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.
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.
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.
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