By Huu Khanh Nguyen · Updated October 29, 2026 · stair, flight
A steep open-riser stair for access where there is no room for a standard flight, bar treads carried between two straight stringers.
| Name | Default | Unit |
|---|---|---|
| Number of risers (the flight has risers - 1 treads) | 10 | |
| Riser height, vertical distance between two successive treads | 228.6 | mm |
| Going, horizontal distance between the noses of two successive treads (y) | 106.6 | mm |
| Width of the flight over the stringers (x) | 674 | mm |
| Tread depth, front to rear (y) | 152 | mm |
| Tread thickness (z) | 41 | mm |
| Stringer section depth normal to the slope | 180 | mm |
| Stringer section thickness across the flight (x) | 32 | mm |
| Finish of the stringers and treads | white | |
| Slope of the flight from the horizontal, degrees (readout) | Math.atan(rise / going) * 180 / Math.PI | ° |
| Width (x) | width | mm |
| Depth of the box (y) | ((risers - 2) * going + treadDepth) - Math.min(0, ((treadDepth / 2) - ((rise - treadThickness / 2) + (stringerDepth * Math.sqrt(1 + (rise / going) * (rise / going))) / 2) / (rise / going))) | mm |
| Height of the box (z) | Math.max((risers - 1) * rise, ((rise / going) * (((risers - 2) * going + treadDepth) - (treadDepth / 2)) + (rise - treadThickness / 2) + (stringerDepth * Math.sqrt(1 + (rise / going) * (rise / going))) / 2)) | mm |