People are dominantly right handed, so right hand on the wall. You need more space under your foot while descending, you only use the ball of your foot while g

People are dominantly right handed, so right hand on the wall. You need more space under your foot while descending, you only use the ball of your foot while going up. The stairs are thicker on the outside, so if that is on the right as you descend, the staircase will be counter clockwise.