Basics in Building Construction

Building Components And Types

Lesson 22 and 23 : Stairs

Technical Terms

The common technical terms used in stair construction are

1. Step: Step is a combination of tread and riser and permits a person to ascend or descend from floor to floor.


2. Tread: This is the horizontal surface of a step where the foot is kept while ascending or descending.


3. Riser: The vertical distance between the surfaces of two successive treads. Or the vertical face of each step in a flight of stairs.


4. Nosing: The projected portion of a tread beyond the face of the riser is called as nosing. The projection usually does not exceed 25 mm and should be rounded off smoothly. Nosing imparts architectural beauty to the stair.


5. Going: The clear horizontal distance between two successive risers is called going.


6. Flight: A series of steps without any break such as landing is called as a flight.


7. Landing: In order to provide relief while ascending or descending and to change the direction of a stair, a portion of stair is made flat without steps.


1. Halfpace landing: The landing between two flights of steps that make a 180 0 turn, its width is usually double that of the stairs plus the stairwell.


2. Quarterpace landing: The landing between two flights of stairs making a 90 0 turn, its width is usually that of the flight of stairs.


8. Line of Nosing: This is an imaginary line joining the edges of nosings.


9. Pitch or slope: The subtending angle between the line of nosing with the horizontal is the pitch or slope.


10. Soffit or Plancer: Underside of the stair is called as soffit.


11. Head room: The clear vertical distance between the tread of a step and the soffit of the above flight, ceiling or landing immediately over it is called as head room. The head room should not be less than 2.15m.


12. Spandrel: The triangular portion beneath the lower flight at ground floor is called as spandrel.


13. Walking line or line of travel: An imaginary line along which a person using a stair walks while ascending or descending is called as line of travel. Generally it is at a distance of 40-45 cms from the hand rail.


14. Stair: A series of steps connecting one floor with other immediately above is called as stair. Stairs if located in a separate room, such room is called as stair case. Stair cases should about the outer walls of a building to draw the benefit of natural lighting and ventilation.


15. Hand rail: Hand rails are provided to render assistance to the user of the stair way while ascending or descending. They are supposed on frame work of balustrades and run between two newels, parallel to the line of nosing. Previously hard wood is used for making hand rails, since it can be carved to various architectural shapes. Now a days, aluminum and steel hand rails are becoming popular since they are strong , long lasting and cheap as compared to wood.


16. Newels or Newel posts: These are wooden or metallic posts which support the hand railing at ends. They are provided at beginning and at the points where the hand rails changes its direction. In case of wooden stairs the upper end which is moulded round is called as drop.


17. Strings or stringers: These are the inclined members of a stair and support the steps. In case of an RCC stair string beam is provided at the middle or at ends of the flight running parallel to it.


18. Baluster: A vertical wooden member which supports the hand railing.


19. Balustrade: A frame work of baulusters.


20. Head Room: It is the minimum clear vertical distance between the tread and overhead structure (i.e. ceiling)


21. Run: It is the total length of stairs in a horizontal plane, including landings.