Blender BIM + Archipack/removing IFC elements

I have modelled two walls with Archipack, with one I applied the modifier and the other I did not.

When exporting to IFC I get some weird results, but that's not the point of my question.

The one which looks weird I didn't apply the wall modififier.
I wanted to test if I could remove a void.
I used the remove void button, instead of delete;

Which worked in Blender.
When exporting to IFC it says the IFC element does not exist. Here the console output

Now this is a small example. But as I understand the IFC Schema is built on a hierarchy, I just can't delete elements in Blender and export it to IFC again. Because it misses relationships which were already exported.
What is a good workaround to delete elements which are dependent on other elements? Void being the most common I think.

I would like to understand this., why does BlenderBIM modify the IFC directly? Isn't it more convenient to built a whole new IFC every time when exporting to prevent things like this?


  • More a general question, which Blender modifiers will and won't work when exporting to IFC? And why?

  • I have fixed your issue which will be available in tomorrow's build. Since the last release, there is now a focus on stabilising native authoring. You will likely see a lot of these simple "authoring" fixes in the next release (just today see fix and fix and fix). I have also made it work so that you can just delete an opening instead of manually pressing the remove void button - see fix.

    In the short term, it is indeed far easier to build a whole new IFC every time. In the first year of the BlenderBIM Add-on, in fact this was the approach I used. In the long term, however, I quickly discovered this is impractical (at the start of this year, I rebuilt everything from scratch, and I do not regret it). With the "build it every time" method, 1) Export times become huge - where other proprietary apps take hours to export, the BlenderBIM Add-on finishes in mere seconds. 2) There is huge data loss. Not everything translates 1:1 to the Blender world. The BlenderBIM Add-on is the only solution that has in theory zero data loss (apart from these relatively straightforward bugs which we are sorting out). 3) Development scalability is unachievable in a monolithic import/export function, but with this approach the BlenderBIM Add-on is the only solution that can confidently implement 100% of the IFC specification. No other proprietary app comes close.

    The downside, of course, is that there is a huge amount of work to do to get basic "from scratch" authoring working. The good news is that the majority of the foundation has been built, and that whereas it hasn't been a huge priority in the past (personally I mostly deal with IFCs from other software), I have now made it a focus and have a strategy.

  • There are viewers, importers and exporters, but blenderbim is an IFC editor

  • @Moult
    Thank you for the elaborate explanation. I continue to be impressed by your work.


    There are viewers, importers and exporters, but blenderbim is an IFC editor

    Not secretly also an IFC creator? :-)

  • @brunopostle

    There are viewers, importers and exporters, but blenderbim is an IFC editor

    Not secretly also an IFC creator? :-)

    This will happen in time, but the usefulness of this approach is that multiple creative tools (freecad, archipack, blender itself, etc..) can interoperate.

  • edited September 9


    There are viewers, importers and exporters, but blenderbim is an IFC editor

    I just loaded an IFC produced in Sketchup into BlenderBIM and added quantities and properties. It's already extremely useful indeed. The basic Blender functionality like 'splitting by loose parts' and 'array modifiers' cause such a fast workflow compared to what I know in Revit.

  • Just tested the latest build of BlenderBIM:
    Nice to see it working :-).

    And the void deleted and exported to IFC again.

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