When a stair connects to a multilayer floor slab, the structural Stair Slab should connect to the structural/core component of the floor slab.
Currently, there seems to be no way to define this connection independently. The Stair Slab termination is generated according to the stair elevation/geometry, without taking into account the structural component of the adjacent multilayer slab.
Changing the stair Elevation can be used as a workaround to visually align the Stair Slab with the structural floor slab, but this moves the entire stair, including the steps and finishes, so it is not a proper solution.
The stair structure should be able to extend/trim automatically to the structural component of the adjacent slab, while the Tread Slab and other finish layers remain at their correct elevations.
This is particularly important with multilayer slabs, where the top surface of the floor and the top surface of the structural slab are at different elevations.
Thanks for the reply, @ng5_Alex, but the problem is a bit more complex. My example is simplified just to highlight a real issue.
If you want to model the floor build-up separately, so that the quantities are also correctly separated, the structural slab has to be lowered by the thickness of the screed/floor layers. As soon as I do that, the stair connection problem becomes apparent.
If I use Bottom Slab Thickness — which, by the way, I think should be available directly in the stair settings from the beginning — the connection improves, but it still doesn’t produce the correct result.
If I move the structural slab back to +/-0.00, the stair connection works correctly. But then the structural slab and the finished floor level are treated as the same elevation, which is not the actual floor build-up.
So the issue is not simply the Bottom Slab Thickness. The stair slab needs a proper connection rule to the structural/Core layer of the floor slab.
Oh, so now its not multi slab, its separately to get take off quantities, ok…anyway
as in real construction, the first step is always taller to accommodate finish floor layers.
No need to move any slab, you can do this with Bottom Slab Thickness. Provided your new condition, if the finish floor slabs are separated from the structural, you need 2 add interference between the structural slab and the stair and then the stair and the floor finish.
Similarly to this thread not reporting a bug, the youtrack link you provided seems to me totally irrelevant to this discussion.
The structural slab and the floor build-up are different construction elements. They have different materials, quantities, elevations and, more importantly, different intersection requirements.
For example, walls may need to reach the structural slab, while the floor build-up stops at the walls. The stair structural slab also needs to connect to the structural slab, while the finished floor remains at the floor level.
This is precisely why I separated them: the section also needs to be represented correctly, which is not possible with a multilayer slab in the current implementation.
P.S. You’re right about the YouTrack link. That was my mistake — it was intended for a different discussion about Worksessions and is unrelated to this issue.
The stair slab bottom and top thicknesses are available in the stair insert dialog.
Setting a stair slab thickness = to the finish slab layer will make the stair reach the structural slab layer, as @ng5_Alex suggested.
I can see that when the stair slab “touches” the structural slab (when that layer it’s an individual slab), the intersection is not cleaned after running the vaAddInterferences command between the slab and the stair. We will revise this.
