By Huu Khanh Nguyen · Updated October 28, 2026 · stair, curved-flight
A cast concrete flight of stairs that turns on an arc, one solid body whose steps sit on a sloping curved slab.
| Name | Default | Unit |
|---|---|---|
| Number of risers in the flight (the flight has risers - 1 treads, the upper level is the landing) | 18 | |
| Riser height | 150 | mm |
| Radius of the inner edge of the flight in plan (the well) | 1000 | mm |
| Radial width of the flight | 1500 | mm |
| Total turn of the flight in plan | 180 | ° |
| Direction of climb seen from above | left | |
| Waist thickness, the minimum measured perpendicular to the slope (at the inner edge) to the inner corner of riser and tread | 150 | mm |
| Bearing on the upper level, along the mean radius from the last riser to the end face | 110 | mm |
| Finish | white | |
| Plan angle of one step | angle / (risers - 1) | ° |
| Going on the walking line | (innerRadius + Math.min(width / 2, 500)) * stepAngle * (Math.PI / 180) | mm |
| Tread length at the inner edge | innerRadius * stepAngle * (Math.PI / 180) | mm |
| Vertical drop of the soffit below the line through the riser base corners | waist * Math.sqrt(1 + (rise / (stepAngle * (Math.PI / 180) * innerRadius)) ** 2) | mm |
| Height of the upper level above the lower floor (z) | risers * rise | mm |