Wednesday - September 13, 2023
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Stair | Properties & Technical Terms of Stairs

Stair

  • A stair may be defined as a series of steps suitably arranged to connect different floors of a building.
  • The room or enclosure of the building in which the stair is located is called a staircase.
  • The opening space occupied by the stair is called a stairway.
  • In a residential building, the stair should be centrally located to provide easy communication to all the rooms.
  • During public buildings, stairs should stand located near each entrance.
  • That is built up of timber, bricks, stones, steel either RCC.
Properties of Stair, Technical Terms of Stair,  Requirements for good Stairs, Trade & Rise proportion of Stairs, A stair series of steps,

Technical Terms of Stair

  • Steps:- Some portion of a stairway consisting of the tread also riser which permits ascent about descent from one floor over another.
  • Tread:- This horizontal upper part of a step on which the pad is placed in
    ascending either descending stairway.
  • Riser:-  Some vertical portion of a step giving support to tread.
  • Flight:– Each series of steps without either platform about the landing.
  • Landing:- A platform or resting place provided between two flights.
  • Nosing:- The outer projecting edge of a tread is termed nosing. Nosing is usually rounded to give a good architectural effect to the treads.
  • Winders:- Those are reducing steps that are provided during changing the direction of a stair.
  • Soffit:- It is the undersurface of a stair.
  • Handrails:- It is supported on balustrades and usually runs parallel to the slope of stairs.
  • Baluster:- It is a wooden, metal or masonry vertical member supporting a handrail.
  • Newel:- It is a wooden or metallic post supporting the handrail and is usually provided at the hand, foot or at points where the balustrade changes its direction.
  • Pitch or slope:- It is the angle which the line of the nosing of the stair makes with the horizontal.

Requirements for good Stairs

Location

  • It should be located such that sufficient light and ventilation will come in a stairway.
  • If possible it should be located centrally to be easily accessible.

Width of a Stair

  • The width of a stair varies with the situation and the purpose for which it is provided.
  • In a public building, where there is regular traffic of people, its width
    should be sufficient.
  • A residential building may be just the minimum.
  • The usually adopted average width for public and residential buildings is 1.8 m and  90 cm respectively.

Length of Flight 

  • For a comfortable ascent, the number of steps in a flight should be restricted to a maximum of 12 and a minimum of 3.

Pitch of Stair

  • The slope of the stair should never exceed 40° and should not be flatter than 25°.

Materials

  • Some stairs should preferably last constructed of materials that maintain fire-resisting qualities.

Landing

  • The width of each landing should not be less than the width of the stair.

Step proportions:-

  • The rise also treads of each step in a stair should move of uniform dimensions completely.
  • Number of risers = Total height of floor / Height of riser
  • Number of trade= Number of risers – 1
Properties of Stair, Technical Terms of Stair,  Requirements for good Stairs, Trade & Rise proportion of Stairs, A stair series of steps,

Trade & Rise proportion of Stairs

  • The size of a tread and riser varies with the situation of the stair and the purpose for which it has to be provided.

In general, these following thumb rules remain considered

  1. Going in cm * Rise in cm == 400 into 410 approx
  2. Going in cm + (2 x Rise in cm) == 60 approx
  • Adopt the standard size of going and rise to 30 cm and 14 cm
  • For residential buildings- Trade = 250 mm to 300 mm or Rise = 150 to 180 mm
  • For public buildings- Trade = 270 mm to 300 mm or Rise = 130 to 160 mm

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