April 19, 2015
You are absolutely correct.
A spiral staircase cannot be used as a means of egress in a commercial building, except within a dwelling unit.
January 22, 2016
Have a commercial building with A-2 on first floor and R-2 on the second floor. They are wanting to remove an old staircase and replace with a spiral staircase. This would be the sole means of egress from the second floor with the exception of window. There are four apartments on the second floor and the entire second floor is greater than 250 sq. ft. I am confused as to the wording " Spiral stairways are permitted to be used as a component in the means of egress only within dwelling units or from a space not more than 250 sq. ft. in area............" Does this mean that spiral staircases are only allowed in the interior dwelling unit and not on the exterior as a means of egress? I am thinking that they would not be allowed to have a spiral staircase as their only means of egress that the "within dwelling units" refers to a spiral staircase leading from a second floor to a first floor within a dwelling unit. Am i missing something?