Stairs is set of steps or flight leading from one floor to another. It is designed to provide easy and quick access to different floors. The steps of stair may be constructed as a series of horizontal treads and enclosed space between treads known as riser. The part of building containing a stairs known as staircase.
Straight Flight Stairs
Geometrically stairs constructed in many shapes according to space availability categorized as:
1. Straight Flight Stairs.
2. Half-turn or dog legged stairs.
3. Open Well Stairs.
4. Quarter Turn Stairs.
5. Spiral Stairs.
6. Circular Stair.
7. Curved or Elliptical Stair.
Materials for Construction of Stairs :
Materials most commonly used in the construction of Stairs are
- Stone,
- Timber,
- Steel and
- RCC.
Essential Requirements of Stairs :
Comfortable stairways can be designed in relation to the average human figure. During design process, we must considered things such as:
- Dimensions of an average person,
- Average comfortable walking stride,
- Fixing the gradient or pitch of the Stairs,
- Height of hand rail and minimum head room.
A well-designed stairs should have easy assent and the proportions of treads and risers should be going plus twice the rise. Following things are to be considered for easy and comfortable use of stairs.
1. Width of Stairs
- Minimum width of stairs, for single-family residential house should be kept 75 cm and in any case if the number of users is more than 10 than minimum width of stairs should be 95 cm.
- Minimum width of stairs, for two or more family residential house should be kept 100 cm and in any case if the number of users is more than 10 than minimum width of stairs should be 125 cm.
- For hotels, offices, educational buildings, theaters, cinema halls the minimum width of stairs should be 1.5 meters.
- For institutional buildings and hospitals etc minimum width of stairs should be 2 meters.
Note:
a. The width of landing should be more or at least be equal to the steps.
b. Where the number of users exceeds 300, it is preferable to provide two or more staircase.
2. Slope of Stairs
- Minimum slope of stairs with horizontal should be 26 Degree.
- Maximum slope of stairs with horizontal should be 45 Degree.
- Ideal and normally kept slope of stairs with horizontal should be 30 Degree.
3. Tread of Stairs
- Minimum width of tread for residential building should be 250 mm.
- Minimum width of tread for residential building and small commercial units should be 200 mm in special case due to non-availability of space.
- Minimum width of tread for non-residential building should be 300 mm.
4. Riser of Stairs
- The maximum height of riser for residential building should be 190 to 200 mm.
- The maximum height of riser for non-residential building should be 150 to 170 mm.
5. Head room
The minimum clear headroom in stairs should be 2.1 to 2.2 meter for easy movement of large furniture.
6. Hand Rail
Provision for handrail should be made at a comfortable height. The height of handrail should not be less than 800mm and not more than 900mm.
7. Provision of light
The stairs should be well lighted and have two-way electric switches should be provided at the head and foot of the stairs.
8. The steps of stairs should be of same length width and height in size otherwise it would lead to accidents.
9. It is better to have a gate at the top or at the bottom of stairs for safety and security reasons.
10. The space between the supports of hand rail in houses should not more than 250 mm to avoid any accidental fall especially for kids.
11. The maximum height of one flight should not more than 2.4 meters.
12. The maximum numbers of steps should not more than 15 and landing should be provided after 15 steps for comfort while moving up and down the stairs.
13. Nosing must be provided on treads during flooring to enhance the width of tread.
14. The riser should make obtuse angle with tread to enhance the width of tread.
15. The floor of stair steps should not be slippery and have groves in case of cement concrete floor.
16. Provision of natural light and ventilation should be made in stairs.
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