Tamal

Civil Engineer

Calculation of stair, the rise and tread calculation for standard stair is not so difficult to find out, but the concept of this stair calculation has some effort to give.

Actually, I have been worked for 4 years as a site Engineer, so I often see the drawing has a similar way of calculations and the calculations are very easy, But the fact is the stair designing is very much time consuming, but here I give you some easy formulae, in which you are able to find out the best and the easiest way to calculate and draw a stair drawing very easily.

when you start a building you always remember two things on your mind

1) The positions the stair minimum requirement is 2-meter width for the upward and downward stair.

2) The stair always starts from tie beam level.

In my next blog, I told you about the Tie Beam.

In AutoCAD when I start the drawing for my house, Firstly I Found lots of difficulties, But rather than that I prefer to discuss here the Stair designing, So when I came to the stair part I have lots of questions in my mind, how to start a drawing for floor as well as stair, because at that time I am not a Professional AutoCAD Designer, but now I am used too.

So when you start first of all the space in which you need to add the stair should have a minimum gap of 2000 mm.

Because stair width is about 900/1000 mm for residential, it is standard for maximum houses in India, but when you go to Delhi and other northern regions, you might have seen the stair width is about 600/800mm.

So the Question is how I add a stair with proper calculations, So here are the answers you need to follow.

1)Stair has a standard formula, for that, we need to know the floor height.

2)When we are going to add a stair we need to know the slope height.Slope height is the main calculation part of the stair.

So slope calculation is very easy actually.

Lots of formulae are there when you go to other blogs you might have found the IRC for stair design

You should check with your self that the stair you choose it is comfortable for every one or not.

Some of the formulas I want to share with you.

For Residencial building, the maximum riser height 7.75 inch and the riser is about 10 inch, so in practice, we refer a riser height is about 6 inch and the tread is around 8.5 inches, so this will be comfortable for all.

Let's focus on the Formulae we used in

rise r ≤ 7 3/4″

run R ≥ 10″

r+R = 17 3/4″ (good)

2r+R = 25 1/2″ (within range)

→ stair will be comfortable

run R ≥ 10″

r+R = 17 3/4″ (good)

2r+R = 25 1/2″ (within range)

→ stair will be comfortable

This is one type of formulae here you are practically searching or calculate on this with take several heights of riser and tread as well and put it on this given formula, you will realize that the actual standard slope and which stair is comfortable or not, but remember one thing is the standard range will be 25 inch

3)Here are another Formulae in which you could find the target slope for the stair.When you start the Drawing in AutoCAD drawing for a building plan, then I recommended this rule for target slope for stair calculation.

in mm

here you can see the maximum riser and tread dimensions for the stair.

The calculation 2xRiser + 1X Depth

Here you can see the actual range you have and the target you achieved right now.

So these two rules are very important for construct the staircase.

4)Nowadays For comfortable staircase design what we do, take a floor hight take a half height of the floor and take a slope at the distance of as same as the floor height, so you have an upward stair at the distance of the floor.

Example :

take a floor height of a building is 3000 mm,

Half of the height is 1500 mm now put a slope at distance of floor height 3000 mm and the actual riser total height will be 1500 with that taken slope.

then copy the same stair towards the 1st floor. and you can notice the same tread and riser you have got for stair design, so this is the thumb rule for stair in a residential building.

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