A series of steps which provide access from one floor to another is called a stair.
Stair Case :
The part of building accommodating the stair is known as stair case.
Important Technical Terms :
The combination of a tread and a riser supported by a string is called step.
· Tread :-
The horizontal top surface of a step on which foot is placed while going up or coming down a stair is known as tread.
· Riser :-
The vertical face of a step is called riser.
· Going or run :-
The horizontal distance between any two adjacent risers in a stair is called going or run.
The vertical distance between any two adjacent treads in a stair is called rise.
· Nosing :-
The projecting edge of a tread beyond its riser in a step is called nosing. The line joining nosing of all steps in a flight is known as Line of nosing.
· Pitch or Slope :-
The angle between the line of Nosing and the floor or landing is called pitch or slope of a stair.
· Hand Rail :-
As inclined member at a convenient height projecting above steps of a stair to provide assistance and safe-guard to the users is called hand rail.
· Balusters :-
The vertical members provided in between the steps and the handrail are balusters. These members act as intermediate support to the hand rail.
· Newels or Newels posts :-
The post provided at the bottom, top and all the turning points in a stair to support the hand rail are known as newels or newel posts.
· Soffit :-
The under surface of a stair is called soffit.
· Winder :-
A step of non-uniform width is known as winder. This type of step is usually triangular in plan.
Such steps are only provided for changing the direction of a stair and should be avoided as far as possible since they are very dangerous for quick movement of user.
· Landing :-
The horizontal platform provided in between any two flights of a stair is called landing.
the landing which provide 90o turn in the layout of a stair is known as quarter space landing.
If the turn is 180o , it is called half-space landing.
A series of steps without any break in between is known as flight.
· Head Room :-
The height between the line of nosing to the soffit of a flight or ceiling room immediately above is called head room.
· Width of a Stair case:-
The width of enclosure accommodating the stair in building is called width of stair case. It depend upon the layout and width of the stair.