Stairway Design Requirements Including Rise and Going

What This Requirement Covers

This requirement sets the mandatory dimensional and geometric controls for stairways in buildings regulated under the National Construction Code (NCC) and associated Housing Provisions in Australia. It defines acceptable riser and going sizes, the relationship between them, limits on the number of risers per flight, and measurement rules so stairs are safe, predictable and usable by the intended occupants. The rules exist to reduce trip and fall risk by keeping step heights and depths consistent and within human factors limits, and to ensure egress routes perform reliably in everyday use and in an evacuation.

The requirements apply to designers, builders, certifiers and owners of buildings across classes regulated by the NCC (Class 1 to Class 9 and associated parts). Specific provisions apply differently to required exits, public stairways, private stairways inside sole-occupancy units, and less-frequently used or non-required stairs. Where relevant, the ABCB Housing Provisions and referenced Australian Standards provide additional measurement guidance and construction practice.

Key Requirements

1. Riser (R) and Going (G) relationship - the relationship 2R + G must fall within the prescribed minimum and maximum values for the stair type and location as specified in the NCC and Housing Provisions.
2. General public and private stair limits (NCC Volume One, Table D3D14 and Table G4D5):
3. For public stairways: Riser maximum 190 mm, minimum 115 mm; Going maximum 355 mm, minimum 250 mm; 2R + G must be between 550 mm and 700 mm (see Table D3D14).
4. For private stairways (private defined as stairways in a sole-occupancy unit in a Class 2 building or Class 4 part, or non-required stairways not normally accessed by the public): Riser maximum 190 mm, minimum 115 mm; Going maximum 355 mm, minimum 240 mm; 2R + G between 550 mm and 700 mm (see Table D3D14 and Note 1 to Table D3D14).
5. Alternate stair dimensions (NCC Volume One, Table G4D5): Riser maximum 150 mm, minimum 115 mm; Going maximum 375 mm, minimum 355 mm; 2R + G between 605 mm and 675 mm (see Table G4D5).
6. Housing Provisions (ABCB Housing Provisions Standard 2022, Clause 11.2.2 and Table 11.2.2a/b):
7. Typical housing stairways (other than spiral): Riser maximum 190 mm, minimum 115 mm; Going maximum 355 mm, minimum 240 mm; 2R + G must be between 550 mm and 700 mm (see Table 11.2.2a).
8. Spiral stairs (housing provisions): Riser maximum 220 mm, minimum 140 mm; Going maximum 370 mm, minimum 210 mm; 2R + G between 590 mm and 680 mm (see Table 11.2.2a).
9. For stairways serving non-habitable rooms used infrequently, alternate maxima/minima apply (see Table 11.2.2b in the Housing Provisions).
10. Number of risers per flight (ABCB Housing Provisions 11.2.2(1)(a)): Not more than 18 risers and not less than 2 risers per flight for a stair to be treated as a stairway in housing provisions.
11. Consistency tolerances (NCC and Housing Provisions):
12. Variation between adjacent risers or adjacent goings must not exceed 5 mm.
13. Variation between the largest and smallest riser or going within a flight must not exceed 10 mm (see ABCB Housing Provisions explanatory notes and NCC measurement rules).
14. Measurement location for tapered or spiral treads (NCC Volume One, Table D3D14 and associated notes; Housing Provisions Figure 11.2.2f):
15. For tapered treads the going is measured at specified offsets from the tread edges (examples: 270 mm in from outer side for narrow non-required stairways; 270 mm from each side for stairways 1 m or wider as specified in notes to Table D3D14 and Figure 11.2.2f).
16. Flight configuration rules (NCC Volume One, D3 requirements and Housing Provisions):
17. For required stairways in exits, winders are not permitted in lieu of a landing (see NCC Volume One D3 provisions for required stairways).
18. Non-required stairways may include limited winders - maximum 3 winders in lieu of a quarter landing and maximum 6 winders in lieu of a half landing (see NCC Volume One D3).
19. Tread construction and slip resistance (NCC Volume One D3D):
20. Treads must meet slip-resistance classifications listed in Table D3D15 when tested in accordance with AS 4586; stair treads for stairways more than 10 m high or connecting more than 3 storeys must be of solid construction (not mesh) (see NCC Volume One D3D requirements).
21. References to Australian Standards where applicable: the NCC and Housing Provisions reference measurement/installation standards and accessibility standards such as AS 1428.1 (accessible ramps where ramp elements are involved) and slip resistance testing AS 4586. Construction practice for structural timber/stairs should follow AS 1684 where relevant and other material standards as applicable.
22. Exact clause citations used in these points include: NCC Volume One - Table D3D14; Table G4D5 (alternate dimensions); NCC Volume One - D3 (Access and egress) provisions; ABCB Housing Provisions Standard 2022 - Clause 11.2.2 and Tables 11.2.2a and 11.2.2b.

Residential vs Commercial

1. Residential (Class 1 and associated Class 10/sole-occupancy Class 2 interior stairways):
2. Housing Provisions apply directly where relevant: typical limits R 115-190 mm, G 240-355 mm, 2R + G between 550-700 mm for normal housing stairs (see ABCB Housing Provisions, Clause 11.2.2 and Table 11.2.2a).
3. Spiral stairs in dwellings have separate, slightly different limits (see Table 11.2.2a).
4. Private stairways inside a sole-occupancy unit that are not required exits can use the private stair limits in Table D3D14 and Housing Provisions notes.
5. Commercial and other building classes (Class 2 to Class 9):
6. Required stairways used as exits and stairways in public areas must meet the NCC Volume One D3 requirements and Table D3D14. Typical public stair limits are R 115-190 mm, G 250-355 mm, 2R + G between 550-700 mm.
7. Higher duty requirements apply for means of egress: no winders in lieu of landings for required stairways, limits on consecutive risers in some building types (for example Class 9b - not more than 36 risers in consecutive flights without a change in direction of at least 30 degrees) and stronger expectations for slip resistance and tread construction (see NCC Volume One D3D and Table D3D15, and specific building class clauses).

Exceptions and Exemptions

1. Alternate dimensions: The NCC provides an alternate set of riser/going dimensions (Table G4D5) with more restrictive 2R + G limits that may be used where applicable. These alternates give designers flexibility where lower riser heights and larger goings are preferred (see Table G4D5 in NCC Volume One).
2. Non-required stairways: Some design relaxations apply to non-required or private stairways (for example slightly smaller minimum goings, tapered tread measurement methods, and limited use of winders in non-required stairs) as noted in NCC Volume One and Housing Provisions.
3. Site-specific variation at discharge: Where a stair discharges to a sloping public walkway or road, the riser may be reduced to account for the slope and the 2R + G relationship may vary at that location (see NCC Volume One D3 notes).
4. State schedules: states and territories may modify national provisions through their schedules to the NCC; those local provisions can provide exemptions, additional requirements or refinements - always check the relevant state schedule (see State and Territory Variations below).

State and Territory Variations

1. The NCC is national, but each state or territory may include a schedule that amends or supplements NCC provisions. Designers and certifiers must check the relevant state or territory schedule in NCC 2022 Volume One (Schedules 4-12) for any local changes.
2. Examples to consider (verify current text in the applicable state schedule when designing):
3. Queensland provisions appear in Schedule 7 and may include variations relevant to exits and egress in some building classes - check Schedule 7 of NCC 2022 Volume One.
4. Other jurisdictions may include differing fire safety, access or verandah treatment provisions that alter how stair discharge, handrails or treads are treated; check the state schedule in NCC 2022 Volume One for Schedules 4-12 as applicable to NSW, VIC, QLD, WA, SA, TAS, ACT and NT.
5. Always confirm with the relevant state schedule because local amendments can change dimensional tolerances, required materials, or additional requirements for accessibility or fire safety.

Practical Compliance Tips

1. Use the 2R + G check as an early design rule: select your riser height and confirm the going so that 2R + G lies within the permitted range for the stair type you are designing (public, private, spiral, or alternate table).
2. Keep risers and goings uniform: ensure the difference between adjacent risers or goings is no more than 5 mm, and the maximum difference within a flight is no more than 10 mm to avoid trip hazards and noncompliance.
3. Measure tapered and spiral treads correctly: apply the measurement offsets specified in the NCC (for example 270 mm offsets) and the Housing Provisions figure measurements to confirm your going complies at the correct distance across the tread.
4. For required exits avoid winders: do not use winders in place of landings in required stairways - use landings at appropriate intervals and direction changes (see NCC Volume One D3D).
5. Check slip resistance and tread construction early: specify slip-resistant nosing or tread finishes tested to AS 4586, and specify solid treads where the stair exceeds 10 m in height or connects more than 3 storeys (NCC Volume One D3D requirements).
6. Count risers correctly at design stage: ensure no more than 18 risers per flight in housing stairs (Housing Provisions) and check other building-class-specific limits (for example Class 9b restrictions on consecutive risers without direction change) in NCC Volume One.
7. Always cross-check state schedules and cite clauses: when preparing documents for a certifier or council, reference the exact NCC clause and table you used - for example, “NCC 2022 Volume One, Table D3D14” or “ABCB Housing Provisions 2022, Clause 11.2.2 and Table 11.2.2a” - and check the relevant state schedule in NCC 2022 Volume One for any local amendments.

Cited sources: NCC 2022 Volume One - Table D3D14; Table G4D5; D3 (Access and egress) provisions. ABCB Housing Provisions Standard 2022 - Clause 11.2.2 and Tables 11.2.2a and 11.2.2b. AS 4586 (slip resistance testing) and AS 1428.1 where accessibility interfaces apply.

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