Staircases

6.6
Also see:
BS 5395

6.6.8Design of steps

Steps shall be constructed to allow the safe use of the staircase. Issues to be taken into account include:

  1. pitch
  2. steps
  3. tapered treads and winders.

Pitch

The maximum angle of pitch of a stairway should not exceed:

  • 42° for private stairs

The dimensions for maximum rise and minimum going should meet national building regulations.

Private stairs should have a maximum rise 220mm and minimum going 220mm.

Staircases should be accurately located and fixed with the string at the correct angle to ensure all treads are level.

Stairs should be dimensioned so that the rise (R) and the going (G) is between 550mm and 700mm when using the equation: 2R + G.

Steps

In each flight:

  • treads should be level
  • the rise and going of steps should be equal
  • account should be taken of the thicknesses of screeds. Floor finishes that reduce the bottom rise by a maximum of 12mm are acceptable
  • the treads should overlap by a minimum of 16mm, where the riser is open
  • open risers should not have gaps greater than 100mm and are not permitted for common stairs.

Where stairs are open to the weather, designers should consider that grip may be affected by water or dust, and one of the following should be specified:

  • a non-slip finish
  • a non-slip insert to each tread.

Tapered treads and winders

The rise of tapered treads should be consistent throughout the staircase. The going should be:

  • uniform and no less than the going of the associated straight flight, measured from the centre line of the straight flight
  • a minimum of 50mm at the narrowest point.