Australian Staircase Calculator (NCC)

Australian stairs are governed by the National Construction Code (NCC), which incorporates the Building Code of Australia (BCA). The NCC uses metric limits and, like the UK, restricts a flight by riser count rather than by total rise.

Australia NCC / BCA stair limits

Worked example — 9-foot floor-to-floor

For a 108-inch total rise under Australia NCC / BCA: dividing by the 7.48-inch maximum riser gives a minimum of 15 risers. Spreading 108 inches evenly across 15 risers yields 7.2 inches per riser — within the limit and uniform, as the code requires.

Run your stair against Australia NCC / BCA

What's distinctive about the NCC

The NCC caps the riser at 190 mm (about 7.48 in) and requires a going of at least 240 mm (about 9.45 in) for typical stairs — slightly gentler risers and deeper treads than the US IRC. Two features stand out compared with US codes:

• Flight limited by riser count: a flight is limited to 18 risers before a landing is required, rather than the US approach of capping vertical rise (147 in).
• The 2R + G rule: the NCC applies a going/riser relationship to keep stairs comfortable, similar in spirit to the Blondel rule.

The NCC also sets a tolerance on riser and going uniformity within a flight, and specifies slip-resistance and the familiar opening rule that restricts gaps in open-riser stairs. A stair designed to US residential numbers (7.75 in riser) will exceed the NCC's 190 mm riser limit and need redesign.

Other codes

Compare with IRC 2018, IRC 2021, IRC 2024, IBC, UK Approved Document K, Eurocode / EN.