Height
The vertical distance between the lower floor and the upper floor.
Total run
Horizontal distance between the nosing of the first step and the nosing of the upper floor step.
Step
A horizontal surface supporting the user's foot.
Landing step
A step that forms an extension of the upper floor.
This enables the application of a overlap onto the last step.
It also facilitates the connection of the string and handrail to the upper floor.
Step height
The vertical distance between two step nosings.
The height of the step must be between 150 and 200mm (6 and 8").
Its ideal value is 175mm (7").
Going
Horizontal distance between two step nosings.
The going must be between 230 and 330 mm (9 and 13").
Its ideal value is 280 mm (11").
Angle
Determines the slope of the staircase.
The angle must be between 20 and 50°. Its ideal value is 30°.
Blondel's Law
G + 2H = 590 to 650mm
G + 2H = 23.2 to 25.6"
G: going
H: Step height
Formula created by French architect François Blondel (1618-1686) verifying coherence between the step height and the going.
The ideal value is 630mm (24.8").
Riser
Vertical section joining 2 consecutive steps.
Overlap
Part of the step that is covered by the next step up.
The overlap enhances the comfort of the staircase.
Step nosing
Protruding part of a step.
Stair width
Usable width of the staircase.
The stair width must be greater than and its ideal value is greater than or equal to 800mm (32").
String
An element that supports the staircase steps.
Flight
A sequence of steps.
Stairwell
An opening in the upper floor that accommodates the staircase.
Headroom
Distance between the ceiling and the walkline at the stairwell.
The headroom must be greater than 1900mm (75") and its ideal value is greater than or equal to 2100mm (83").
Landing
A horizontal surface wider than the steps.
It allows the user to take a rest or for a change in the direction of the staircase.
Walkline
An imaginary line representing the movement of the user.
It enables the determination of the going for turning staircases.
If the stair width is less than or equal to 1 m (40") then the walkline is in the centre.
If the stair width is greater than 1 m (40") then the walkline is 500mm (20") from the inner handrail.