an &# 34 ; off the shelf &# 34 ; modular staircase system is described that allows for a flexible fit of the staircase into custom plan areas and / or areas in which the ceiling - to - floor height varies . the modules form a complete staircase and not a mere skeleton of a staircase . furthermore , the modular staircase system , because it allows for the mass production and conventional transportation of the various stair modules , results in the reduced cost of a staircase and reduced construction time . individual stair modules may be formed as a unitary structure out of a moldable material .