This is a problem, especially when the stair has winders.
Flat landings aren't a problem.
There must be a few post about this - here is one i can find.
https://archicad-talk.graphisoft.com/viewtopic.php?f=20&t=66176
You can 'Split' the structure of the stair and it gives you a little more control as you can adjust the base depth.
But it will still be curvy.
The best I can come up with is to model the flights and winders as separate stairs - at least then they will be flat underneath.
Create one full stair as you have done to get the riser height, ALT-click it to get the settings and then create each segment using the 'flexible' method so they are not linked to storey heights.
Then adjust the height of each segment in 3D so it flows as one stair.
You will have to adjust the numbering, walking line and break line in the plan.
Barry.
One of the forum moderators.
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