# Steps on stairs in groups of 8

I have noticed than most buildings with stairs, seem to group into 8 steps or 16 before each break, unless the total of steps are for example 6 or 10 and more/less steps would mean too high or too low steps.

Is this a world-wide thing, and why 8?

• 12 is quite common as well Commented Mar 7, 2012 at 14:14
• Because obviously binary exponents are superior numbers Commented Mar 7, 2012 at 14:15

At least in the US, there are codes that dictate what range the riser-height of stairs must fall within for new buildings. That fact, coupled with fairly standard heights between floors of buildings, is what determines how many stairs are needed to go between floors.

Also, due to space constraints, staircases are often wound back on themselves to have a smaller footprint, meaning that you will get a landing roughly 1/2 way between floors. So, if it takes 16 steps to get from one floor to another, each flight of stairs will be 8 steps and will wind around itself.

I'm sure that there have been studies done on optimal riser height and the number of risers in a flight for various activities and body measurements, but in my experience, it is less of a "what's best for people" decision and more of a "what meets code and what fits in the available space" decision.

• It sounds like you're talking from experience. Can you provide a link to the US building regulation codes you refer to?
– JonW
Commented Mar 7, 2012 at 14:31
• @JonW, A number of my family members are in the construction and architecture business (I am not, myself), so I don't have any direct experience with this, but I do know that most of the building codes are "local", often being set at the State level in the US, but occasionally at the county or city level. I've added a couple of links to some resources on this, but other than that I don't have too much more for concrete resources. Commented Mar 7, 2012 at 14:41

There might be many reasons, but the ones I know:

1) People who cant see, usually count the number of stairs while climbing them. So having them consistent everywhere will help them.

2) The height of steps need to be at an optimum level, people trip more in average if the height is increased beyond that level.

• The depth of the steps is important too. Commented Mar 7, 2012 at 14:42