If there are no side walls, it can be fastened between the structure and the floor to stiffen the staircase strengthening its solidity; it is made of anodised aluminium like the loadbearing structure.
Do I need to comply with building regulations?
All spiral staircases whether new or replacement need to comply with the UK building regulations - there are also special requirements for Spiral Stairs and Space Saver stairs which are detailed in BS5395-2, the British Standard which applies to staircases of this type, BS5395-2 is referred to in building regulations as the general standard for spiral staircases and helical stairs.
Spiral Staircase Dimensions under Building Regs BS5395-2
One aspect of UK building regulations is that it refers to British Standard BS5395-2 for most aspects of spiral staircase dimensions.
Generally the two key tread dimensions are:
Clear tread width - measured between the INSIDE of the handrail and the centre column - this should be a MINIMUM of 600mm
Tread riser height - this should be a MAXIMUM of 220mm to meet UK building regulations. Generally if you divide the total finished floor to finished floor height of your room (NOT floor to ceiling!) by 220mm this will give you the minimum number of risers in your staircase to meet building regs. If the result is not a whole number then you need to adjust to the next whole number above - e.g. if the result is 13.5 risers, you actually need 14 risers.
Please note most spiral staircases with height adjustment will have a quoted range of adjustment up to 230mm per riser - if you need to use a riser height above 220mm for any reason then we suggest you first contact your building control department for clearance.