Curved Closed Stringer Flight
By Huu Khanh Nguyen · Updated October 28, 2026 · stair, curved-flight
A curved stair flight with an inner and an outer curved string that enclose the treads and, optionally, the riser boards.
Parameters
| Name | Default | Unit |
|---|---|---|
| Number of risers (the flight has risers - 1 treads) | 17 | |
| Riser height | 175 | mm |
| Inner radius of the flight in plan (the well) | 255 | mm |
| Radial width of the flight | 945 | mm |
| Total turn of the flight in plan | 360 | ° |
| Direction of climb seen from above | left | |
| Tread thickness (z) | 40 | mm |
| Riser boards | true | |
| Riser board thickness | 19 | mm |
| String thickness across the width (radial) | 30 | mm |
| Housing depth of the treads in the string (radial) | 12 | mm |
| String margin above the tread top and below the tread underside (plumb) | 50 | mm |
| Finish of strings and risers | white | |
| Turn of one step (readout) | angle / (risers - 1) | ° |
| Walkline distance from the inner edge (readout) | Math.min(width / 2, 500) | mm |
| Going on the walkline (readout) | (innerRadius + Math.min(width / 2, 500)) * stepAngle * Math.PI / 180 | mm |
| Height | risers * rise | mm |