While planning a staircase, it’s important to understand how would you calculate the number of steps within the angle or the slope of the staircase slant.
In order to calculate the total number of stairs required for a particular height, we need to first know the total height of the room.
For example say the total height of the room is 12 ft, we first need to subtract a reasonable head space height from the total height to get the height of the staircase. A reasonable height to subtract would be 7ft, therefore:-
12 ft − 7 ft = 5 ft = Total Height of the Staircase Flight
Every staircase, has RISERS and Treads. Risers are the vertical pieces that make up each stair while treads are the horizontal pieces that make of an individual stairNow, first of all we need to understand and define what a stair RISE and TREAD is.
The Rise of the stair is the height of an individual stair or it may also be called as the height of an individual riser. An average height of one stair or the rise can be anywhere between 4-8 inches, but a comfortable height would be 6-7 inches.
The Tread of the stair is the depth of the individual stair. It’s normally the space where a foot is placed over. A comfortable tread would be 9-12 inches.
What is a Landing? :- The flat distance at the bottom of the stair case before the first riser and the top of the staircase after the last riser are called landings
In the present example, the height of the stair is 5 ft which means the total rise of all the number of stairs combined would be equal to 5ft. Therefore, Total Rise = 5 ft
In order to know the total tread, we need to decide the point from where the first riser/ first stair would start. The total tread would then be horizontal distance between the bottom of the first stair to the start of the top landing [where the top of the last stair would meet the top landing].
It maybe useful to know that a good comfortable staircase is aligned at an angle of 32 degree to 42 degree. Such an angle is normally known as pitch. 42 degrees should generally be the maximum pitch of the staircase. [Pitch is beyond the title of this article]
Let’s say the total tread in this example is 9 ft
NOTE:- ALWAYS HIRE A PROFESSIONAL FOR ANY JOBS AS IT MAY BE DANGEROUS FOR A LAYMAN AND INEXPERIENCED PERSON.
At a comfortable angle and looking at where we need the steps to start, we decided the total tread would be 9 ft.
Now, If we decide the height of each rise to be 6 inches, then
Total number of Rise = Total Rise ÷ Rise = 5 foot ÷ 6 inch = 60 inch ÷ 6 inch = 10
Total number of Tread = Total Rise - 1 = 10 - 1 = 9
The total number of treads is always one less than the number of risers because the landing is never counted under tread. The following image with 4 risers and 3 treads may help to clear it:-
We have calculated the total number of risers and treads and we know the height of an individual rise to be 6 inch but we still don’t know the depth of an individual stair. To calculate the depth of an individual stair or the Tread :-
Tread = Total Tread ÷ Total number of Treads = 9 ft ÷ 9 Treads = 108 inches ÷ 9 = 12 inches
Therefore, the Tread or the depth of each stair would be around 12 inches.
A normal comfortable staircase should have a width of 300 millimetre for ease of access.
Note that the tread is also known as the RUN or the GOING.
A general formula for calculating tread and riser dimensions is:-
2x Rise + GOING = 600mm [550 to 700mm is normally acceptable]
So if one knows either the Rise or the Tread/ Going then, one can calculate the other variable easily.