5. Circular staircases

5.1 General

• Definition

  The third family is made up of circular staircases, i.e. staircases whose entire layout forms part of a cylinder, with the outside and inside forming two helixes, and whose tread line is circular. These staircases are often referred to as helical staircases or spiral staircases, when the treads are arranged on a central core. They are mainly found on :

  • as individual staircases for moving from one floor to the next with a minimum of space and hopper cross-section;

  • as fire escapes in multi-family buildings, with a step width corresponding to two passage units;

  • as architectural staircases, isolated...