1. Basic geometric parameters
Radius and step count
The radius (or diameter) of an arc-shaped staircase directly affects the number of steps and the slope. A smaller radius means a steeper staircase and more steps; a larger radius means a gentler slope.
Minimum radius: Usually no less than 1 meter (for household use), otherwise the steps will be too narrow and affect safety.
Number of steps: It is recommended to be at least 12 or more, to avoid too close steps which would make the slope too steep (generally the slope is between 20° and 40°).
Step dimensions
Step width: The outer side (straight length) should typically be ≥ 26cm, and the inner side (arc length) should be ≥ 20cm to ensure comfortable walking.
Step height: It is recommended to be 15-18cm, which is in line with ergonomics.
Step depth: The outer side depth should be ≥ 28cm (in accordance with building regulations), and the inner side can be slightly smaller.
2. Required space dimensions
Main space of the staircase
Diameter/Width: If the diameter of the staircase is 2 meters, at least 3m × 3m of space (including handrails and decorations) should be reserved.
Rotating staircase: For a rotating staircase with a diameter of 1.2 to 1.5 meters, approximately 2.5m × 2.5m of area should be reserved.
Straight section: At both ends of the arc-shaped staircase, a straight running section needs to be reserved, with a length usually ≥ 1.2 meters (to facilitate turning when going up or down the stairs).
Reserved space around
Single side: At least 60-80cm should be reserved (for people to pass through or place furniture).
Double side: It should be ≥ 1 meter (if designed against the wall, the outer side needs to leave space for handrails and passage).
Top space: The floor height should be ≥ 2.4 meters to avoid a sense of oppression.
