Platform framing: the stacked-storey system behind most Australian homes

TL;DR

Platform framing is the construction method where each floor level is built as a complete, sheeted platform before the walls above it go up. It is the standard system for light timber and steel framing in Australia: roughly 80% of detached dwellings are timber-framed this way (verified 2026-05-24, WoodSolutions). It replaced balloon framing (continuous studs running the full height of the building) decades ago, mainly for fire safety and ease of handling. The framing rules for the method sit in AS 1684, the deemed-to-satisfy pathway under NCC 2022 Volume Two clause H1D6(4) for Class 1 and 10 buildings. Understand platform framing as the system; the members that make it up (plates, studs, noggings, lintels) are covered in timber framing basics.

Body

What platform framing is

In platform framing, the building goes up one storey at a time, and each storey is a working platform for the next. The sequence is stacked:

The ground floor is framed (bearers and joists, or a concrete slab) and sheeted, creating a flat deck.
Wall frames for that level are built, stood up, and braced on the deck.
The next floor or ceiling frame is built on top of those walls, forming the platform for the level above.
The process repeats up to the roof structure.

Each platform is structurally complete before the next is started. That is the defining feature: the walls of one level do not continue past the floor of the next. Every level is “reset” at the floor line.

Platform vs balloon framing

The method platform framing replaced is balloon framing, where the wall studs ran continuously from the bottom plate at the floor all the way to the roof, with the intermediate floors hung off the sides of those long studs.

Balloon framing was superseded in Australia by platform framing, mainly for practicality and safety: shorter, easier-to-handle timber lengths, and a much lower fire risk. In a balloon frame the wall cavities run uninterrupted from floor to roof, so a fire in the wall has a clear vertical chimney; platform framing breaks that path at every floor (verified 2026-05-24, WoodSolutions Lightweight Timber Framing Guide).

Feature	Platform framing	Balloon framing
Stud length	One storey at a time	Full building height
Floor support	Walls below carry the platform above	Floors hung off continuous studs
Wall cavity fire path	Broken at each floor line	Continuous floor to roof
Timber handling	Short, standard lengths	Long, heavy members
Australian status	Standard practice	Superseded (rare)

Why it became standard in Australia

Platform framing suited Australia’s post-war housing boom, where large volumes of detached dwellings had to go up fast. Local mills standardised softwood stud and joist sizes (90x35 mm, 90x45 mm), and the design rules were formalised nationally when AS 1684 was first published in 1975 (verified 2026-05-24, WoodSolutions Lightweight Timber Framing Guide). The method works the same way in light steel framing (see steel framing basics); the sequence is identical, only the members and connections change.

Where the rules sit

For timber, the framing of a platform-framed house is designed and built to AS 1684.2:2021 (non-cyclonic) or AS 1684.3:2021 (cyclonic). These are the deemed-to-satisfy (DTS) pathways under NCC 2022 Volume Two clause H1D6(4) for Class 1 and 10 buildings (verified 2026-05-10, ABCB NCC 2022 Part H1). The span tables cover the method within set scope limits:

Limit	Value
Maximum storeys of timber framing	2
Maximum building width	16,000 mm
Maximum eave height	6,000 mm
Maximum roof pitch	35 degrees

Outside those limits, the frame falls to AS 1720.1 and a structural engineer (verified 2026-05-10, ABCB NCC 2022 Part H1).

The tie-down chain

Because each storey sits on the one below, the tie-down path for wind uplift has to run continuously down through every platform: roof to top plate, stud to plate, plate to floor, floor to wall below, and finally to the footing. Platform framing makes this a series of discrete links rather than one continuous member, so each junction has to be fixed per the AS 1684 tie-down schedule. A broken link at any platform negates the uplift resistance of everything above it.

What can go wrong

Stud walls erected before the platform is braced. Wall frames stood up on a deck that has no temporary or permanent bracing can rack or blow over before fixing. Brace before load.
Tie-down chain broken at a floor line. The most platform-specific failure: the roof and upper walls are strapped, but the connection from the upper platform down to the level below (or the bottom plate to the slab) is missed. The chain only works if every link is in.
Out-of-level platform. If a floor platform is built out of level, every wall and the platform above inherit the error. Check and correct level at each platform before framing the next.
Wrong sequence with services. Running the next platform before rough-in is complete on the level below traps services trades and forces cutting into finished framing (outside AS 1684 notching limits).

References

WoodSolutions, Timber framing (woodsolutions.com.au) (verified 2026-05-24)
WoodSolutions, Lightweight Timber Framing Guide, Forest and Wood Products Australia (woodsolutions.com.au) (verified 2026-05-24)
NCC 2022 Volume Two, Part H1 Structure, clause H1D6(4), Class 1 and 10 buildings (ABCB) (verified 2026-05-10)
AS 1684.2:2021 Amd 1:2024, Residential timber-framed construction, Part 2: Non-cyclonic areas (Standards Australia) (verified 2026-05-10)