Australian Standard AS1657-2018

BASIC DIMENSIONS

• The maximum height a step ladder can extend between landings is 6 m.
• Step ladders incline angle nominally between 70° and 90° but it is preferred to design them between 70° and 75°
• The width of the step ladder between the stiles is 375mm to 525mm.
• The stile may be of any shape, provided it fits within a circle 40mm≤ dia ≤ 80mm.

CLEARANCES

• The minimum clearance required for a rung ladder is 200mm from the back edge of the rung to any structure behind it.
• Front clearance shall be a distance of 750mm from the nosing of the rung measured at perpendicular to the ladder.
• At the sides, clearance is 350mm from the centre-line of the ladder at 135° angle from the stiles.   
• Minimum headroom is typically 2000mm, this may need to be increased if helmets are worn.
• The hand clearance for stiles shall be not less than 50mm. 

DIMENSIONS/details of Rung

• The rungs diameter shall be 20mm ≤ dia ≤ 50mm.
• For ladders greater than 1m, a rung spacing 250 mm ≤ spacing ≤  300 mm. tolerance of ±5 mm or better.
• The distance between the bottom rung/tread and the bottom landing shall be 90% to 100% of the rung spacing
• The top rung shall be level with, or be integrated into, the landing.
• Rungs shall be securely connected to the stiles and shall not rotate.
• The surface of rungs shall be slip resistant.

Landing

• The width of the landing shall be not less than 600mm.
• Landing length shall provide standing space ≤600mm clear of cross-traffic, door swing or any other structure.
• Top landing length shall be ≤900 from the front of the ladder.
• The maximum permissible cross-slope at bottom landing is 7°

PROTECTION FROM FALL

• The maximum height a step ladder can extend between landing with out added protection is 6m ≥70° to 75° and 4.5m for ≥75° to 90° otherwise a multiple step ladders with an intermediate landings are required.  To limit the distance a person could fall, a change of direction by 180°, or staggering at each landing is required. All ladders are to be same in multiple-flight ladders.
• Where a person could fall more than 6 m to a level below, the step ladder must be fitted with a side screen, or a ladder cage to prevent fall.
• Where the above measures cannot be practicable other means can be implemented such as utilising a fall-arrest system complying with AS/NZS 1891.

Loading

• Refer to the standard.