What size diameter do you need for a spiral staircase?
The answer to this extremely common question is that it depends on the usage of the staircase. The requirements for spiral staircases in the UK are described in British Standard 5395. This groups spiral stair applications into categories A – E, with A being a lowly used secondary domestic spiral and E being a widely used fully public spiral.
This document specifies the maximum height of each step, the minimum going (depth) of each step and crucially, to answer this question, the clear walking width. Logically, the more people who are going to be using the spiral, the larger the diameter and the more comfortable it will be to ascend. Click on the image on the right for a helpful table extract from the BS5395.