Stairs by floor height · 3.05 m
Stairs for a 3.05 m floor-to-floor height
3.05 m (305 cm) from floor to floor takes 17 risers of 17.9 cm and 16 treads 27 cm deep: a pitch of 34°, and two risers and a going make 62.9 cm, an easy stride. A straight flight is 4.32 m long and needs an opening of 3.31 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: 3.05 m ÷ 17 = 17.9 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 3.05 m is your ceiling height, the stair is taller: add the floor above it, usually 25–35 cm — see stairs for 3.35 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 |
|---|---|---|---|---|---|
| 15 | 20.3 cm | 25 cm | 39° | 3.50 m | steep: over 20 cm, more than many codes allow |
| 16 | 19.1 cm | 25 cm | 37° | 3.75 m | steeper, fewer steps |
| 17 | 17.9 cm | 27 cm | 34° | 4.32 m | comfortable (drawn here) |
| 18 | 16.9 cm | 29 cm | 30° | 4.93 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 3.05 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: 3.00 m · 3.10 m · all heights
Measured between finished floors. A few centimetres change the riser, not the count, until a riser passes 18 cm.