Stair is the means of vertical transportation between the floors. It should, therefore be designed so as to provide easy, quick and safe mode of communication between the floors. The general requirements which a stair fulfill are
Location: (i)It should be so located as to provide easy access to the occupants of the building. (ii) It should be so located that it is well lighted and ventilated directly from the exterior.(iii) It should be so located as to have approaches convenient and spacious.
Width of stair: It should be wide enough to carry the user without much crowd or inconvenience. Width of stairs depends upto its location in the building and the type of building itself. In a domestic building, a 90 cm wide stair is sufficient while in public building, 1.5 to 1.8 m width may be required.
Length of flight: From comfort point view, the number of steps is not more than 12 and not less than 3.
Pitch of Stair: The pitch of long stair should be made flatter by introducing landings to make the ascent less tiresome and less dangerous. In general the slope of stair should never exceed 40 0 and should not flatter than 25 0 .
Head Room: The clear distance between the tread and soffit of the flight immediately above it should not be less than 2.1 to 2.3 m, so that even a tall person can use the stair with some luggage on its head.
Balustrad: Open well stair should always be provided with balustrade, to provide safety to the users. Wide stair should have hand rail to both the sides.
Step dimensions: The rise and going should be of such dimensions as to provide comfort to the users. Their proportion should also be such as to provide desirable pitch of the stairs. The going should not be less than 25 cm , though 30 cm going is quite comfortable. The rise should be between 10 cm (for hospitals etc.) to 15 cm. The width of landing should not be less than the width of stair.
Materials of construction: The material used for the construction of stair should be such as to provide (i) sufficient strength, and (ii) fire resistance.
Landing: The width of landing should not be less than the width of stair.
Winder: The introduction of winder in stair should be avoided as far as possible. They are liable to be dangerous and involve extra expense in construction. They are difficult to carpet and are especially unsuitable for public buildings. Where the winders cannot be dispensed with, they should preferably be provided near the lower end of the flight. Instead of quarter space landing three winders may be used and for a half-space landing five winders or four radiating risers may be adopted.
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