Correct Answer - Option 2 : 2 × Riser + Tread = 600 mm
Explanation:
Following thumb rules are commonly used for obtaining a satisfactory proportion of the tread and riser of a step:
i) (Rise in cm) + (Tread in cm) = 40 to 45
ii) (Rise in cm) × (Tread in cm) = 400 to 450
iii) (2 × Rise in cm) + (Tread in cm) = 60 ⇒ (2 × Rise in mm) + (Tread in mm) = 600 mm
iv) Take rise = 140 mm and going = 300 mm as standard.
In case of flight, number of treads = riser - 1
However, the general relationship between riser and tread is given by:
(2 × Riser) + Tread = Step Length
The following are the components of the staircase
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Components
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Definition
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Step:
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It is a portion of the stair which permits ascent or descent. A stair is composed of a set of steps.
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Tread:
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It is an upper horizontal portion of a step upon which foot is placed while ascending or descending.
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Riser:
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It is a vertical portion of a step providing support to the tread.
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Landing:
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It is a level platform at the top or bottom of a flight between the floors.
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Flight:
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This is an unbroken series of steps between landing.
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Rise:
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It is a vertical distance between two successive tread faces.
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Going:
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It is a horizontal distance between two successive riser faces.
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Nosing:
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It is the projecting part of the tread beyond the face of the riser.
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Scotia:
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It is a molding provided under the nosing to provide strength to the nosing.
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Soffit:
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It is the underside of a stair.
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Pitch or Slope:
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It is the angle which the line of the nosing of the stair makes with the horizontal.
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Strings:
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These are the slopping members which support the steps in a stair.
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Newel post:
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Newel post is a vertical member which is placed at the ends of flight to connects the ends of strings and handrail.
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Baluster:
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It is a vertical member of wood or metal, supporting the handrail.
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Headroom:
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It is the clear vertical distance between the tread and overload structure.
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