Stairs by floor height · 2.55 m
Stairs for a 2.55 m floor-to-floor height
2.55 m (255 cm) from floor to floor takes 15 risers of 17 cm and 14 treads 29 cm deep: a pitch of 30°, and two risers and a going make 63 cm, an easy stride. A straight flight is 4.06 m long and needs an opening of 3.75 m in the floor above.
How it’s worked out
The fewest risers that keep each at most 18 cm (7″) high, all the same: 2.55 m ÷ 15 = 17 cm. The going follows the stair builders’ rule that two risers and a going make a stride of about 63 cm (25″). There is one tread fewer than risers: the last riser goes up to the upper floor itself.
If 2.55 m is your ceiling height, the stair is taller: add the floor above it, usually 25–35 cm — see stairs for 2.85 m.
More or fewer steps
Fewer risers make a shorter, steeper stair; more make a longer, easier one.
| Risers | Each riser | Going | Pitch | Run of a straight flight | How it walks |
|---|---|---|---|---|---|
| 13 | 19.6 cm | 25 cm | 38° | 3.00 m | steeper, fewer steps |
| 14 | 18.2 cm | 27 cm | 34° | 3.51 m | comfortable |
| 15 | 17 cm | 29 cm | 30° | 4.06 m | comfortable (drawn here) |
| 16 | 15.9 cm | 31 cm | 27° | 4.65 m | comfortable |
Limits differ by country: England’s Approved Document K allows a rise up to 220 mm and a pitch up to 42° in a home, Germany’s DIN 18065 up to 200 mm, and both ask for 2.0 m of headroom. Check the code that applies to yours.
This stair in each layout
Each drawn for 2.55 m: the flights 1.00 m wide, the spiral 1.60 m across, the square one in a 1.80 m stairwell. The size is over the treads. Pick one for its plan, its sizes and its parts.
Change anything
A different width, a turn the other way, closed risers, a steel frame: open the stair in uCAD and set it in the panel, or tell the AI what the stair has to fit into.
Other heights
Other heights: 2.50 m · 2.60 m · all heights
Measured between finished floors. A few centimetres change the riser, not the count, until a riser passes 18 cm.