A low deck off the back door can sometimes be built without approval. Raise it, make it bigger or put a roof over it, and it needs one. Here is where the lines are in Queensland, and the other rules that come with a deck once it is off the ground.
The exemption is small
Under the Building Regulation 2021, a deck is exempt from building approval only while all of these are true:
- It has no roof
- It is no more than 10 m² in area
- Its floor is no more than 1 m above the ground
Go past any one of those and the deck needs a building approval from a certifier, with engineering. A typical family deck of 4 × 5 m is already twice the area limit. The siting rules, such as boundary setbacks, still apply to an exempt deck.
A roof changes everything
A roofed deck is never exempt, whatever its size or height. Ipswich City Council says it plainly in its building guidelines: once a deck is roofed, or its floor is more than 1 m above natural ground, it needs a building approval. The deck and its roof are approved together, which is one reason we prefer to build them together.
Balustrades
Once a deck is high enough that someone could fall 1 m or more, it needs a balustrade under the National Construction Code. The main requirements, which your certifier checks, are:
- At least 1 m high above the deck floor, and 865 mm above the line of the stair treads.
- No gap that a 125 mm sphere can pass through, between balusters or under the bottom rail.
- Where the floor is more than 4 m above the ground below, no horizontal or climbable parts between 150 mm and 760 mm above the floor, so children cannot climb it.
Glass, aluminium and steel balustrades can all meet these. Wire balustrades need careful tensioning to keep the gaps under 125 mm, which is why many certifiers look closely at them.
Stairs
Stairs to a deck have their own rules for riser and tread size, handrails and landings. A long run of stairs from a high deck often needs a landing part way. We draw the stairs as part of the deck so the certifier sees the whole thing at once.
Privacy screens
- Gold Coast: where a raised deck looks into the neighbour’s private open space, it needs a privacy screen of at least 50% transparency.
- Brisbane small lots: a privacy screen can have no more than 25% openings, each no more than 50 mm, and sits 0.3 m off the wall face.
- Elsewhere, screening is usually about your own comfort, but a raised deck close to a boundary can still need it to meet the siting rules.
Decks over a sewer
Urban Utilities, which owns the sewer in Brisbane, Ipswich and the Scenic Rim, asks that a deck more than 1.2 m high over its sewer have a removable section of about 1.5 × 1.5 m for access to the connection. In every council, footings keep clear of the main, and manholes must stay open and reachable.
Height and roofs in the Redlands
Redland City Council caps building height at 8.5 m on most sloping lots, but lets a roof over a deck reach 10 m when it covers no more than 10 m², is the only such roof and is not walled in. That helps on a two-storey home with an upper deck.
Frames: timber or steel
A timber deck frame is sized from Timber Queensland’s span tables for the timber grade and spacing. A steel frame is engineered for the job and does not rot or get termites, which suits decks close to the ground or on a high, exposed site. Either way the certifier sees the design before we build.
Our advice
- If you might want a roof later, design the deck for it now, with posts and footings that can carry it.
- Measure the height from the ground at the lowest point, not at the back door.
- Choose the balustrade before the build: it changes the posts and fixings.
- Let us handle the approval. We draw the deck, stairs, balustrade and roof together and lodge them as one.