Types of Stairs

Generally, stairs are of the following types (Figure 20.1):

1. Straight stairs
2. Quarter turn stairs
3. Half turn stairs
4. Three quarter turn stairs  Figure 20.1 Different types of stairs
5. Circular stairs
6. Spiral stairs
7. Curved stairs
8. Geometrical stairs
9. Bifurcated stairs

Straight stairs

These are the stairs along which there is no change in direction on any flight between two successive floors. The straight stairs can be:

1. Straight run with a single flight between floors
2. Straight run with a series of flights without change in direction
3. Parallel stairs
4. Angle stairs
5. Scissors stairs

Straight stairs can have a change in direction at an intermediate landing. In case of parallel stairs, the stairs require a complete reversal of direction. In case of angle stairs, the successive flights are at an angle to each other. Scissor stairs are comprised of a pair of straight runs in opposite directions and are placed on opposite sides of a fire-resistive wall.

Quarter turn stairs

They are provided when the direction of flight is to be changed by 90°. The change in direction can be effected by either introducing a quarter-space landing or by providing winders at the junctions.

Half turn stairs

These stairs change their directions through 180°. It can be either ‘dog-legged’ or ‘open newel type’. In case of dog-legged stairs, the flights are in opposite directions and no space is provided between the flights in plan. On the other hand, in open newel stairs, there is a well or opening between the flights and it may be used to accommodate a lift. These stairs are used at places where sufficient space is available.

Three quarter turn stairs

This type of stairs change their directions through 270°. In other words, direction is changed three times with its upper flat crossing the bottom one. In this type of construction an open well is formed.

Circular stairs

These stairs, when viewed from above, appear to follow a circle with a single centre of curvature and large radius. These stairs are generally provided at the rear of a building to give access for servicing at various floors. All the steps radiate from a newel post in the form of winders. These stairs can be constructed in stone, cast iron or RCC.

Spiral stairs

These stairs are similar to circular stairs except that the radius of curvature is small and the stairs may be supported by a centre post. Overall diameter of such stairs may range from 1 to 2.5 m.

Curved stairs

These stairs, when viewed from above, appear to follow a curve with two or more centres of curvature, such as an ellipse.

Geometrical stairs

These stairs have no newel post and are of any geometrical shape. The change in direction in these stairs is achieved through winders. The stairs require more skill for its construction and are weaker than open newel stairs. In these stairs, the open well between the forward and the backward flights is curved.

Bifurcated stairs

These stairs are so arranged that there is a wide flight at the start which is subdivided into narrow flights at the mid-landing. The two narrow flights start from either side of the mid-landing. Generally, these stairs are more suitable for public buildings.