This chart gives preferred rise/go dimensions see section coloured yellow for any given rake of staircase or ladder and is based on our recommended formula: Twice the rise plus the go = not less than 570mm nor more than 640mm (550 to 700).

‘Go’ is the term used for the horizontal dimension of a stair or tread. ‘Rise’ is the vertical dimension. ‘Overlap’ is the amount the nosing of one tread overlaps the one below (minimum16mm).

Example: A single flight stair has a rise of 2600mm and has to comply with a minimum tread ‘go’ of 250mm and a maximum rise of 190mm. From the chart below we see with a ‘go’ of 250mm an acceptable rise will be about 185mm. This will give 14 equal rises. The stair will thus have an angle of rake pitch of 36º 36’ and will fall within the limits required for this type of stair. Also the aggregate of twice the rise plus the go equals 620mm, close to the optimum recommended in BS 5395 Part 1.