|Carpentry for Vocational Schools - A Teachers Handbook|
You are advised to make the calculation for the stairs on the building site or with a proper drawing in a scale of 1 : 10 or 1 : 20 in order to make sure the stairs will fit correctly.
The HEIGHT of the riser is calculated by dividing the floor to floor height into a suitable number of risers each being approximately 175 mm.
The GOING is calculated by dividing the total going into a suitable number of treads each going being approximately 250 mm.
Total Going = 3250 : 13 treads = 250 mm
Total Rise = 2450 : 14 risers = 175 mm riser
When more space for the going is available, the go can be made up to 300 mm.