Maximum Risers in One Flight of Stairs in Australia

Understanding the maximum number of risers allowed in a single flight of stairs is essential when designing a staircase for your Australian home. The Building Code of Australia sets clear limits to ensure safety and comfort. Here's what every homeowner in Brisbane, Moreton Bay and the Sunshine Coast needs to know.

BCA Riser Limits

The National Construction Code (NCC Volume 2, Part 3.9.1) stipulates that a single flight of stairs in a residential building may contain a maximum of 18 risers. After 18 risers, a landing must be provided before the staircase continues. This applies to all internal and external staircases in Class 1 and Class 10 buildings.

For commercial buildings (Class 2–9), the limit is typically 12 risers per flight under NCC Volume 1, with stricter requirements for handrails, width and fire egress.

Why Limits Exist

The riser limit is a safety measure designed to:

• Reduce fall distance — Shorter flights mean shorter potential falls, reducing the risk of serious injury
• Provide rest points — Landings allow users to pause during a long ascent, which is important for elderly residents and people with mobility limitations
• Prevent fatigue-related accidents — Extended climbs increase fatigue, which can lead to missteps
• Enable emergency egress — Landings provide orientation points and turning areas during evacuations

Riser Height Dimensions

The BCA also regulates individual riser heights for residential staircases:

• Minimum riser height — 115mm
• Maximum riser height — 190mm
• Preferred riser height — 165mm to 180mm is considered most comfortable
• Consistency — All risers within a flight must be within 5mm of each other in height

The relationship between riser height and tread depth (going) must also satisfy the formula: 2R + G = 550mm to 700mm, where R is the riser height and G is the going.

Calculating the Number of Risers

To determine how many risers your staircase needs, divide the total floor-to-floor height by your chosen riser height:

• Example: Floor-to-floor height of 2,700mm ÷ 175mm riser = 15.4 risers
• Round to 15 or 16 risers, then adjust the riser height to achieve an exact fit
• 16 risers × 168.75mm = 2,700mm (each riser is 168.75mm)

Since 16 is under the 18-riser maximum, this staircase can be built as a single flight. Higher ceilings common in Queenslander homes may require careful calculation to stay within limits.

What If You Need More Risers?

If your floor-to-floor height requires more than 18 risers, you have several options:

• Add a landing — Split the staircase into two flights with a flat landing, creating an L-shaped or U-shaped design
• Increase riser height — Using taller risers (up to 190mm maximum) reduces the total number of risers needed
• Consider a curved design — Curved staircases can accommodate height changes gracefully within the riser limits

QLD Requirements

Queensland adopts the NCC under the Queensland Development Code. The QBCC enforces these standards, and all staircase building work requires a licensed builder. Queensland stair regulations mirror the national code, with the 18-riser limit applying to all residential staircase construction.

As QBCC licensed staircase builders (Licence #69007), Craftsman Stairs ensures every staircase we design and build across Brisbane, Moreton Bay and the Sunshine Coast fully complies with riser limits and all BCA requirements. Contact us for a free quote.

Frequently Asked Questions