Designing a stair

• To set out a stair  , it is necessary to select a suitable rise and adjust it , if necessary . 
• Then select a suitable going . 
• Before standard were set for the rise and going of steps , it was practice to determin the convenience of steps from the simple formula :
• 2 Rises + 1 Going = bwteeen 550 and 700mm 
• It is important to note that in any one flight , there will be one more riser than treads . Since the last tread is in fact the landing . 

Example
The dimensions for the staircase are :

• Vetical rise = 2760 mm
• Staircase length = 3000 mm
• Preferred riser height = 190 mm 

Solution

1. Divide the vertcal rise by the riser height to find the number of risers = 2760 / 190 = 14.53 risers ( try 14 risers )
2. Find the exact riser height by dividing the vertical rise by the number of risers  = 2760 / 14 = 197.14 mm
3. FInd the going to suit the desired staircase length =3000 / 13 =231 mm
4. Use the formula 2 risers + 1 going to see if this design is comfortable = (197.14 x 2 ) + 231 = 625.28 mm ( it between 550 and 700mm )
5. Does the design come within the allowable limit 7 . 
6. It yes , use staircase with 14 risers , 231mm going and 197.14mm riser
7. It No , repeat from step 2 with 15 risers . It will still doesn't fit , increase the staircase length and repeat from steps 3 .