Staircase Design Calculation – Riser & Tread Calculation

What Is a Staircase?

A staircase is an architectural feature that consists of a series of steps arranged in a way that allows people to move from one level to another in a building. Staircases can be found in homes, office buildings, public spaces, and many other types of structures.

Staircases can be designed in a wide range of styles and materials, from simple wooden stairs to elaborate, ornate staircases made from marble or other high-end materials.

The design of a staircase can play an important role in the overall aesthetic of a building, and can also impact the functionality and safety of the space.

There are several important factors to consider when designing or choosing a staircase. These include the intended use of the space, the amount of traffic that the staircase will need to accommodate, and the available space and budget.

Additionally, safety considerations such as the height and depth of each step, the location of handrails and guardrails, and the presence of any obstacles or hazards in the surrounding area must be taken into account.

Staircases can also offer a unique opportunity for creative expression, with many designers incorporating unique and interesting design elements such as curved or spiral shapes, intricate railings, and creative lighting features.

When properly designed and maintained, a staircase can be both functional and beautiful, adding value to space and enhancing the overall user experience.

Riser and Tread In Staircase

Riser

It is a vertical portion of a step providing support to the tread. 

Tread

It is the top portion or surface of the step on which the foot of the ascender or descender comes when going up or download by stair.

Read More: Staircase Reinforcement Calculation

Step: It is a portion of the stair that provides upward or downloads movement. A stair is composed of a set of steps. 

Tread: It is the top portion or surface of the step on which the foot of the ascender or descender comes when going up or download by stair.

Riser: It is a vertical portion of a step providing support to the tread. 

Landing: It is a level platform at the top or¢ bottom of a flight between the floors. 

Rise: A vertical Space between the top of the lower tread and the bottom of the upper tread faces. 

Going: It is a horizontal distance between two successive riser faces. 

Noisia: It is the projected portion of a tread beyond the face of the riser. 

Scotia: It is a molding provided under the nosing to provide strength to the nosing.

Soffit: it is a portion that is the underside of the stair.

Pitch or Slope: It is the angle that the line of the nosing of the stair makes with the horizontal.

Flight: This is an unbroken series of steps between landings.

Strings or Stringers: These are the slopping members who support the steps in a stair.  

Nevel post: It is a Vertical member of the stair which is located at the end of each flight to connect the ends of strings and handrails.  

Baluster: It is a safety member of the stair which is made of wood or metal, supporting the handrail.

Headroom: It is the clear vertical distances¢ between the tread and overload structure.

Read More: Types Of Stairs In Civil Engineering

Important Point to Consider Design of Staircase Calculation & Tread and Riser Calculation

Before starting please make the below assumptions

• The minimum height of the riser is 6” inches.
• The minimum tread width is 9” inches.

(Note – This is not a fixed rule, according to the type of building, use of the building and many other factors affect the size of the rise and tread for stairs.)

For Example, in hospitals, the rise may be 5″ because the staircase is mostly utilized only by ill or sick people who have to climb without using their full energy. So the riser may be shortened for easy access. The tread also should be wider enough.

The reason we are providing 10” inches for tread is every person will wear a slipper which may be a maximum of 10” for an average adult person based on that we are making tread space 10” inches minimum.

General Guidelines for Design of Staircase Calculation

The following are some pointers to be considered while doing the design of the staircase calculation:

• The respective dimensions of the tread and riser for all the parallel steps should be the same on the consecutive floor of a building.

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

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

• The width of the stair should not be less than 850 mm. The standard width of any stair may be between 1.1 to 1.6 m. In public-use buildings like malls, cinemas, and shopping centers larger width of stairs can be used.

How to Calculate Riser and Tread Dimensions

While planning any stair important dimension to find out first is the rise and tread of the stair and their numbers.

Before finding out rise and thread fix the following points,

Total Clear Distance Between two-floor (A) = 10’6” (3.20m)

Total Width of one flight or Distance between the first riser to the last riser (B) = 1.80m

(For a Better Understanding see fig. 1)

Stair Tread Calculation

First of all, decide the size of a riser,

Riser Size = 7” (inch) (Range of riser = 6”to 8”)

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

                      = (10’6”/ 7”)

                      = 18 nos. (9 for the first flight and 9 for the second flight)

Stair Riser Calculation

Now, we will calculate the size of the tread,

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

Riser Tread Formula

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

                                                      = 9 – 1

                                                      = 8 nos.

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

                            = 6’ (72”) / 8  

  Size of Tread = 9”

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

Final Data:

1) Size of Rise = 7”

2) Number of Risers on single flight = 9 nos.

3) Width of Tread = 9”

4) Number of Tread = 8 nos.

Wrong formula of tread = riser + 1

Conclusion

In conclusion, the design of a staircase is an important consideration for any building or structure, both from a functional and aesthetic perspective.

Two critical aspects of staircase design include the calculation of the staircase dimensions, including the riser height and tread depth, and the overall design of the staircase, including the selection of materials, shape, and style.

Calculating the dimensions of a staircase requires careful consideration of several factors, including the height of the space, the intended use of the staircase, and the applicable building codes and regulations.

Riser height and tread depth are critical dimensions that impact the safety and usability of the staircase and must be carefully calculated to ensure that the staircase is safe and functional for all users.

Additionally, the design of the staircase can impact the overall look and feel of a space, with many designers incorporating unique and interesting design elements to enhance the aesthetic appeal of the staircase.

The selection of materials, such as wood, metal, or glass, can also play a role in the overall look and feel of the space, as well as the durability and maintenance requirements of the staircase.

Overall, the design of a staircase requires careful consideration of both the functional and aesthetic aspects of the space and should be approached with careful attention to detail and adherence to applicable building codes and regulations.

When properly designed and executed, a staircase can be a beautiful and functional addition to any building or structure.

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