Height is measured to existing ground level directly below, at the highest point of the deck. On a sloping block the low corner is what counts.

Forgetting the roof. Adding a roof over the deck changes the assessment. A roofed structure has different criteria to an open deck.

Building to the boundary. The 900mm setback is common and frequently overlooked on narrow blocks.

Assuming the neighbour’s deck sets a precedent. It may have been approved under older rules, or not approved at all.

Why it matters later

Unapproved structures show up in two places: when you sell and a building inspection flags them, and when you claim on insurance after a storm. Neither is a good time to discover the problem.

Retrospective approval is possible but more expensive and not guaranteed, and if the structure does not comply you may be required to remove it.

Our approach

We assess the approval pathway before we quote, so the price you get already reflects the certification you actually need. If your design is marginally over an exempt limit, we will tell you, because pulling it in slightly is often far cheaper than the certification it triggers.

We build decks throughout Newcastle, Lake Macquarie and Port Stephens.