Staircase Basics, Design, Components, Types, and Safety Standards

Staircase

A stair is a set of stairs that are appropriately positioned to connect each floor of a building.

Staircase Basics, It may also be defined as an arrangement of treads, risers, stringers, newel posts, handrails, and balusters, so designed and constructed as to provide easy and quick access to the different floors, rendering comfort and safety to the users. The enclosure containing the complete stairway is termed a staircase

Staircase (NBC) National Building Code of India.

The minimum clear width (unobstructed by projections or handrails) of the staircase shall be as follows:

• Apartments Shared 1000 mm (Within each multilevel unit) Internal 800mm
• Auditoriums with a capacity of 1500 mm or less and 2000 mm or more
• Hospitals 2000 mm
• Cold Storage and Warehouses 1250 mm
• Buildings taller than four stories (1250 mm) (commercial or industrial) Suggested for various kinds of structures:
• Educational 2000 mm
• Residential 800 mm
• Cinemas with less than 500 seats: 1500 mm; theaters with more than 500 seats: 2000 mm
• Public Assembly is 2500 mm for capacities greater than 2500 occupants Note: For reduced-use staircases such as accesses to lofts, attics, and terraces, the minimum width shall be 600mm.
• The minimum tread shall be 250 mm excluding nosing and the maximum riser will be 175 mm for all buildings except for internal staircases of Apartments, which can be permitted up to 190 mm.
• Handrails shall be provided in all open staircases
• Handrails shall not be lower than 900 mm above the center of the tread.
• There can only be a maximum of 15 risers each flight.
• A staircase’s minimum headroom must be at least 2000 mm, measured vertically from the tread nosing to the soffit plane above.

Requirements of a good stair

Location: Its placement should guarantee that the stairs has enough light and ventilation. If possible, it should be located centrally so as to be easily accessible from the different corners of the building

Width of a stair: The situation and the reason for which a stair is provided determine its breadth. In a public building, where there is regular traffic of people using the stair-way, its width should be sufficient while in a residential building, it may just minimal. The usually adopted average value of the stair width for public and residential buildings is 1.8m and 90cm respectively.

Length of flight: There should be no more than 12 steps in a flight and no more than 3 steps for a pleasant stairway ascent.

Pitch of stair: To make the lengthy stairway less hazardous and exhausting to climb, landings should be added to make the pitch flatter. In general, the slope of stairs should never exceed 40 degrees and should not be flatter than 25 degrees.

Head room: There should be at least 2.14 meters of head room or the unobstructed space between the tread and the soffit of the flight directly above it.

Materials: The stair should preferably be constructed of materials that possess fire-resisting qualities.

Balustrade: The open well stairs should be provided with a balustrade so as to minimize the danger of accidents.

Landing: the width of the landing should not be less than the width of stairs.

Step proportions: The rise and tread of each step in a stair should be uniform dimensions throughout. The going and the rise of a step should be proportioned as to ensure comfortable access to the stairway.

Elements of staircase

1. Tread: The horizontal member of a stair, on which the foot is placed while ascending or descending. It is the horizontal separation between two risers that come one after the other. It is also known as the “Going”.
2. Riser: The vertical component that supports step on a staircase. The vertical distance between two consecutive treads is known as the “rise”.
3. Step: Riser and tread together from step.
4. Staircase: The volume (enclosure) where the stair is accommodated is called a staircase.
5. Stairway/ Stairwell: The space where the stair is housed is called the stairway.
6. Landings: It is the platform left between two flights for circulation and rest.
7. Flight: It is the series of steps between landings.
8. Winder: The trapezoidal tread is winder.
9. Nosing: It is the exposed edge of tread that is projected outwards.
10. Strings/ Stringers: The members receiving ends of step are strings.
11. Soffit: It is the underside of the stair.
12. Head room: It is the minimum clear distance between the tread and the overhead structure.
13. Handrail: It is the protecting member usually parallel to the string, for support while ascending or descending.
14. Baluster: The vertical infill member between the string and the handrail is called a baluster. A row of balusters surmounted by a handrail is known as the “Balustrade”
15. Pitch line or line of nosing: It is an imaginary line connecting the nosing of all treads in one flight. Pitch or slope is the angle made by the line with the horizontal.
16. Newel: It is the post-forming the junction of flights with landing or carrying the lower end of strings.

Types of staircases

The stairs could be made of cast iron, concrete masonry, or wood. Due to the risk of fire, wooden staircases are not safe. They are utilized, nevertheless, to gain access to little spaces on the upper floors of inconspicuous structures. Cast iron or steel stairs in the spiral forms were used commonly to reduce staircase area. Masonry stairs are also utilized in a lot of residential buildings. Stairs made of reinforced concrete are frequently found in all kinds of buildings.

Based on the shapes and method of construction stairs may be classified as:

1. Straight Staircase

Literally, as its name, it has no bends. It can fly in a straight line with no direction changes. The most popular and reasonably priced kind of staircase is a straight staircase. The design does not need any support, an attachment at the bottom and the top is all it needs. The bonus point of this design is its ease to install of railings and handrails. Because it is not steep, it is easy to maneuver on and suitable for both young children and the elderly. Because of its straightforward appearance, it works well with minimalist designs.

2. Dog Legged Stairs

There is a 180° bend in between the two straight flights. They are frequently utilized to provide floor-to-floor access.

3. Well or Open-newel Stairs

It differs from dog-legged stairs such that in this case there is a 0.15 m to 1.0 m gap between the two adjacent flights.

4. Geometrical Stair

With the exception of the curving well formed between the two neighboring steps, this sort of stair is comparable to an open newel stair. The hand rail provided is continuous.

5. Spiral Stairs

These stairs are commonly used as emergency exits. It is comprised of a central post that holds up a spiral-shaped set of steps. There is a continuous handrail at the top of the steps. These steps are installed in areas with very little room for staircases. Cast iron, steel, or R.C.C. is used for building these stairs.

6. Turning Stairs

A part from dog-legged and open newel-type turns, stairs may turn in various forms. They rely on how much room there is for stairs. Some examples of such turned stairs are bifurcation stairs, quarter turned stairs, and half turned stairs with few feet between.

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