Types of Stairs

       The stairs may be built with wood, concrete masonry or with cast iron. Wooden stairs are not safe, because of the danger of fire. However they are used in unimportant buildings to access to small areas in the upper floors. Cast iron or steel stairs in the spiral forms were used commonly to reduce stair case area. In many residential buildings masonry stairs are also used. Reinforced concrete stairs are very commonly used in all types of buildings.

Based on the shapes stairs may be classified as:

(a) Straight stairs

(b) Dog legged stairs

(c) Well or open-newel stairs

(d) Geometrical stairs

(e) Spiral stairs

(f) Turning stairs.

(a) Straight Stairs: If the space available for stair case is narrow and long, straight stairs may be provided. Such stairs are commonly used to give access to porch or as emergency exits to cinema halls. In this type all steps are in one direction. They may be provided in single flight or in two flights with landing between the two flights 

(b) Dog Legged Stairs: It consists of two straight flights with 180° turn between the two. They are very commonly used to give access from floor to floor. Figure 8.36 shows the arrangement of steps in such stairs.

(c) Well or Open-newel Stairs: It differs from dog legged stairs such that in this case there is 0.15 m to 1.0 m gap between the two adjacent flights. Figure  shows a typical open- newel stair.

(d) Geometrical Stair: This type of stair is similar to the open newel stair except that well formed between the two adjacent flights is curved. The hand rail provided is continuous. 

(e) Spiral Stairs: These stairs are commonly used as emergency exits. It consists of a central post supporting a series of steps arranged in the form of a spiral. At the end of steps continuous hand rail is provided. Such stairs are provided where space available for stairs is very much limited. Figure 8.39 shows a typical spiral stair. Cast iron, steel or R.C.C. is used for building these stairs.

( f ) Turning Stairs: Apart from dog legged and open newel type turns, stairs may turn in various forms. They depend upon the available space for stairs. Quarter turned, half turned with few steps in between and bifurcated stairs are some of such turned stairs. Figure 8.40 shows a bifurcated stair.

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