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Stair

It is defined as a sequence of steps and it is provided to afford the means of Ascent and Descent between the floors or landing. The apartment or room of a building in which the stair is located is known as a staircase

The Other means of transportation between the floors of a building are lifts, ramps and moving stairs.

Some important terms related to stairs

Flight- This is defined as an unbroken series of steps between the landings.

Landing- The horizontal platform between two flights of stairs is known as the landing. A landing facilitate change of direction and taking rest during the use of stair

Nosing- The projecting part of the trade beyond the face of the riser is known as nosing.

Rice- This is the vertical distance between two successive treads.

Soffit- The undersurface of a stair is known as soffit. It is generally covered with the ceiling for finished with plaster.

Tread- The horizontal upper portion of a step is known as a tread.

Waist- The thickness of the structural slab in case of an RCC stair is known as a Waist.

Ramp- A Ramp is a sloping surface and it is adopted as a substitute for stairs for easy connection between the floors. The important features of a ramp are as follows

  • The usual slope of Ramp is 1 in 15 but a slope of 1 in 10 is desirable.
  • The flooring of the Ramp should be of non-slippery material.
  • The shape of the Ramp need not be straight it may be of any geometrical shape.
  • The ramps should be provided with handrails on both sides.
  • The ramps should lead directly to the outside open space on ground level.

Types of stairs

There are many different types of stair.

  1. Straight stairs
  2. Turning stairs
  3. Circular or helical or spiral stairs
  4. Geometrical stairs

1- Straight stairs- In case of straight stairs all steps lead in one direction only. It may consist of one or more flights and they are used when the space available for the staircase is long but narrow in width.

2- Turning stairs- In this flights take turns. The most common types of turning stairs are described below

A- Quarter turn stair- A stair turning through one right angle is known as a quarter-turn staircase if a quarter-turn staircase is branched into two flights at a landing it is known as bifurcated stairs.

This type of stair is commonly used in public buildings near their entrance hall.

B- Half turn stairs- A stair turning through two right angles is known as a half-turn stair. A half-turn stair may be of dog-legged type or open newel type.

In case of dog-legged stair the flight runs in opposite directions and there is no space between them in the plan.

In the case of an open newel stair, there is a well or hole or opening between the flights in the plan. This well may be rectangular or of any geometrical shape.

C- Three-quarter turn staircase- Stair turning through 3 right angles is known as three quarter turn staircase. In this case, an Open Well is formed. This type of stare is used when the length of the staircase is limited and when the vertical distance between the two floors is quite large.

3- Circular or helical or spiral stairs-  In this type of stair the steps radiate from the center and they do not have either any landing or any intermediate newel post.

A spiral stair may be constructed of cast iron, mild steel, or concrete usually the structural design and construction of a spiral stair are complicated in nature.

Spiral stairs are useful where the space available is limited and where the traffic is less.

4- Geometrical stairs- These stairs have any geometrical shape and they require no newel posts. It requires considerable skill. It is found that a geometrical stair is weaker than an open newel stair.

Moving stairs

These stairs are known as escalators or ever-moving flights of electrically operated stairs. These escalators are kept in motion by a revolving drum.

Essential Parts- An escalator consists essentially 3 parts

  1. Steel trussed
  2. Framework, handrails
  3. Endless belt with steps.

Stairs of different materials

  1. Stone stairs
  2. Wooden or timber stairs
  3. Brick stairs
  4. Metal stairs
  5. RCC stairs

The choice of the type of material to be adopted for the construction of the stair will depend on the availability of funds, qualities desired use of the stair, durability expected architectural effect required, etc.

1- Stone stairs- These stairs are used for warehouses, workshops, etc. The stones to be used for the construction of stairs should be hard and non-absorbent and they should possess enough resistance to the action of fire.

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