Material thickness ifc

[Ieva]

Hello,

I have a problem exporting material thickness to ifc. The filter is okay - other models are exporting correctly with it, but one of the models export materials without any thickness (I can see materials, but their thickness is 0). Can't find what's wrong. Do you have any ideas how to export them? or any clue what's wrong with the model?

I also get this error when exporting (you can see it in attached file)

[Laszlo Nagy]

So you are saying that a Building Material has a non-zero thickness in the model (in a Composite perhaps) and in the exported IFC its thickness becomes zero? Can you show screenshots of the structure in Archicad and the IFC file and its settings in Archicad?

About the error message:

maybe you have Building Materials which have their "Partificated in Collision Detection" checkbox unchecked?

[virginija_r]

Hi, Laszlo,

I'll add a bit to Ieva's inquiry: checkbox is checked in all materials, so I guess this should not be a problem. The problem seems to be with IfcCovering (Ceiling, Cladding, Flooring) - it exports the Material tab, but the thickness is still 0mm, where IfcWall is exported normally. I'm adding a couple of printscreens below.

Thank you in advance!

[Laszlo Nagy]

OK, I see, so the geometry is actually correctly exported to IFC (the element has thickness), but the thickness Properties report 0 mm for thickness for some reason.

I would say that this is a bug so I will report this to Graphisoft for investigation.

[Minh Nguyen]

Dear All,

Thank you very much for sharing this problem! We have consulted it with our developers and it turned out to be a limitation of the IFC Schema and Solibri:

The parametric composite structure can only be preserved in IFC for IfcWall and IfcSlab via IfcMaterialLayerSetUsage. Solibri shows the thickness value from that, if it's present, otherwise it shows 0.
So this is a bug of Solibri (showing 0) and a limitation of the IFC schema (disallowing this structure for other types).

I hope this explains the situation. Please let me know if you have any further questions!

Best regards,

Minh

[JSN]

Dear Minh,

Thanks for your provided explanation - this behaviour is still valid till the present day for models generated by AC. Interestingly is that in the provied screenshot above the walls indeed have thickness and it solely seems to be a covering issue whilst I get this problem all the time ... 

However, if this is a IFC limitation, why is it then working correctly for some models - even those exported from Revit?

I did also ask Solibri about this issue refering to your hint that this might be a bug but have not yet gotten a reply. Still would be interessting to hear what your devs 

[JSN]

Hi Minh once again,

More confusion arises as I have received a model today generated by (Archicad 26.0.0 AUT FULL Windows version (IFC add-on version: 4022 AUT FULL) which is indeed showing for some elements the correct thickness in Solibri ....

When I tried to recreate this with the same version on my side I failed ....

Tried all kind of setting combinations but did not succed.

Then I realized that also in the file I received this is not working for all elements as some indeed have a zero thickness.

So while I have already adressed this to the Solibri guys I am curious what's your expertise on this as this becomes more and more mysterious to me ...

EDIT:
Ok, I realized that Solibri seems only to show the thickness correctly if the Geometry Conversion in Archicad is set to Extrusion -> so BREP does not work with Solibri, can you confirm/elaborate if this is a technical limitation or if there are any other ways to get this to work with BREPs?

Best,