Staircase

1.1: Introduction

      A staircase is a means of providing access from the one-floor level to another. It is a means for vertical circulation. Modern stairs with their handrails are designed with the main emphasis. Space/room for housing stairs is called staircase or the room or enclosure of the building where the stair is located is known as the staircase.

staircase

1.2: Necessity of staircase

1)Protect people from injury and facilitate access during movement from one level to another in a building.

2)Used for the purpose of safe ascent or descent.

3)Also used as a means of escape in case of fire.

1.3: Technical terminology

            Elements of the staircase are as follows:-

staircase

1)Tread

         The horizontal member of a stair, on which the foot is placed while ascending or descending. It is the horizontal distance between two successive risers. It is also known as the “Going”.

2)Riser

It is the vertical member of a stair that supports tread. The vertical distance between two consecutive treads is called “rise”.

3)Step

          Riser and tread together are called step.

4)Staircase

         The volume (enclosure) where the stair is accommodated is the staircase.

5)Stairway/stairwell

         It is the space where the stair is housed.

6)Landing

          Platform left between two flights for circulation and rest is landing.

7)Flight

        Series of steps between landings is flight.

8)Winder

          The trapezoidal tread is called winder.

9)Nosing

        The exposed edge of the tread, projected outward is nosing.

10)Strings/Stringers

          The members receiving ends of steps are stringers.

11)Soffit

       The underside of the stair is soffit.

12)Headroom

           Minimum clear distance between the tread and the overhead structure.

13)Handrail

Protecting member usually parallel to the string, for support while ascending or descending.

14)Baluster

          The vertical infill member between the string and the handrail. A row of balusters surmounted with handrail is known as the “Balustrade”.

15)Pitch Line

      An imaginary line connecting the nosing of all tread in one flight. Pitch or slope is the angle made by the line with the horizontal.

16)Newel

         Post forming the junction of flights with a landing or carrying the lower end of strings.

1.3: Types of Staircase

        Stairs can be classified under two headings:-

1)Classification based on materials

2)Classification based on shapes.

1)Classification based on materials 

       Based on the materials of construction stairs are as follows:-

a)Timber stair

b)Stone stair

c)Concrete Stair

d)Metallic Stair

e)Masonry stair

              The stairs may be built with concrete masonry, wood or with cast iron.  Wooden stairs are at high risk of fire. However, they are used in unimportant buildings to access small areas on the upper floors. Cast iron or steel stairs in the spiral forms were used commonly to reduce the area of the staircase. In many residential buildings, masonry stairs are also used. Reinforced concrete stairs are commonly used in all types of buildings.

2) Classification based on shapes

Based on the shapes stairs are classified as:-

a)Straight stairs

b)Well or open-newel stairs

c)Spiral stairs

d)Dog legged stairs

e)Geometrical stairs

f)Turning stairs

g)Helical etc

1.4: Design of the staircase

-Design procedure

            When the level difference between two floors (ceiling height plus the thickness of the floor slab are given:-

1) Assume the types of building and stair and accordingly the size of the riser(R).

2) Find the number of risers by NR=(level difference/size of the riser).

3) Find the number of treads by NT =(NR-1).

4) Assume the size of tread (T).

5) Assume the width of the stair.

6) Consider the size of landing (L)equal to the width of the stair.

7) Assume the entry space (E), generally equal to landing).

8) Find the total length of stair =(NT*T)+L+E.

9) Adjust the size of riser and tread if required.

Salient Points to be considered in Locating Stairs 

The following points should be considered in locating stairs in a building:-

(A) They must be located near the main entrance to the building.

(B) There should be easy access from all rooms without disturbing the privacy of the rooms.

(C) There should be a spacious approach.

(D) Good light and ventilation should be available.

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