Stairs are something most of us use every day without giving much thought to.
But you may be wondering – what exactly makes up a single flight of stairs? How did we come to that number?
A classic flight of stairs consists of 12 steps. However, the number of steps in a flight depends on the ceiling height, as a ten-foot ceiling requires additional steps compared to a standard eight-foot one.
Ceiling and wall heights matter when determining the number of steps that a single flight of stairs might have.
Read on for informational insights about flights of stairs, their maximum and minimum steps, necessary measurements, and more to help answer all your questions.
What Is Considered a Flight of Stairs?
Typically, a flight of stairs refers to a continuous set of stairs. These stairs do not have a landing in the middle that separates the single set of stairs.
Instead, the flight of stairs is built to be equal in size and measurements that run uniformly without interruptions.
In addition, it is also important to note that stairs with landings are not called a “flight of stairs.” Instead, flights of stairs mainly refer to an unbroken arrangement of steps with no landing but rather a starting floor and an ending floor.
Requirement of Steps in a Flight of Stairs
Flights of stairs can be straight, running, spiral, or even curved. No particular number of steps is required for a flight of stairs.
The only requirement is that they do not have any landing or stop.
However, flights of stairs are generally characterized by 12 to 15 steps to make a standard and comfortable tread way for people of all ages.
Origin of the Phrase “Flight of Stairs”
An old French saying says “flying upstairs” is “traveling back in time.” Moreover, the word “flight” means the flow of a moving body without interruption.
This is how the phrases and words came to mix to form the meaning of “flight of stairs.”
Many people tend to confuse steps with “flight of stairs.” But they are not quite the same. More generally, steps are referred to as stairs set up or built outdoors, whereas a flight of stairs refers to an arrangement of stairs constructed indoors.
How Many Steps Are in a Flight of Stairs?
On average, most flights of stairs consist of 12 to 13 steps according to the building, along with the height of the stairs and the purpose the stairs will be used for.
For example, it is commonly seen that 10 foot ceilings require about 17 steps, 9 foot ceilings need about 16 steps, and 8 foot ceilings need 14 steps.
Calculating the Number of Steps
Many steps and methods can be taken to calculate the number of stairs in a flight.
However, perhaps the easiest way to calculate the answer is by considering the overall ceiling height (which includes the length and width of wood joists) and the diameter of the subfloors (flat structures installed around the joist beams).
Here are some individual calculations as per the ceiling heights below for better understanding.
Calculating 8 Foot Ceilings Steps
Let us consider a building, house, or structure with 8 foot ceilings and 10-inch broad stair joists supporting the floor.
- 10-inch joists make up a diameter of 9 ¼ inches. In addition, there are ¾ inches of subfloors that are built above the beams.
- The total height from the starting floor to the ending of the flight of stairs can be 8 feet and 10 inches. So, go ahead and convert all of it into inches; the answer should be 106 inches.
- Afterward, use the IRC standard stair rise measurement (7 ¾ inches) and have 106 inches divided by it to get approximately 14. This means 14 steps are ideally required for 8 foot ceilings and 10-inch flight of stairs.
- Divide 106″ by 14 to find the rise per each step, and you get 7.6, or about 7 9/16″ rise per step.
Calculating 9 Foot Ceiling Steps
For people living in places with 9 foot ceilings, the total height for the flight of stairs should be around 118 inches by using the same method as above. Remember to consider the measurements of joists and subfloors.
- Start by dividing 118 inches by the IRC standard of 7 ¾ rise measurement, and you will get approximately 15.
Always taking approximate values might be theoretically alright but can impose structural issues practically. For example, if you take the approximate value of 15 rather than 15.2 (the actual answer), you might end up with an extra final step in the flight, which will measure 4 inches.
Make sure you take accurate measures when working in the actual field of stair building.
In short, houses or places with 9 foot ceilings will ideally require 16 steps to be built. You can get 118 inches divided by 16 afterward, which will give you about 7.4″, and this is closer to the IRC standard.
Thereby, you will be able to have 16 steps in a flight, with each step measuring about 7.5 inches.
Calculating 10 Foot Ceiling Steps
Again, consider the methods and dimensions used in the previous examples to find the number of ideal steps.
- For 10 foot ceilings, consider the 10-inch diameter of joists and ¾ inches of subfloors. As a result, you will get 130 inches for the total rise height.
- Divide 130 inches by the IRC standard of 7 ¾ inches, which will give you an approximate value of 17, so 17 steps it is!
- Then, if you wish to find the rise per step, divide 130 inches by 17, and you will get about 7.7 inches of height for each step of flight.
Minimum Number of Steps in a Flight of Stairs
In terms of the professional building principles, there are no exact numbers we have to show how many stairs a flight should ideally have.
However, the building code principle states that the highest height of a riser should be about 7.7 inches, which is commonly considered the standard for a secure and ideal flight of stairs. Therefore, this number can be used to find the minimum number of steps that a flight of stairs should have.
According to IRC, the limit for vertical risers lying between landings or each floor should be within 12 feet. If we put our brains to work, we can figure the minimum number of steps for this height.
- Let’s start with converting 12 feet into inches, which is 144 inches. Divide 144 inches by 7¾ (approx. IRC standard), and you will get 18.5.
This brings us to conclude that a 12 foot vertical riser will require 19 steps per flight. A landing is needed at the end of this 19-stair flight. You can use this same method in the case of other heights of vertical risers to determine the minimum steps required.
Maximum Number of Steps in a Flight of Stairs
Unlike the minimum number of steps that a flight of stairs should ideally have, a certain number of steps are deemed maximum for a flight of stairs.
The IBC has stated that the minimum height is 4 inches, and a shorter riser will only impose safety hazards. Thus, the ideal riser height is between 4 inches to 7 ¾ inches.
To find out the maximum ideal steps a flight of stairs should have, let us consider a vertical riser of 12 feet again.
- Similarly, convert the 12 feet riser height into inches, and you shall then get 144 inches.
- Then, divide 144 inches by 4, and you will get 36.
So, conclusively, 36 steps are the maximum number of steps that an ideal flight of stairs should have.
Conclusion to How Many Stairs Are in a Flight of Stairs
It depends on the height of the ceilings and how high the rise of the stairs are. You can calculate how many stairs should be in a flight, but it generally varies between 12 to 15 stairs with normal ceiling heights.
The only thing that doesn’t qualify as a flight of stairs is if they have a landing breaking up the stairs themselves.