VisualARQ - What's the easiest way to merge slabs together into one?

I may have missed something and they might do this automatically? But let’s say I’m tracing a PDF and find it easier to draw multiple sections at once. Thereafter adjust the elevations of some sections. Is there a way to merge the slabs? So far I think I would just explode the slabs, booleanUnion them, and then somehow 'IFC them back into a slab (haven’t figured out the last part yet).

Please let me know if there is a better workflow.



Hi Keith, there is no command to merge slabs. We plan to add an option for that, but it will only work with slabs that are properly aligned, and one will take the properties of another (style, thickness, material, etc…)
As a workaround, you can run this simple GH definition:

  1. Reference the slabs to join with the Slab Param component.
  2. Bake the ending Slab component
  3. Delete the original slabs

Slab (5.6 KB)


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Do without Grasshopper:

  • explode the second slab twice
  • CTRL-SHIFT-select top surface of the exploded slab
  • DupBorder
  • select first vaSlab
  • vaSlabAdd (= Add Boundary in the toolbar), select the boundary curve you just created
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You can also run Silhouette and then CurveBoolean to get the curve.


Btw: the Silhoutte command creates ALL edges of an object (e.g. a box would result in 12 edges), so to get the outline you need, only select the top (or bottom) surface after exploding.

You can run silhouette without exploding the slab. Then I run the CurveBoolean command with Delete=All + AllRegions

Thanks everyone!
I’m fairly okay with adjusting the geometry. I just can’t turn it back to an IFC Slab type object. For what I’m actually planning to do with Rhino this doesn’t actually matter much however - Using the slab tool to draw slabs and then just exploding them, and doing some sort of union afterwards will work perfectly fine. I might revisit this when I’m at a higher skill level however.

Grasshopper is neat but I have no idea what the hell I’m doing :wink: .

Btw. Slabs can of course be edited by turning on their control points, but what’s missing is some kind of InsertPoint command (deleting points works). This would often be quicker than using vaSlabAdd.
Have wished for this already. Just mentioning it here again.


@eugen, @keithscadservices, @rheinason We have developed a command to join slabs that is included in the VisualARQ labs plug-in: Labs - VisualARQ

You need VisualARQ 2.13 to use it.

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