Temporary Stairway Check (OSHA 1926.1052)
The construction stairway, governed differently from a finished one in three ways. The stairrail trigger is a double condition read the unusual way -- four or more risers OR rising more than 30 in, WHICHEVER IS LESS, meaning whichever comes FIRST -- so a three-riser flight climbing 32 in is caught by the rise even though it fails the riser count. The angle is bounded on BOTH sides, 30 to 50 degrees: too shallow is a violation, not a courtesy, because a run under 30 degrees is a ramp with steps in it and people trip on it precisely because it does not read as stairs. And uniformity is a VARIATION ACROSS THE FLIGHT, not a tolerance per step -- not over 1/4 in in any stairway system, so individually reasonable steps still fail if the first and last differ.
Formula and source
angle = atan(riser height / tread depth) in degrees, required between 30 and 50; a stairrail is required where risers >= 4 OR total rise > 30 in (whichever comes first); uniformity passes where the worst of the riser-height and tread-depth variations is <= 1/4 in; stairrail height >= 36 in from its upper surface to the tread surface; landing depth >= 30 in in the direction of travel.
OSHA 29 CFR 1926.1052, Subpart X - Stairways and Ladders. A US federal regulation in the public domain, quoted directly.
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