Intersection priority doesn't work properly

[Isaac Newton]

Good time of the day gentlemen

I have the finish floor and partition walls with various intersection priorities set to their materials. They don't work as expected however. Bellow is the section of the intersection:

The wall should go through the insulation on the floor, however it doesn't.

It should be noticed however, that that's a new project, created in ArchiCAD 26, and the legacy intersections are turned off in it

Can you please help me with that?

[Lee Hankins]

Could it be because the intersection priority is '0', have you tried changing it to '1'. I am not sure if '0' is accepted or creates some form of override that prevents any sort of intersection from occurring.

I've been using AC for 24 years and still can't get my head around building material proprieties since it was introduced in AC17.

[Isaac Newton]

Unfortunately that's not the case either. I've set it to zero as a test, you see. Before that it was 220 or something, and still it didn't work.

[Barry Kelly]

How far does the wall extend down?

Try a wall that goes to the bottom of the slab and another that starts below the slab.

You might see a difference in how they trim.

Barry.

[Isaac Newton]

Alas, that doesn't make any difference either. The wall cuts the very same material below, however:

I'm beginning to think that the problem might be with something else than the priority. You see, the insulation layer below the slab is created as a single layer slab, while, the insulation above the slab (the one that doesn't work), is a part of the multilayer slab of the floor finish. Perhaps this is the case then? But still I don't understand what's wrong with that. All the skins of both structures (the wall and the finish floor) are set as "other".

In a general way all this issue is a part of a larger issue that occured when I tried to calculate the areas of interior partion walls. If you have time and if you don't mind perhaps you could take a look at this question, I've made a bit earlier: How to calculate areas of the partition walls for ... - Graphisoft Community

The reason why I decided to pay attention to this intersection is discussed in the comments. But unfortunately, I haven't resolved it yet as well

[Isaac Newton · Accepted solution]

My appologies. After a fair bit of experimenting I finally found out what was wrong with it. The thing is that in this multilayer slab that represnts the finish floor, I have two layers of water and vapour proofing with zero thickness. The heat and sound insulation is sanwiched between those two layers. The material of that proffing had a higher priority than the material of the wall. Therefore those two layers together with insulation incased inside of them (and having the smaller priority) were cutting through the wall:

That's how it was:

That's how it became: