Stairs are an integral part of a house or any structure. When constructing a staircase, one must consider different factors, such as the building codes, apat from parameters and calculations related to staircase length, width, height, placement of doors, etc. A stair calculator is useful when calculating these parameters related to staircase construction. Here is a guide.
The number of items of a staircase depends on the type of staircase, the materials used, and the design.
However, there are some general items that are common to most staircases.
- Risers: The risers are the vertical pieces that separate the treads. The number of risers will depend on the height of the staircase and the desired rise height.
- Treads: The treads are the horizontal surfaces that you walk on. The number of treads will depend on the number of risers and the desired run length.
- Stringers: The stringers are the supports that the treads and risers are attached to. The number of stringers will depend on the length of the staircase and the type of stringer used.
- Balusters: The balusters are the vertical posts that support the handrail. The number of balusters will depend on the width of the staircase and the desired spacing between the balusters.
- Handrail: The handrail is a horizontal rail that you can hold onto for support. The length of the handrail will depend on the length of the staircase and the desired height of the handrail.
- Newel posts:Â The newel posts are the vertical posts at the ends of the staircase. The number of newel posts will depend on the design of the staircase.
In addition to these common items, there may be other items that are specific to the type of staircase or the materials used.
For example, a spiral staircase may have different components than a straight staircase. And a wooden staircase may have different components than a concrete staircase.
To calculate the number of items for a specific staircase, you will need to know the dimensions of the staircase and the desired specifications. You can then use the formulas for risers, treads, stringers, balusters, handrail, and newel posts to calculate the number of each item.
Here is an example of how to calculate the number of risers for a staircase:
- Assume the height of the staircase is 8 feet, or 96 inches.
- Assume the desired rise height is 7 inches.
- Therefore, the number of risers is 96 inches / 7 inches = 13 risers.
Once you have calculated the number of each item, you can then add up the total number to get the total number of items for the staircase.
What is a stair calculator?
A stair calculator is a digital tool used to calculate unit rise and run of stairs, stair elevation angle, stringer length, step height, tread depth and the number of steps required for a given run of stairs.
Stair calculator: How to calculate stairs?
Let us assume a floor-to-floor level of 600 mm for determining stairs. For example, according to the building regulations, the riser height allowed is 150 mm to 220 mm.
Minimum riser height = 150 mm
Number of steps = overall change in level (overall rise)/ minimum riser height = 600/150 = 4
Thus, we can construct four risers or steps in the staircase.
*The rise and run calculator of a staircase is applicable for a single flight of stairs. In the case of a landing, every flight must be considered separately.
Stair calculator: Flush mount vs standard mount
It is also essential to determine if the staircase will be installed on a standard mount or a flush mount. The last tread of stairs is one step lower than the floor level in a standard mount, while it will be at the same height as the floor level in a flush mount.
How to calculate the run?
The number of stairs equals the total rise divided by the rise. If the height of the first step is different, it must be accounted for when calculating stairs.
Now, the total run = run x number of stairs
For a standard mount, you must deduct one from the number of stairs.
Stair stringer calculator
Stringer length is calculated based on the Pythagoras Theorem.
i.e., stringer length² = total run² + stinger height²
The stringer height = total rise in case of the flush mount to total rise in a standard mount.
Stair angle calculator
The mathematical formula for calculating the stair angle is given below:
angle = arcsin (stringer height / stringer length)
Staircase terminology
Run or tread
It is a component of the staircase, on which a person steps when climbing stairs. The length of the run or a tread is calculated from the outer edge of a step, including the nosing, to the vertical surface called the rise. The length of the tread above the last riser is not included when calculating the total run of a staircase.
Nosing
Nosing refers to the protrusion at a tread’s edge projecting over the riser in the lower level. The nosing is counted when measuring the tread’s length. However, the total run cannot be calculated basis the sum of tread length when nosing is present as the overhang caused should be subtracted from the total run.
Rise or riser
Riser is the height of the step calculated from the top of a tread to the top of the subsequent tread. It excludes the thickness of the tread. The number of risers is calculated to determine the number of staircase steps.
Stair stringer
It is a structural component of a staircase that supports the treads and risers. Normally, there are three stringers in a staircase – one placed on either side of the staircase and one at the centre.
Staircase width
The width is calculated from one edge to another edge of each side of the tread, perpendicular to tread length. Handrails are excluded from the calculation. Usually, the width is the longer side in staircases.
Headroom
Headroom refers to the height calculated from the top of a tread to the ceiling. The headroom is essential as it allows people to get enough space to move comfortably through stairs.
Handrails
A handrail refers to the railing running up the staircase incline and it is designed to provide support to people to safely climb or descend the staircase.
Landing
The landing refers to the platform that connects two flights of stairs.
Stair calculator table
One can use the Stairs calculator to calculate unit rise and run of straight stairs.
- Unit rise is 0.192 m
- Unit run is 0.231 m (0.281 m incl. nosing projection)
- Elevation angle is 39.8 degrees
- Unit rise is 0.192 m
- Unit run is 0.231 m (0.281 m incl. nosing projection)
- Elevation angle is 39.8 degrees
How many steps will I need? As per the Indian National Building Code, the minimum width for a staircase in a residential structure must be 3 feet and 6 inches while the tread without nosing must have a minimum width of 10 inches and 10 ¼ inches if nosing is required.
For a 12-feet high ceiling or floor in a building, there is a requirement of 21 stairs or steps or riser, 20 number of tread and about 14 feet of stringer to go up.
How to use stair stringer calculator?
A stair stringer calculator is available online. Before using the calculator, make sure you have the following details:
- Total height of stairs required
- Local maximum riser height as per the building code
- Local minimum riser height as per the building code
- Local minimum tread depth (run)
- Local minimum tread overhang, the length from the face of the riser to the front edge of the nosing
- Local maximum tread overhang, the length from the face of the riser to the front edge of the nosing
To use the calculator, input details such as the size of run in metres/centimetres, total rise in metres/centimetres to get details on the number of steps, stringer length, angle, etc.