Staircase Design | How to Calculate Number of Riser and Treads of Staircase?

 

Stairs are used to move from floor to floor. Stairs allow access and communication between floors in multi-story buildings. The room or space between which a stair is located is known as the staircase. 

It should therefore be covered with fire-resistant walls, floors, roofs and doors. It should be designed to carry certain loads used for the design of floors. Various materials such as wood, brick, stone, steel or reinforced cement concrete can be used for stair construction.

Important points to consider when planning the staircase design calculation

Before starting please make a note of the Minimum Specification

·       Maximum height of the riser should be 150 (6”) to 200 (8”) mm.

·       Minimum length of tread should be 250 (10”) to 300 (1’) mm in length.

·       The length of the step should be at least 600 mm.

·       Handrail height should be at least 1 meter.

·       Width of the landing slab should be at least 1000 mm for the staircase.

·       The minimum vertical space or headroom above any step or the stair should be 2 m.

·       Generally, the number of risers in a flight should be restricted to 12.

·       For all parallel steps the respective dimensions and riser must be identical on the continuous site of a building.

·       The minimum vertical space above any staircase or headroom should be 2m.

·       Generally, the number of risers per flight should be limited to 12.

·       The width of the stairs should not be less than 850 mm. The standard width of any staircase can range from 1.1 to 1.6 m. Large wide stairs can be used in large utility buildings such as malls, cinemas and shopping centres.

Note - this is not a fixed rule, many factors will be considered in the design of the staircase.

 

When designing the dimension of any staircase to find out first, is rise and tread of the stairs and their numbers.

GIVEN DATAS (EXAMPLE)

Total Clear Distance Between two-floor (A) = 10’3” (3.12m)

 

Total Width of one flight or Distance between the first riser to last riser (B) = 6’ (1.8m)

 

(For Your Understanding see below picture f staircase)

 

First step to choose riser size,

 

Size of riser = 6” (inch) (Range of riser = 6”to 8”)

                   = 150 mm (Range of riser = 150mm to 200mm)

 

 

Number of Riser = Clear Distance between two floors (A) / Size of Riser

                           = (3.12/ 0.15)

                           = 20 nos. (10 for first flight and 10 for second flight)

 

Now, we will calculate the size of tread,

 

(We know that for any stair numbers of tread for any single flight are one less than several rises.)

 

Nos of threads on single flight = Nos. of Rising of single flight – 1

                                                 = 10 – 1

                                                 = 9 nos.

 

So, Size of Tread = Total width of Stair / Nos. of Thread

 

                            = 1.8 / 9

 

  Size of Tread = 0.2 – 200mm

 

(This dimension can be changed as per types of the stair)

 

So, Data

 

1) Size of Rise = 150mm – 6”

 

2) Number of Riser on single flight = 10 nos.

 

3) Width of Tread = 200mm – 8”

 

4) Number of Tread = 9 nos.

 

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