Navigating the intricacies of stair design and construction in Australia requires adherence to specific standards and regulations to ensure safety and compliance. This guide provides an overview of the key requirements as stipulated by Australian standards and the National Construction Code (NCC).
1. Stair Dimensions and Design
Risers and Goings:
Riser Height: Must be between 130 mm and 225 mm.
Going Depth: Should range from 215 mm to 355 mm.
Uniformity: All risers and goings within a flight must be uniform, with a tolerance of ±5 mm.
Slope Relationship:
The formula 2R + G (where R is riser height and G is going depth) should result in a value between 540 mm and 700 mm to ensure comfortable stair usage.
Stairway Angle:
Stairways should have an angle between 20° and 45°, with a recommended range of 30° to 38° for optimal safety and comfort.
2. Treads and Nosing
Tread Requirements:
Treads must extend the full width of the stairway and have a minimum depth of 185 mm.
Surfaces should be slip-resistant to prevent accidents.
Nosing Specifications:
Nosings should be slip-resistant and clearly visible against the background to enhance safety.
3. Handrails and Balustrades
Handrails:
Required on at least one side of stairways; if the stairway is wider than 1000 mm, handrails must be on both sides.
Height should be between 865 mm and 1000 mm, measured from the pitch line.
Handrails must be continuous and easy to grasp, with a clearance of at least 50 mm from adjacent structures.
Balustrades:
Required when there is a risk of falling more than 1 meter.
Must be at least 1000 mm high on landings and 865 mm on staircases.
Openings should not allow a 125 mm sphere to pass through, ensuring child safety.
4. Landings and Flights
Flights:
A maximum of 18 risers is allowed in a single flight.
After 36 risers, a landing or change in direction (minimum 90°) is required to prevent fatigue and falls.
Landings:
Must be at least as wide as the stairway and have a minimum length of 750 mm.
Should be provided at the top and bottom of each flight and where doors open onto stairways.
5. Slip Resistance
Requirements:
Stair treads and nosings must meet slip resistance classifications as per AS 4586.
For dry conditions, treads should be at least P3 or R10; for wet conditions, P4 or R11.
Nosing or landing edge strips should be at least P3 in dry and P4 in wet conditions.
6. Accessibility Considerations
Compliance with AS 1428:
Handrails must extend horizontally at least 300 mm beyond the top and bottom of the stairs.
Tactile Ground Surface Indicators (TGSIs) are required at the top and bottom of stairways to assist visually impaired users.
7. Structural Integrity and Load Requirements
Load Capacities:
Stair treads must support a minimum live load of 2.5 kPa or a concentrated load of 1.5 kN applied on a 100 mm × 100 mm area.
Landings should also meet specific load requirements to ensure safety and durability.
8. Lighting and Visibility
Illumination:
Stairways must be adequately lit to ensure visibility at all times, reducing the risk of accidents.
Lighting should minimize glare and shadows to enhance safety.
Adhering to these stair requirements is crucial for ensuring safety and compliance in Australian buildings. For detailed information and guidance, refer to the National Construction Code and relevant Australian Standards such as AS 1657, AS 1428, and AS 4586.