Types of Stairs

Discussing different components of stair and their types.

1. Abhishek Singh Assistant Professor Department of Civil Engineering National Institute of Technology, Raipur

2. A stair is a set of steps leading from one floor of a building to another, typically inside the building. The room or enclosure of the building, in which the stair is located is known as staircase. The opening or space occupied by the stair is known as a stairway.

3. Step It is a portion of stair which permits ascent & descent. Tread It is the upper horizontal portion of step upon which the feet is placed. Riser The vertical portion between each tread on the stair . Handrail A handrail is a rail that is designed to be grasped by the hand so as to provide stability or support.

4. Baluster It is vertical member of wood or metal supporting the handrail. Newel post This is the vertical member which is placed at the ends of flights to connect handrail . Run It is the total length of stairs in a horizontal plane, including landings. Nosing It is the projecting part of the tread beyond the face of the riser.

5. String Or Stingers These are the sloping wooden members which support the steps in a stair .They run along the slope of the stair .

6. Usually 150mm riser and 280mm tread should be recommended for a good staircase . Minimum width of staircase: Residential=1m, Public=1.5m Minimum Headroom: The minimum clear headroom in any staircase shall be 2.2m Width of landing: The width of landing should not be less than the width of the stair. Handrails : As per IS: 4912-1968 a stair railing shall be provided with the vertical height not more than 85cm nor less than 75cm from the top rail to surface of tread.

7. Straight stairs These are the stairs along which there is no change in direction on any flight. It is used where stair case hall is long and narrow.

8. Turning stairs Turning stairs are sub classified as Quarter turn stairs Half turn stairs ( dog legged stairs) Three – quarter turn stairs Bifurcated stairs

9. Quarter turn stairs A stair turning through one right angle is known as quarter turn stair. The change in direction can be affected by either introducing a landing or by providing winders.

10. Half turn stairs ( dog legged stairs) It consists of two straight flights of steps with abrupt turn between them. A level landing is placed across the two flights at the change of direction. This type of stair is useful where the width of the staircase hall is just sufficient to accommodate two width of stair. Turning stairs

11. Three – quarter turn stairs A stair turning through right angles (270 degree) is known as three quarter turn stair. In this case an open well is formed. Turning stairs

12. Bifurcated stairs These stair are so arranged that there is a wide flight at the start which is further sub-divided into two narrow flights at the mid landing. The two narrow flight starts from either side of the mid-landing. Turning stairs

13. Continuous stairs This type of stairs neither have any landing nor any intermediate newel post. They are geometric in shape. These are may be of following types Circular stairs/Spiral stairs Helical stairs

14. Circular stairs/ Spiral stairs Circular stairs or spiral stairs are usually made either of R.C.C or metal, and is placed at a location where there are space limitations. These are not comfortable because of all the steps are winders and provides discomfort.

15. Helical stairs A helical stair looks very fine but its structural design and construction is very complicated. It is made of R.C.C in which a large portion of steel is required to resist bending, shear and torsion.