"Do I need approval for this?" is one of the first questions almost every Canberra homeowner asks us, and it's a fair one — the exempt development rules, height triggers and setback requirements aren't exactly common knowledge. Here's what actually determines whether your deck needs a Development Application in the ACT, how long that process realistically takes, and what happens if a deck goes up without it.
When a Deck Is Exempt From Approval (Height, Size, Position Rules)
As a general rule, decks under 1 metre high and more than 900mm from a boundary usually don't need council approval in the ACT. That height is measured from the deck's finished surface down to the ground at its lowest point around the perimeter — not just at the point closest to the house — which matters more than people expect on a sloping block. Stay under both thresholds and your deck typically falls into exempt development territory.
When You Need a Development Application or Building Approval
Go higher than 1 metre or closer than 900mm to a boundary and you're generally into Development Application territory, along with building approval and often an engineering certificate for the structure itself. Those are two related but separate processes — a DA deals with whether the deck can go where you want it, while building approval deals with whether it's structurally sound. A handful of other factors can also change what's required on a specific block, from heritage overlays to covenants on newer estates, so it's worth confirming your exact requirements with ACT Planning or a licensed certifier before finalising a design, rather than assuming the general rule covers every situation.
Timeframes: How Long Approval Realistically Takes
Once a design needs a Development Application, expect the paperwork and approval process to take roughly 2–4 weeks, depending on how busy council is at the time and whether any additional information gets requested along the way. It's worth building that timeframe into your overall project schedule from the start rather than assuming construction can begin the moment your design is finalised — approval genuinely needs to be locked in first.
What Happens If You Build Without Approval
Building without approval when it was required can mean a stop-work notice mid-project, or being asked to apply for approval retrospectively — which isn't guaranteed to succeed and can mean modifying or even removing a structure that's already built. It also tends to surface at the worst possible time: during a future sale, when a buyer's building inspector flags an unapproved structure and either delays settlement or knocks value off an offer. It's a far cheaper problem to sort out before the first post goes in than after the deck is finished.
How We Handle the Paperwork for You
Working out whether a design is exempt or needs a DA happens as part of our initial consultation, before we quote the job — not as a surprise partway through. Where approval is needed, we prepare and lodge the development application, arrange engineering certificates, and manage building permits, so you're not learning ACT planning requirements from scratch on your own project. It's part of our custom deck design and build process. If you're weighing up materials as well as approval requirements, our timber decking page covers the species and design options we build across Canberra.
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