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Straight stair calculator

This live spreadsheet is based on the Building Regulations and works on the assumption that you have a fixed floor to floor dimension (total rise) but you may want to vary the number of steps and their size and the slope. You can input the number of risers you want and their goings and the spreadsheet then checks whether they conform to the Building Regulations. Enter your guestimate values into the green boxes and then the red text comments indicate whether the necessary conditions are met. Other values such as riser height and pitch get calculated. If the conditions are not met you need to try different goings and risers.

Notes:

  1. Stairs are limited to 36 consecutive risers in a flight unless there is a change in direction. See para 1.14 in the Approved documents.
  2. Risers are not allowed to exceed 220mm
  3. It is important to work to 0.1 of a mm.  (or better) because cumulative error on many steps can become significant
  4. The greater the going the shallower the pitch of the stairs. You can’t have a combination of the maximum risers (220) with the minimum goings (also 220). It makes it too steep (over 42 deg). Longer goings make for shallower but longer stairs.
  5. If this result does not fall within 550-700 try adjusting the risers (via the number of risers) and the goings. The formula comes from the Building Regulations.
  6. if this is above 42 degrees then try increasing the going (or increasing the number of risers to make them smaller)
  7. The total length is the horizontal distance from the nosing on the top landing to the position on the lower landing directly below the lowest nosing.

See more detail at Staircase Design