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How to Calculate Number of Riser and Treads of Staircase

A staircase provides easy access from floor to floor. A staircase is a room or space that contains stairs. Stairway Design Calculation is necessary before constructing stairs to determine their risers and tread positions.

Buildings with multiple floors have staircases for access and communication. Fires spread from floor to floor with the help of these paths.

As a result, the structure must be protected by fire-resistant walls, floors, and ceilings. In the same way that floors are designed to carry specific loads, the frame will have to carry certain loads. Stairs can be built from a variety of materials such as timber, bricks, stone, steel, or reinforced cement concrete.

Tread: As you go up or down stairs, you place your foot on the top portion of the step is called Tread.

Riser: Step treads are supported by this vertical portion is known as Riser.

Points to Consider When Calculating Tread and Riser

The reason for 10 inches of tread is that everyone wears slippers that may be up to 10 inches in length for an average adult person, so you want to make sure the treads are no shorter than 10 inches in length.

A 5-inch rise may be considered normal in construction buildings where stairs are mostly used by the ill or elderly where they have to climb without using the full amount of energy. That will make it easier to access the riser. It is also important that the tread is wide enough.

Calculation of Riser and Treads of Staircase

There must be equality between every tread and riser. It is better to adjust with a calculator than to adjust one or two stair dimensions. You calculate the rise and treads of stairs by measuring the distance between the landing, where the bottom step rests, and the upper finished floor.

A total rise calculated by dividing it by the desired riser height. Round up or down if the result is a fraction. The height of the riser is determined by dividing the total rise by that number. A dimension to determine first before planning any stair is the rise and tread of the steps and their number.

The following points need to be considered before learning about rise and thread fix:
Two-floor clear distance (A) is 3.20 meters.
Distance between first and last riser on one flight (B) = 1.80m.

Staircase Riser Calculation

Decide the size of the riser first,
The riser size is 7 inch & range is 6-8 inch.
Risers = Clear Distance between Two Floors (A) / Risers Size
= 10foot 6 inches= 126 inches/ 7
= 18 nos.
It's 9 for the first flight and 9 for the second flight.

Staircase Tread Calculation

The next step is to calculate the tread size. Obviously, there is a difference in treads between a single flight and several rises for any stair. Depending on the type of stair, this dimension can be changed.

Formula for Riser Tread
Number of threads per flight = No. of risers per flight - 1
= 9 – 1
= 8 nos.
Thus, Tread Size = Total Stair Width / No. of Threads
= 6 foot = 72 inches/ 8
Tread size = 9 inch

Precautions: When calculating the design of staircases, here are some things to keep in mind:

• All parallel steps in a building should have the same tread and riser sizes on each floor.
• Any stair or step should have a minimum of 2 m of vertical space.
• For general safety reasons, a flight should usually not have more than 12 risers.
• 850 mm is the minimum width for the staircase. There may be three standard widths for stairs: 1.1 m, 1.6 m, and 1.9 m.
• Buildings used by the public, such as malls, cinemas, and shopping centers, may require wider stairways.

To get more clear ideas, go through the following exclusive construction video tutorial.

Lecturer: Civil Engineering Forum

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