What size deck needs council approval?

No single size answers it, because the size is only one of the things that decide it. A deck’s approval turns on how high its floor stands above the ground, how much floor it has, whether it fixes to the house, how close it comes to a boundary and whether a roof goes over it. A small deck close to the ground can often go ahead without building approval where it meets every condition the state sets. A raised or large deck usually needs approval, and a deck with a roof over it is assessed like a patio.

How is the height read?

It is read where the floor stands highest above the ground, which is rarely at the step by the back door. On a sloping block a deck can sit low at the house and well up at the far end, and the far end is the one that counts. Height matters near the boundary too, since a raised deck close to a side fence can look straight into the neighbour’s yard, and in some places that brings a privacy question of its own.

What else decides it?

After the height, the floor area counts, and so does whether the deck is attached, because attachment changes how it is classified and what the certifier checks near the boundary. The lot adds its own questions. A deck over a sewer main needs the asset owner’s consent before the certifier’s, one over an easement needs its holder’s, a heritage or character overlay can bring a planning approval, and on land mapped bushfire prone the decking has to suit the lot’s bushfire attack level. The post on what can go ahead without approval covers the wider picture for backyard work.

Who decides?

The certifier, or the council where it assesses building work, decides whether the deck needs building approval and gives it when it does. The council decides any planning question an overlay or the privacy rules raise. If the deck will carry a spa or a roof later, say so at the start, because both change the assessment.

What goes on the site plan?

the deck at its real size, with the stairs where they land
its distance to each boundary, and to the house if it stands apart
the floor height above the ground where it is highest
easements and nearby mains, a north point and a scale

Reading it for your own lot

RapidSiteplan reads the lot from its address in a minute: the boundaries, the house traced from the aerial photo, the overlays, and the easements and mains where they are published. Place the deck and the sheet dimensions its distance to every boundary, and the bushfire report comes with it when the lot is mapped bushfire prone. The patio and carport page covers work against the house, the post on attached patios explains why fixing to the house changes the answer, and the council pages for every state show what each council maps. Start with the address. The post on council approval for a pergola covers why the roof changes the answer. The post on complying development certificates covers who issues one and what goes with it.

Common questions

What size deck needs council approval? No single size decides it. The height of the floor above the ground at its highest point, the floor area, whether the deck fixes to the house and how close it comes to a boundary decide whether it needs building approval. A roof over the deck changes the answer again.