Stair Winders & Landings (NCC 2025)

The requirement

Turning a stair is where a lot of good work goes wrong. You’ve got two ways to do it: a landing — a flat platform you step onto mid-flight — or winders, the pie-shaped turning treads that fan around a corner. The rule book (NCC 2025, Housing Provisions Part 11.2) sets out how to do both safely.

Winders and the walking line. A winder is a tapered tread — wide on the outside of the turn, pinched to almost nothing on the inside. Its going (the depth you actually step onto) changes as you move across it, so the code says to measure it along a walking line — the path a person’s feet really take round the bend:

Stair type	Where the walking line sits
1 m wide or less	Down the middle
Wider than 1 m	400 mm in from each side
Spiral / circular	0.7 of the width out from the centre pole

The going you measure on that line is the one that has to pass. It must meet Table 11.2.2a:

What	Minimum	Maximum
Going (standard)	240 mm	355 mm
Going (spiral)	210 mm	370 mm
Riser (standard)	115 mm	190 mm
Riser (spiral)	140 mm	220 mm

If you’re using winders instead of a landing, every winder must have the same going — a constant step round the whole turn. You can’t have a couple of generous ones and then a tight one that catches a heel.

NCC 2025 Housing Provisions 11.2

1 walking line
2 winder tread
3 landing

Where winders are allowed. Only in place of a landing, at a turn — never part-way along a straight flight. Up to 3 winders make a quarter turn (90 degrees). Up to 6 winders make a half turn (180 degrees). Any more than that and you need a landing instead.

Landings. A flight can have at most 18 risers and at least 2. That cap is what forces a landing into a long run — you can’t just keep stacking steps forever. The landing rules (clause 11.2.5):

At least 750 mm long.
On a turn, that 750 mm is measured 500 mm in from the inside edge — the tight side of the corner — so the short side can’t cheat the length.
No steeper than 1:50.
Must run the full width of any doorway that opens onto it.
You need a landing where a doorway opens onto a stair with a drop of more than 3 risers or 570 mm — so nobody steps straight out of a door into a fall.

Work it out by hand

You’re framing a quarter turn at the bottom of a stair and you want to use 3 winders instead of a landing. The stair is 900 mm wide — under a metre — so the walking line runs down the middle.

Find the walking line. 900 mm wide, so the line sits at 450 mm — the centre of the tread.
Set the going on that line. Your treads have to give at least 240 mm of going measured on that middle line. Say you set them out so the walking line reads 250 mm — that clears the 240 mm minimum with a touch of room to spare, and sits well under the 355 mm maximum. (250 mm is just an example set-out, not a code figure — the code figure is the 240 mm minimum.)
Keep them equal. Because these winders replace a landing, all three must have the same going on the walking line. Mark and cut them off one story pole so they match.
Check the count. 3 winders for a 90-degree turn — that’s the limit, so you’re fine. Needed a full 180? You’d be allowed up to 6.

So: 3 equal winders, walking line down the middle, at least 240 mm of going on that line. That’s a legal quarter turn.

Do it in 5 seconds

Part of the NCC rules for Australian chippies — the pillar guide, with the state-by-state adoption tracker.
Getting the straight runs right first? See NCC stair requirements: riser, going & the 2R+G rule.
Fitting the barrier round the turn? See Balustrade height requirements: when do you need one?.

Sources

NCC 2025, ABCB Housing Provisions Standard, Part 11.2 (Stairway and ramp construction) — winder goings and the walking line (cl 11.2.2), Table 11.2.2a goings and risers, the 18/2 riser limits, and landings (cl 11.2.5). Confirm the 240 mm / 355 mm goings, the 115–190 mm risers, the 750 mm landing length, and the 3-winder quarter-turn / 6-winder half-turn rule at ncc.abcb.gov.au. (Confirmed against the NCC 2025 Housing Provisions Standard, verified 2026-07-28.)

Frequently asked questions

How do you measure the going on a winder?

You measure it along a walking line — the path someone's feet take round the turn. For a stair 1 m wide or less, that line runs down the middle. For a stair wider than 1 m, it sits 400 mm in from each side. On a spiral it's 0.7 of the width out from the centre pole. The going you measure on that line is what has to meet the code.

What is the minimum going on a stair winder?

Measured on the walking line, the going must be at least 240 mm (210 mm on a spiral) and no more than 355 mm (370 mm on a spiral). If you're using winders instead of a landing, every winder must have the same going — you can't mix wide and narrow ones.

How many winders can you use to turn a stair?

Up to 3 winders make a quarter turn (90 degrees). Up to 6 make a half turn (180 degrees). Winders are only allowed in place of a landing at a turn — never in a straight flight.

When do you need a landing on a stair?

A flight can have at most 18 risers and at least 2, so a long run has to be broken up with a landing. You also need a landing where a doorway opens onto a stair with a drop of more than 3 risers or 570 mm. A landing must be at least 750 mm long, no steeper than 1:50, and run the full width of any doorway.

How long does a stair landing have to be?

At least 750 mm. On a turn, you measure that 750 mm 500 mm in from the inside edge — the tight side of the corner — so the short side doesn't cheat the length. The landing also has to be no steeper than 1:50.