Australian Design Rules for Stairs

The Building Code of Australia (BCA), now part of the National Construction Code (NCC), sets the design rules that govern staircase construction across Australia. Whether you're building a new home in Brisbane, renovating a Queenslander on the Sunshine Coast or adding a deck staircase in Moreton Bay, understanding these rules is essential.

Overview of the BCA

The NCC Volume 2 (formerly BCA Volume 2) covers residential buildings and sets out the requirements for staircase design in Part 3.9.1. These rules establish minimum standards for safety, accessibility and structural adequacy. All staircase construction in Queensland must comply with these requirements, and the QBCC enforces compliance through the building approval process.

Riser & Tread Dimensions

The most fundamental staircase design rules relate to riser height and tread depth (going):

• Riser height (R) — Minimum 115mm, maximum 190mm
• Tread going (G) — Minimum 240mm
• Riser/going formula — 2R + G must equal between 550mm and 700mm
• Consistency — Maximum 5mm variation between risers within a flight
• Nosing — Treads must have a nosing projection of 15mm to 25mm if risers are closed

These dimensions ensure a comfortable, natural stride when ascending or descending. Learn more about riser limits in our guide to the maximum risers per flight.

Staircase Width Requirements

The BCA sets minimum width requirements based on the building classification:

• Residential (Class 1) — Minimum 600mm clear width, though 860mm+ is standard
• Multi-residential (Class 2) — Minimum 1000mm clear width
• Commercial (Class 5–9) — Minimum 1000mm, increasing based on occupant load

Clear width is measured between handrails or between the wall surface and the handrail. Projections from the handrail into this space are limited to 25mm per side.

Handrail Rules

Handrails are a critical safety element and the BCA sets detailed requirements:

• Height — Between 865mm and 1000mm measured vertically from the nosing line
• Graspability — The handrail profile must be graspable, with a circular cross-section of 32mm to 65mm diameter, or equivalent
• Extensions — Handrails must extend horizontally at least 300mm beyond the top and bottom risers
• Continuity — Handrails must be continuous along the full length of the flight and across landings

Balustrade Requirements

Balustrade regulations protect against falls from the open side of staircases:

• Height — Minimum 865mm on the stair flight, 1000mm on landings and balconies
• Gap restrictions — No opening may allow a 125mm sphere to pass through (to prevent child entrapment)
• Climbability — Balustrades must not have horizontal elements that create a climbing hazard for children within 150mm to 760mm above the floor
• Structural loading — Must withstand a horizontal force of 0.60kN/m applied to the top

Landing Requirements

Landings provide rest points and turning areas within a staircase:

• Maximum risers per flight — 18 risers before a landing is required
• Landing depth — Minimum 750mm in the direction of travel
• Landing width — At least equal to the staircase width
• Doors near landings — Doors at the top of stairs must not encroach on the required landing area

Headroom Clearance

The BCA requires a minimum headroom clearance of 2,000mm measured vertically from the nosing line to any overhead obstruction. This ensures safe passage for tall occupants and when carrying items up and down the staircase.

As QBCC licensed staircase builders (Licence #69007), Craftsman Stairs ensures full compliance with all Queensland building regulations on every project across Brisbane, Moreton Bay and the Sunshine Coast. Contact us for expert advice on your staircase design.