Which building code applies in Australia, and what numbers does it set?
Published · Updated · By Sai Nath
Australian houses follow the National Construction Code: the NCC 2025 Housing Provisions, or NCC 2022 where a state hasn't switched yet. Stairs need risers of 115 to 190 mm and goings of 240 to 355 mm, a barrier goes wherever you could fall 1 m or more, with no gap a 125 mm sphere passes, and eaves gutters fall at least 1:500.
How does the NCC work for a house?
The Australian Building Codes Board writes the National Construction Code and publishes it free at ncc.abcb.gov.au. For a house, and its garage or shed (Class 1 and 10 buildings), the part you work from is the Housing Provisions, under Volume Two. The NCC has no force on its own: each state and territory calls up an edition from a date it chooses. NCC 2025 was published on 1 May 2026. On 1 November 2026 Victoria applies it, WA and the ACT accept it with NCC 2022 still allowed until 30 April 2027, and NSW, Queensland, Tasmania and South Australia switch on 1 May 2027. The dates and sources are in which NCC applies in each state.
The NCC calls up Australian Standards for the detail, AS 1684 for timber framing among them. Those are sold by Standards Australia, so this site quotes none of their text and links free sources that state what they require. The approved plans, your builder and your building surveyor or certifier decide what a job needs.
The numbers chippies use most
For stairs and balustrades the figures read the same in NCC 2022 and NCC 2025, so a stair worked out in one state passes the same check in another.
| What | Figure | Where in the Housing Provisions | Guide |
|---|---|---|---|
| Stair riser | 115 to 190 mm | Table 11.2.2a | Stair rules |
| Stair going | 240 to 355 mm | Table 11.2.2a | Stair rules |
| 2R + G | 550 to 700 mm | Table 11.2.2a | The 2R + G formula |
| Risers in one flight | 2 to 18 | 11.2.2(1)(a) | Stair rules |
| Headroom over a stair | 2.0 m above the nosing line | 10.3.1(1)(f) | Stairwell opening |
| When a barrier is needed | A possible fall of 1 m or more | 11.3.3(1) | Baluster gaps |
| Barrier height | 865 mm above stair nosings; 1 m on decks, balconies and landings | 11.3.4(2) | Baluster gaps |
| Openings in a barrier | Must not let a 125 mm sphere through | 11.3.4(4) | Baluster gaps |
| Ramp gradient | Not steeper than 1:8 | 11.2.3(2) | Ramp gradient |
| Eaves gutter fall | At least 1:500 | 7.4.4(1)(a) | Gutter fall |
Framing sizes and spacings don't come from the NCC's own pages: it points to AS 1684 and the span tables, and the sheet or board on top sets its own maximum. See stud spacing, joist spacing and noggin spacing.
Worked example: a stair and its balustrade
A house with 2700 mm from finished floor to finished floor, and a 240 mm going.
- Risers: 2700 ÷ 190 = 14.2, so at least 15 risers. 15 risers of 2700 ÷ 15 = 180 mm, inside 115 to 190.
- 2R + G: 2 × 180 + 240 = 600 mm, inside 550 to 700.
- Treads and run: 14 treads of 240 mm, 14 × 240 = 3360 mm of going.
- Barrier: the stair climbs 2.7 m, so the open side needs a balustrade 865 mm above the nosings, and the landing at the top 1 m, with no gap that lets a 125 mm sphere through.
Which MeisterCalc calculators help?
The app was made metric first for Australia. Stairs is free and warns when a riser goes over 190 mm or under 115 mm, the Table 11.2.2a limits. Baluster Spacing starts its Max Spacing at 125 mm and keeps every gap under it. Pitch turns a 1:500 fall into millimetres over a gutter run, and Stud Counter, Running Measurements and Concrete cover the frame and the slab. Stairs, Concrete and Check Square are free; the rest come with Pro. If you are studying, Cert III Carpentry maths, unit by unit maps the sums to the course.
Sources
Checked on 1 November 2026. These pages explain the rules; the code itself, your plans and your council, building consent authority, building control body or certifier decide what a job needs.
- NCC 2025 Housing Provisions, Part 11.2 Stairway and ramp construction: Table 11.2.2a, 11.2.2(1)(a), 11.2.3(2) (checked 1 November 2026)
- NCC 2025 Housing Provisions, Part 11.3 Barriers and handrails: 11.3.3(1), 11.3.4(2) and (4) (checked 1 November 2026)
- NCC 2025 Housing Provisions, Part 10.3 Room heights: 10.3.1(1)(f), headroom over a stairway (checked 1 November 2026)
- NCC 2025 Housing Provisions, Part 7.4 Gutters and downpipes: 7.4.4(1)(a), eaves gutter fall (checked 1 November 2026)
- ABCB, NCC 2025 state and territory adoption information: which edition each state applies, and from when (checked 1 November 2026)
Do the maths in MeisterCalc
MeisterCalc does the arithmetic behind these rules on an Android phone, with no signal needed: Stairs, Concrete and Check Square are free, and the other calculators come with Pro. It runs on Android 7.0 or later.