Per osha 1910 23 b 4 ladder rungs steps and cleats have a minimum clear width of 16 inches measured before installation of ladder safety systems for fixed ladders.
Fixed ladder rung width.
For fixed ladders consisting of wood side rails and wood rungs or cleats used at a pitch in the range 75 degrees to 90 degrees and intended for use by no more than one person per section single ladders as described in 1910 25 c 3 ii are acceptable.
The minimum clear width of rungs on fixed ladders shall be 16.
There are exceptions for ladders in elevator shafts or on telecommunications towers.
The international mechanical code 2018 306 5 4 calls for a minimum of 18 between rails.
1917 118 e 2 when a well or cage is used ladders with length of climb exceeding 30 feet 9 14 m shall comply with the following provisions.
All fixed ladders have rungs dictated by osha standard 1910 27 b 1 of no more than 12 300 mm on center measured as the distance from the centerline of a rung to the center line of the next rung and at 16 410 mm clear width.
Individual metal rungs embedded in concrete pits minimum 1 inch diameter.
The distance between rungs cleats and steps does not exceed 12 inches and is uniform throughout the length of the ladder.
Fixed ladders more than 20 feet 6 1 m in height shall be provided with a cage well or ladder safety device.
Rungs and cleats ladder minimum diameter 3 4 inch metal rungs.
10 minimum and 14 maximum spacing from centerline to centerline of rungs.