Hello everyone,
I'm trying to model a stair where the first four treads are "compensated" (meaning the nosing is adjusted to fit a specific landing or winder condition), and from the 5th tread onwards, they are standard, equal treads, like the floor plan below.
I'm working in Archicad 28 and using the Stair Tool. I can successfully create the compensated treads and risers by dragging the nodes in the floor plan, but the problem is that the stair's underlying structure remains unchanged, which causes issues for the rest of the flight.
Is the best approach to model this as two separate stair elements? Or is there a way to define a "transition node" within a single stair object where the tread compensation stops and the structure recalculates for standard treads?
Does anyone has any experience in this?
Thanks in advance.
Hector
Operating system used: Windows
1 ACCEPTED SOLUTION
Accepted Solutions
Hello again everyone, especially @Barry Kelly ,
I'm writing to close this thread with the solution and to thank everyone—especially Barry—for the crucial insight that solved my problem.
It was possible to model the stair correctly from a single center point, once I understood how to define it.
In my earlier attempts, I was adjusting the stair's boundary lines and nodes based on my 2D plan, but I was doing so without correctly setting the stair’s actual center of rotation. As a result, the geometry was inconsistent, and the 3D structure would not update properly—it remained as if the stair was still purely tangent, even when the treads looked right in plan.
Barry’s last comment made me realize I wasn't defining the problem correctly for the tool. I went back and properly set the stair’s center point in the stair settings—aligning it with the real, physical center of the existing curved flight. Once I did that:
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The treads automatically compensated correctly, I have to aproximate some measures.
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The thread finish updated perfectly.
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The transition from the curved start to the straight run was cleaner.
The key takeaway for others:
If you’re modeling an existing curved or partially curved stair and the 3D structure won’t follow your 2D adjustments, double-check the stair’s center point definition. The tool needs that reference to calculate the tread compensation and the structural soffit correctly. The boundary line edits alone aren’t enough—they have to work in concert with a properly placed center.
Thanks to @Yves for the video: https://youtu.be/8I4PLZBbuUc to correct the curve stair.
I’ve attached a screenshot of the final, correct stair, both in plan and 3D. The structure now matches the existing conditions perfectly.
Thank you again to everyone who chimed in. Sometimes the answer isn’t in fighting the tool, but in stepping back and making sure you’re giving it the right foundational information.
hopefully this helps someone else avoid the same head-scratching.
Best regards,
Hector
Hello All,
I'm following up on a previous tips and video about creating a stair with compensated treads. With your help, I've managed to compensate the treads and risers successfully, and the 2D symbol and the stair's top surface.
However, The structural component of the stair I cannot modify it. It remains shaped as if the stair were still tangent, creating a conflict between the tread-riser and structure.
I see that the base line is still tangent
but when I make it a straight line it unmade the steps 😓
I'm starting to think the issue might be that my initial tangent curve is too steep or extreme for the Stair Tool to cleanly generate a transition to the straight run.
Has anyone encountered this and found a solution? is there a practical limit to how much you can compensate a tread before the structure fails to follow?
Thank you.
Hector
Hi Barry,
I already did that and the structure boundaries are straight but the steps on the structure are not.
As you can see on the screenshoot below:
Regards,
Hector
Try pulling the front node of the reference line to the side so the curve is tangential to the vertical line above.
Barry.
Hi Barry,
Indeed, I can change the the line reference to make it tangencial to the vertical line:
but this way i cannot have control where the steps start. Now the orientation is good but the I have 2 extra steps:
and adding a extra part of the estructure.
Regards,
Hector
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