Whenever a building is construct, arrangement has to be done for going up either at the roof of ground floor or floor of the first floor and so on and also for coming down. This aim is achieve by providing a stair which is nothing but a sequence of steps provide to afford the means of ascent and descent between the floors or landing provide in the buildings. The enclosure or the room of the building in which stair is locate is refer as stair case and space occupy by stair is known as stair way.

Straight flight stairs

The stairs having no change in direction on any flight between two successive floors are straight flight stairs. Such stairs may or may not have any landing between the flights. Landing becomes a necessity if the ascent is steep.

Straight flight stair is use in places where restrict width is available for the stair and also where the height between two successive floors is less. Its most obvious use is to form an access to entrance, porch or portico.

Quarter turn stairs

The stairs which turn through 90 degrees either to the left or right are known as quarter turn stairs.

The change in the direction of flight may be obtain either by providing a quarter space landing or by providing winders. Such stairs may be newel quarter turn stairs or geometrical quarter turn stairs.

Half turn stair

The stairs which turn through 180 degrees are half turn stairs. A quarter space or half space landing or winders may be use.

Half turn stairs may be of any one of the following types :

• Dog-legged stairs.
• Open well stairs or open newel stairs.

Dog-legged stairs

In this case, the flights are in opposite directions and no space is provide between the flights in plan. It is suitable and is conveniently use when the width of the staircase is restrict and only two flights can be accommodate. The flights have abrupt turn between them. At the change of direction, a level, landing is place across the flights.

Open well stair or Open newel stair

The stairs which have clear space between two successive flights ( i.e., backward and forward flights ) are refer as open well or open newel stairs. The clear space may be in the form of opening or a well and it may or may not be use for providing a lift and for providing lighting facilities from the top.

Such stairs are use at place where sufficient space is available because these need greater width. Open well stairs give a better appearance.

Geometrical stairs

The stairs provide with winders for bringing a change in its direction are known as geometrical stairs. Such stairs have no newel post. In these stairs, open well is curve between two successive flights.

Bifurcated Stair

The stairs which bifurcate into two parts after the first flight, are known as bifurcated stairs. In such cases, there is a wide flight at the start and this flight is sub-divide into narrow flights at the mid-landing. These narrow flights ( 2 in numbers ) start from either side of the mid-landing provide for changing the direction. Such stairs are more suitable for modern public buildings, cinemas, railway foot bridges etc.

Spiral stairs

The stairs whose steps are arrange in spiral form are known as spiral stairs. It consists of a central post fix with steps around it in a spiral form. The diameter of such stairs varies from 1 m to 2.5 m. Spiral stairs are similar to circular stairs except the radius of curvature which is small in this case and more in circular stairs.

These stairs are suitable where a very small space is available for the staircase and traffic also is too less.

Circular stairs

The stair provide in a circular staircase in known as circular stair. Such stairs when view from above appear to follow a circle with large radius and single centre of curvature. Circular stairs are provide at the rear of a building to give access for serving at various floors. The steps radiate from newel post in the form of winders. The strings and the handrails are continuous.

Helical Stairs

It looks excellent but its design is complicate and construction is very difficult, steel is provide for resisting bending stresses, shear stresses and torsional stresses.

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