Abstract: A wooden spiral staircase having a hollow central support column, treads which abut but do not attach to such column, tread supports ending in tenons which completely intersect the column and are secured by a wedged-through mortise joint, spacerblocks between every two adjacent treads and under the bottommost tread, and an optional laminate bent handrail and optional balusters which serve no support function, enabling the manufacturer to construct and ship the main body of the staircase as a single unit that can easily be installed through "screwing" it through the doorway(s) of the intended site. The method of constructing such a staircase in which the placement of the mortises on the central column is determined by the use of a computer generated template, thereby allowing for every staircase to be custom-designed as well as ensuring extreme precision in the final product.

Abstract: A wooden spiral staircase having a hollow central support column, treads which abut but do not attach to such column, tread supports ending in tenons which completely intersect the column and are secured by a wedged-through mortise joint, spacerblocks between every two adjacent treads and under the bottommost tread, and an optional laminate bent handrail and optional balusters which serve no support function, enabling the manufacturer to construct and ship the main body of the staircase as a single unit that can easily be installed through "screwing" it through the doorway(s) of the intended site. The method of constructing such a staircase in which the placement of the mortises on the central column is determined by the use of a computer generated template, thereby allowing for every staircase to be custom-designed as well as ensuring extreme precision in the final product.