Circular Staircase Classifications & Standards

A circular staircase utilizes a large radius coupled with a somewhat smaller radius. These two curves commonly share the same center point. The distance between the two curves (radii) creates the width of the staircase. A spiral staircase utilizes a center support post with the stair treads arranged much as the spokes of a wagon wheel would be around the hub. While a circular stair can also be called a "curved" stair, the spiral stair is a vastly different design usually reserved for very limited spaces. Spiral stairs can only be used as secondary stairs in limited applications. A circular stair will meet code when designed and built properly. An elliptical staircase is built from a totally different geometry than a circular or spiral. While the circular and spiral designs have a center point and consistent curvature, the elliptical design has a complicated, ever-changing curvature that uses multiple axis and focus points. While an elliptical design technically is a curved stair, a distinction between circular and elliptical must be made.