The angle of the stairs slope to the horizontal is 20° to 45°, but it is recommended to have the range between 30° and 38°.
Stairways shall be ≥ 600mm wide inside the stiles and it is to have a minimum clearance of 550mm between rails.
For stair landing; the width of the landing shall not be less than the stairway width and a minimum of 600 mm clear of cross-traffic, door swing or any other structure.
Minimum headroom is typically 2000 mm, this may need to be increased if helmets are worn. In applications where the minimum headroom cannot be achieved, other measures should be taken, Such as signage, padding and highlighting.
The maximum of 18 risers in a flight. Adjacent flights shall be connected using a landing.
Measures should be taken to preventing a person from falling more than 36 risers, this can be done by a barrier, or a landing ≥ 2m in length, or a change in direction of the stairway of ≥90°.
The tread shall extend across the full width of the stairway and the tread surface shall be slip-resistant. The nosing shall be such that the edge of the tread is clearly visible against the background.
|The Riser (R)||The going (G)||
The slope relationship (2R + G)
The tread depth (TD) is to be ≤185mm and it should not be more than 30mm shorter than the going (G).
All risers and all goings in the same flight of stairs shall be of uniform dimensions within a tolerance of ±5 mm.
Except where there is a fixed structure within 100 mm of the stairway stile, stairways and stairway landings shall be provided with guardrailing on any exposed side.
Every stairway shall have at least one handrail and a handrail on each side for stairway wider than 1000mm.(refer: to handrails and guardrails for details).
Stairs Landing shall have a minimum live loading of 2.5 kPa and minimum point loading of 1.1 kN applied on 100mm × 100mm pad.
Treads shall have a minimum live loading of 2.5 kPa, or a 2.2 kN per linear metre or minimum point loading of 1.5 kN applied on 100mm ×100 mm pad on each step, whichever loading produces the more adverse effect.
The maximum deflection shall be L/100 or 40mm, whichever is the lesser, over the horizontal span (L) of the stairway between supports
If the stairs are likely to be loaded in excess of the above requirements, refer to AS/NZS 1170.1.