A stair is a series of steps arranged in such a manner as to connect different floors of a building. Stairs are designed to provide as easy and quick access to different floors. A staircase is an enclosure which contains the complete stairway.
Generally stairs are of following types
Quarter turn stairs
Half turn stairs
Three quarter turn stairs
Bifurcated stairs and
Combination above types
1. 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 of following types.
Straight run with a single flight between floors
Straight run with a series of flight without change in direction
Straight stairs can have a change in direction at an intermediate landing. 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.
2. Quarter Turn Stairs
They are provided when the direction of flight is to be changed by 900. The change in direction can be effected by either introducing a quarter space landing or by providing winders at the junctions.
3. Half Turn Stairs
These stairs change their direction through 1800. 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.
4. Three Quarter Turn Stairs
These types of stairs change their directions through 2700. In other words direction is changed three times with its upper flight crossing the bottom one. In this type of construction an open well is formed.
5. Circular Stairs
These stairs, when viewed from above, appear to follow 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 R.C.C.
6. 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 center post. Overall diameter of such stairs may range from 1 to 2.5 m.
7. Curved Stairs
These stairs, when viewed from above, appear to follow a curve with two or more centre of curvature, such as ellipse.
8. 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.
9. 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 mid landing. Generally these stairs are more suitable for modern public buildings.
10. Combination of Different Types
Depending upon the requirement of a building or as per owner’s demand few of the types as mentioned above can be combined to design a new stair.