Stair Regulations Australia: NCC Rules for Houses

Under the NCC Housing Provisions for houses (Class 1) and Class 10 buildings, a stair other than a spiral stair must have risers of 115 to 190 mm, goings of 240 to 355 mm and a slope relationship (2R + G) of 550 to 700 mm, with 2 to 18 risers in each flight (Part 11.2, Table 11.2.2a). Where it is possible to fall 1 m or more, a barrier is required: at least 865 mm high above the stair nosings and 1 m high on landings, decks and balconies, with no opening that lets a 125 mm sphere through (11.3.3, 11.3.4). These values are identical in NCC 2022 and NCC 2025.

Summary table

Rule	Metric	Imperial	Housing Provisions
Riser (R)	115–190 mm	4 9/16–7 7/16 in	11.2.2, Table 11.2.2a
Going (G)	240–355 mm	9 1/2–13 15/16 in	Table 11.2.2a
Slope relationship 2R + G	550–700 mm	21 11/16–27 1/2 in	Table 11.2.2a
Risers per flight	2 to 18	2 to 18	11.2.2(1)(a)
Difference between adjacent risers or goings, maximum	5 mm	3/16 in	11.2.2(1)(c)
Largest minus smallest in a flight, maximum	10 mm	3/8 in	11.2.2(1)(c)
Open risers	no 125 mm sphere	4 7/8 in	11.2.2(1)(d)
Spiral stair: riser / going	140–220 / 210–370 mm	5 9/16–8 5/8 / 8 5/16–14 9/16 in	Table 11.2.2a
Landing length, minimum	750 mm	29 9/16 in	11.2.5
Headroom	2.0 m	78 3/4 in	10.3.1(1)(f)
Barrier required where a fall is	1 m or more	39 5/16 in or more	11.3.3
Barrier height: stair / landing, deck, balcony	865 mm / 1 m	34 1/16 / 39 3/8 in	11.3.4(2)
Openings in barriers	no 125 mm sphere	4 7/8 in	11.3.4(4)
Handrail height, minimum	865 mm	34 1/16 in	11.3.5

Imperial values are rounded to 1/16 in on the safe side.

Which code applies: NCC 2022 or NCC 2025

The National Construction Code (NCC) is produced by the Australian Building Codes Board (ABCB) and given legal effect by state and territory legislation; each state and territory sets its adoption date. Houses (Class 1) and Class 10 buildings such as private garages, carports and sheds fall under NCC Volume Two, whose Deemed-to-Satisfy route for stairs is Part 11.2 of the ABCB Housing Provisions (H5D2), and for barriers and handrails Part 11.3 (H5D3).

NCC 2025 was published on 1 May 2026. According to the ABCB, Victoria adopted it on 1 May 2026, and the ACT and Western Australia on the same date with a 12-month transition. New South Wales and Queensland list 1 May 2027, South Australia 1 May 2027 for the building code, and Tasmania 1 May 2027 after a temporary adoption from 1 May to 4 June 2026. The Northern Territory has not adopted it. We compared both editions: the values in this guide are the same, and neither edition's state and territory schedules vary Parts 11.2 or 11.3.

Risers, goings and 2R + G (11.2.2)

The NCC defines the riser as the height between consecutive treads, and the going as the horizontal depth of a tread less any overhang from the tread or landing above. Both must sit inside Table 11.2.2a, and 2R + G must fall between 550 and 700 mm. That check narrows the table: with 190 mm risers the going can be at most 320 mm, and a 115 mm riser needs a going of at least 320 mm.

Risers and goings must be constant: adjacent ones may differ by no more than 5 mm, and the largest and smallest in a flight by no more than 10 mm. Each flight has 2 to 18 risers, winders included. Treads must be solid, not mesh or perforated, if the stair is more than 10 m high or connects more than 3 storeys.

Common mistake: forgetting floor finishes, which can push the top or bottom riser past the 5 mm limit.

Open risers (11.2.2(1)(d))

Open risers are allowed if no opening between treads lets a 125 mm sphere through. A 175 mm riser with a 40 mm thick tread leaves a gap of about 135 mm, so it needs a riser bar. Stairs serving only non-habitable rooms used infrequently, such as attics and storerooms, may use Table 11.2.2b (risers 130–225 mm, goings 215–355 mm, 2R + G 540–700 mm) and are exempt from the open-riser rule (11.2.2(2)).

Winders and tapered treads (11.2.2(3) and (4))

A flight may have up to 3 consecutive winders in place of a quarter landing, and up to 6 in place of a half landing. Winders may have a different going from the straight treads, provided all the winders share the same going. For the 2R + G check on tapered treads, measure the going in the middle of a stair up to 1 m wide, or 400 mm in from each side of a wider stair; on a spiral stair, measure at seven tenths of the width out from the centre pole.

Nosings and slip resistance (11.2.4)

Unlike the US IRC, Part 11.2 sets no nosing projection range. It does require slip resistance tested to AS 4586: tread surfaces P3 or R10 in dry conditions and P4 or R11 in wet conditions, or a nosing strip rated P3 dry or P4 wet (Table 11.2.4). A landing whose edge leads to a flight below needs the same rating for 190 mm back from the nosing, or a nosing strip. Areas exposed to the weather count as wet.

Landings and thresholds (11.2.5, 11.2.6)

Landings must be at least 750 mm long, measured 500 mm in from the inside edge where the stair changes direction, with a gradient no steeper than 1:50. A landing is also needed where a doorway opens onto a stair or ramp that drops more than 3 risers or 570 mm, and it must extend across the full width of the doorway. A threshold more than 230 mm above the adjoining surface needs steps that comply with 11.2.2.

Headroom (10.3.1)

Part 10.3 requires a height of 2.0 m above a stairway or landing, measured vertically above the nosing line of the treads or the floor of the landing (10.3.1(1)(f)).

Barriers (11.3.3, 11.3.4)

A continuous barrier is required along a stair, ramp, floor, deck, balcony or the like where it is possible to fall 1 m or more to the surface beneath. It must be at least 865 mm above the stair nosings and at least 1 m above landings, decks and balconies; 865 mm is accepted along the inside edge of a landing for up to 500 mm, and a transition zone is allowed where the height changes. No opening may let a 125 mm sphere through, measured above the nosing line on a stair, and the gap between a barrier and the edge it is fixed to may not exceed 40 mm. Where the fall is more than 4 m, horizontal elements between 150 and 760 mm above the floor must not make the barrier climbable. Wire balustrades built to 11.3.6 meet the opening rule.

Common mistake: running the 865 mm stair height along the whole landing, where 1 m applies.

Handrails (11.3.5)

A handrail is required along at least one side of each flight, for its full length, with its top at least 865 mm above the nosings. It must be continuous, interrupted only by newel posts, ball-type stanchions or the like, and when it is part of a barrier it may stop where the barrier stops. No handrail is required on a stair that changes elevation by less than 1 m, on a landing, or at winders where a newel post gives a handhold. Part 11.3 sets no maximum handrail height.

Design my stair

FAQ

What is the maximum stair riser height in Australia?

190 mm for a stair other than a spiral stair, with a minimum of 115 mm (Table 11.2.2a). Spiral stairs allow up to 220 mm.

What is the minimum going for stairs in Australia?

240 mm, up to 355 mm (Table 11.2.2a). With 190 mm risers, the 2R + G limit of 700 mm caps the going at 320 mm.

How many steps can a flight of stairs have?

Between 2 and 18 risers per flight, winders included (11.2.2(1)(a)). A taller stair must be split into flights by landings.

When is a balustrade required on stairs or a deck?

Where it is possible to fall 1 m or more. The barrier must be at least 865 mm high on the stair and 1 m on landings and decks, with no gap that lets a 125 mm sphere through (11.3.3, 11.3.4).

Are the stair rules different in NSW, Victoria or Queensland?

Not for stair geometry: NCC 2022 and NCC 2025 use the same values, and the state and territory schedules do not vary Parts 11.2 or 11.3. Which edition applies depends on your state's adoption date, so confirm with your building surveyor or certifier.

Stair3D gives you a design and a code check to guide your work. Check the measurements on site and with your local building authority before cutting.