Missing materials in IFC when exporting from Archicad

[Norbert Pinter]

Hi!
We have just realized that the information of the building materials are not included for all of the composite elements when we export IFC from our model. Weirdly it happens even when we export the IFC with "All BIM Properties" and we select all "Archicad Data to Export" as well at the section Data Conversion for the IFC translator.
Somehow the whole Material section is missing for some of the objects when opening the IFC with a viewer (Solibri, BIMcollab). It happens only with composite structures and it is important for us to have this data in the IFC model. In other projects it happens as well, but quite randomly. For some of the composite walls for example it exports this data, but for some of them not. 
What do I need to change to have them exported correctly and for every single element/object? 

an example of correct data (Solibri)an example of missing data (Solibri)an example of missing data (BIMcollab)

[hybrid]

Try to open the IFC file that I attached to the answer. I have configured to export for Navisworks

[Norbert Pinter]

Tried it and it seems that the problem is the same.
In your file there are two walls with the data of the materials which are included and there are two without the information. Do you have any idea what is the reason for this and how can we avoid the problem?

[hybrid]

This I tried to give different classifiers and settings on the walls, if you want I can send you .pln format AC24., You can look there in more detail. I just warn you that I have a RUS version of AC and all the texts in Kirrilitsa

[Norbert Pinter]

That would be helpful!

[Norbert Pinter]

Could you send it in AC23?

[Johan Stinckens]

Goodmorning Norbert,

Could it be that the first wall in your example is a basic structure, and the second a composite?!

In the example @hybrid has provided, the two leftmost walls are basic structures, so the material is attached to the whole object. The two rightmost objects are composite structures for which the material is set to each of its skins.

Can you try and select just one of the components in your IFC viewer (for Solibri this is Shift-Click). The material for the skins should be there.

Are you trying to get Information Takeoff from Solibri and missing the content for the skins that belong to the composites?!

That is an issue I have at the moment. Will create a topic for that.

Good Luck.

[Norbert Pinter]

Good morning Johan,

In my example all of the walls are composites and having problems with them only. I have no issues with basic structures.
Yes, I am trying to get the information of the skins which belongs to the composite structures. Sometimes there is no problem, but sometimes it just disappears. It seems like if there was a solid element operation on the wall, then it lost its information of materials in the IFC file for some reasons. (For example a copy of the very same wall, but with a solid element operation on it.)
Still experiencing these things and @hybrid was very helpful, but haven't found a proper solution on the issue yet. According to @hybrid and my latest experiences, proper setup of classification is crucial, but I am still having problems with composites.

[Minh Nguyen · Accepted solution]

Dear All,

Thank you very much for your discussion on this topic!

Based on the screenshots and info, the Composite structure seems to be exploded upon IFC export. So the wall fell apart into Building Element Parts which are the skins as separate elements.

We can change it in the Geometry Conversion tab in the Translator Settings

I'm wondering if this is the problem?

Looking forward to hearing from you!

Best regards,

Minh

[Norbert Pinter]

Dear Nguyen,
Thank you for your comment, it helped a lot!
This was one of the reasons of the problem and now it seems good when I am exporting it to IFC.