Abstract: A spiral stair case wherein segments of the outside stringer framework and segments of the central column are forming corresponding polygonal segments, wherein the spiral stair case preferably is made in octagonal polygonal segments, wherein one segment of the outside stringer together with one segment of the central column respectively is supporting preferably two stair treads of the the spiral stair case, wherein the segments of the outside stringer and the segments of the central column are strait, non curved elements, and wherein the stair treads are made strait and wherein all peripheral cuts are made strait, and wherein the segments are connected to each other by standard carpentry connection means, wherein the fascia, the baluster posts, the baluster filler parts and the handrail build the rigid outside stringer segments, wherein the outside stringer segments build a rigid, structural supporting outside stringer framework of the spiral stair case formed in polygonal segments and wherein the segments ar