A staircase in a building is provided to facilitate vertical movements. At present there are many types of staircase being used in buildings and each of them has its own use and merits as well as demerits.
Types of stairs are described below-
- Straight stairs
The straight stairs are one which do not have any turn till the end and so does lead to one direction only. Many a times it is not possible to provide straight stairs due to lack of space.
- Turning stairs
The turning staircase are one in which there is at least one turn in their direction before landing. They are broadly used and has following subtypes-
- Quarter turn stairs
In case of quarter turn stairs direction is changed once by right angle at once. If a quarter turned stair is branched into two flights at landing as shown below then it is called bifurcated stair. These are most common and wide application in public buildings.
- 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 as shown below.
In case of dog legged staircase, the flights run in opposite directions and there is no space between them in plan.
- Three Quarter turn stairs
When a staircase turns at the right-angle times till its landing it is called three quarter turn stairs.
- Quarter turn stairs
- Circular or Helical or spiral stairs
While the concern is of circular stairs the, the steps radiate from the centre and they do not have any landing or any intermediate newel post1.
- Geometrical stairs
These types of staircase could possess any geometrical shape and they do not require any intermediate newel post.
Requirements of a good stair-
- In order to make ascent and descent easy, the treads and riser should be properly designed.
Following thumb rules must be satisfied.
- (Rise in cm) + (going in cm) = 40 to 45
- (Rise in cm) * (going in cm) = 410 to 450
- 2 times rise in cm + going in cm = 60 approximately
- Rise = 140 mm
Going = 300 mm Standard
- The inclination of a stair should be 30 to 40 degree.
- Flight – It is not desirable to provide flight at more than 12 or maximum at 15 steps.
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