The Five-Second Check of Stair Rise and Run

Because falls on stairs can cause especially severe injuries and even deaths, building codes for stairs are very stringent. When we use stairs that are properly constructed, we can walk with ease and converse at the same time, nearly unaware that our feet are performing a rather complex operation.

Ease and safety depend on each step in the stairs being the same in height (rise) and length (run). In general rises must be 4–7 inches and tread depths 11 inches minimum, but check the applicable building code. Modern codes generally require that the tolerance between the largest and smallest riser or between the largest and smallest tread shall not exceed 3/8” in any flight of stairs.

That uniformity can be a bit tedious to measure directly, but here’s a simple way of making a 5-second check. This technique would hardly qualify as primary evidence in court, but it can be a useful means of finding dimensional faults in straight flights of stairs. Because the building codes’ dimensional tolerances are so tight, a step that’s out of specification can in some cases stick out like a sore thumb.

Stand at the top of the stairs, a few feet back from thefirst step so that your eyes are nearly lined up with the nosings of the steps.Your eyes need to be slightly above the line of nosings so that you can see each nosing; see the photo below.


Stair dimensions that don’t show prominent nonuniformity

If you can’t see each nosing from that position, forinstance if you can see all except  for one, that’s an indication that something is wrong. If you can see each nosing, but one of them appears to be different in relative location from the rest, that’s also an indicator. Now please look at the next photo and without reading the caption, see if you can detect where the problem is.  In many cases the five-second check of every stairway in a building is a great way to find major stair dimensional faults before an accident happens.


A schoolteacher was injured when she stepped down to the second and third treads, assuming that their rise and run were the same as those of the first step down — but they weren’t

Slip-resistant marking stripes (tape or paint) 1–2 inches in width up to one inch back from the nose can help pedestrians in walking safely on the stairs. If a rise or run is nonuniform, the stripe should be different from any other nosing marking on the flight. We offer anti-slip tapes and clear, abrasive anti-slip floor coatings on our Anti-Slip Floor Superstore website.