For Priority Based Intersections involving any Roof, Shell or Morph element, the intersection is not created automatically just because the elements intersect in 3D.
The Connect\Merge Elements command (from the context menu) needs to be used to explicitly establish the connection:
https://www.youtube.com/watch?v=V_8CJT8TWik&list=PLnXY6vLUwlWWa_BD5mX2l2YujV_CMtXFO&index=7
However, this may only be part of the resolution of this particular case. Examining this situation brought to my attention an aspect of how Priority Based Conections work which I am not sure is mentioned anywhere in the New Features Clips or in Help. So I share it with you here.
It concerns how ArchiCAD calculates which skin is stronger.
The reason the Wall structure does not cut skins of the Roof is because the Roof's skins are stronger, they have a higher intersection priority number.
But the trick is here: let us say you have a Wall skin with an Intersection Priority Number of 600. Let us say it intersects with a Roof that has 3 skins with Intersection Priority Numbers 700, 500 and 800. One would expect that the 700 and 800 skins of the Roof to cut the 600 skin of the Wall, while the 600 skin of the Wall to cut the 500 skin of the Roof.
What I found is that this is not the case: since the 500 skin of the Roof is situated between two skins that are stronger than the 600 Wall skin, therefore this weaker skin between those stronger skins will also cut the 600 Wall skin, despite that it is a stronger skin.
This gives a rule for us: To avoid such situations, as we progress from the core of a structure (or from the skin of the structure with the highest Intersection Priority Number) outward the Intersection Priority Numbers of skins should be progressively less and less.
So this would be good:
300
400
500
800 (Core)
500
400
But this could cause unexpected results beause of the above stated reason:
600
400
500
800 (Core)
500
400
Please let me know if this resolves this issue.
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