Square stairwell with spiral staircase - has staggered treads supported between central pillar and stairwell wall, and inclined tread channels for grouting

摘要

The spiral staircase has a central post (5) with a hollow (7) at the base where it rests on a floor stub (6) with corresponding raised shoulder (16). The treads have a channel (9) running between the outside of the stairwell and the central post. Reinforcing steelwork protrudes from the floor stub (13) and helical steelwork (12) also ties the threads to the post. The treads are supported at the outside of the stairwell and concrete grout is poured down the channels and into the space between the post and floor stub. The staircase is designed for use in a square stairwell.