Section 15(2) in Tamil Nadu District Municipalities (Hill Stations) Building Rules, 1993
(2)All stairs shall comply with the following requirements namely: -(a)Width of stairs: The clear width of the stairways shall not be less than 60 centimetres excluding the handrails.(b)Headroom: All stairways shall have at least 2.1 metres of clear headroom, measured perpendicularly from the nosing.(c)Treads and risers: Treads and risers shall be so proportioned that the sum of two risers and a tread width is not less than 60 centimetres and more than 62.5 centimetres. No riser shall be more than 17.5 centimetres and no tread width less than 25 centimetres. There shall be no variation in the widths of treads or the heights of risers in any one flight of stairs. No stairway should ordinarily be permitted cutting across any window. The surface material of stairs, treads and landings shall be such as not to involve undue danger of slipping.(d)Landings: No stairway shall have a height of more than 3.75 metres between landings nor less than two risers between consecutive landings; the landings shall have a dimension, not less than the width of stairs, measured in the direction of the run.(e)Rails: Stair shall have walls or well secured balustrades or guards on both sides. Handrails shall be placed not less than 75 centimetres and not more than 1 metre above the no sings of the treads.(f)Space under stairs: The space beneath any stairway built in whole or in part of combustible materials except handrails shall be left entirely open.(g)Ventilation for staircases: Every staircase shall be lighted and ventilated to the satisfaction of the Government from an open space.(h)Passage giving access to staircase: Every passage in a building in the ground floor shall, in no part, be less than the width of the staircase of such building to which it gives access:Provided that minimum width shall be equal to the width of such staircase plus one-half of the total width of the remaining staircases.
