topic Re: IFC export missing void in Revit Architecture Forum

IFC export missing void

b.soldi4KRGE — Thu, 01 Dec 2022 11:02:30 GMT

Hi all,

I've created an architectural model of a building that I want to export in IFC 2x3 coordination view.

When I open the exported IFC with Solibri I don't find the "Fillings" of the windows. All the windows families created in Revit has a void to created the opening in the wall but these elements are not exported so the analysis software that I need to use after can't read the IFC.

What should I check to make these void be exported?

Thanks!

Re: IFC export missing void

esk0r — Thu, 01 Dec 2022 14:03:44 GMT

Hi,

You'd need to map the void objects' category/subcategory to export to a specific IFC class/type.
This would be done different ways depending on which version of Revit are you using (including which updates).
E.g. see below how I can set a specific subcategory of Windows to not export to IFC, in Revit 2020:

Re: IFC export missing void

b.soldi4KRGE — Fri, 02 Dec 2022 09:42:05 GMT

Hi,

of course I've set all the class/type I need but it doesn't work.

I've tried to identify all the openings related to a window as IfcOpeningElement but nothing has changed.

The strangest think for me is that for one window I can see the filling in Solibri, for all the other not (but the family is the same)

Thank you!

Re: IFC export missing void

esk0r — Tue, 06 Dec 2022 19:00:05 GMT

Hi again and sorry for the late reply!
Would you mind sharing a sample window family that has the voids you mention?
I'd like to test exporting myself before suggesting things that might not be relevant.

Re: IFC export missing void

b.soldi4KRGE — Wed, 07 Dec 2022 08:40:29 GMT

Hi,

attached one of the family.

Thank you for your support!

Re: IFC export missing void

esk0r — Tue, 17 Jan 2023 11:27:26 GMT

Hi! Sorry for the very late reply (have been busy with family and Xmas holidays...)

I finally looked into your window family and found why it isn't exporting the opening in IFC and why you can't see it in "Filling", under "Relations" in Solibri.
The reason is that your window family contains two voids instead of an actual window opening. If you delete the voids and create an opening with the dedicated tool, the family exports to IFC with the opening info under Filling, as you expect.
In order to model the 200mm void above the opening, on the one side of the window (as the old voids were doing), I suggest you create a wall based generic model family with a parametric void (so that you can control its height/width/depth when loaded in project) and place it where needed i.e. above each instance of your revised window family, to complete the missing void of 200mm above the window frame, on the one side of the wall.

Not sure you can feed the "stepped" opening you want into the analysis software, but by using a "proper" opening (instead of multiple voids) in the family you will be able to at least pass on the overall window size.
If you are trying to calculate thermal resistance or U value, I'd treat the upper portion (the 200mm above window that only cuts the wall on one side) as separate wall construction (with reduced wall thickness, as needed).

I hope this helps somehow.

Re: IFC export missing void

b.soldi4KRGE — Tue, 17 Jan 2023 11:59:32 GMT

Thank you,

it's very helpfull to understand the reason behind such a behaviour!

Re: IFC export missing void

Delipro — Tue, 01 Aug 2023 09:19:27 GMT

Hi all,

I have a similar problem with the voids on a family. See the image attached, some voids appears on the IFC but other ones no...could someone tell me what i'm doing wrong?

Re: IFC export missing void

esk0r — Tue, 01 Aug 2023 11:54:26 GMT

Hi,

My first guess is that the void is not cutting the solid geometry. If the void exists in the family, make sure to use Cut Geometry before loading into the project.
You are welcome to share the family here so we can test exporting it and hopefully solve your issue.

Re: IFC export missing void

Delipro — Tue, 01 Aug 2023 12:07:18 GMT

Hi, no the void cuts the geometry....i made some test and in the version 2x2 of ifc i can see the voids but in the version 2x3 i can see some voids but not all voids created. If you see the image i sent, all the voids are cutting the geometry. But thanks for your answer.

Re: IFC export missing void

Delipro — Tue, 01 Aug 2023 12:08:22 GMT

Here the family

Re: IFC export missing void

esk0r — Wed, 02 Aug 2023 11:37:07 GMT

Hi again,
Thanks for sharing the family. I tried to export it and it worked fine first time (see picture). I used Revit 2021 with all the latest updates (incl. for the IFC exporter). Make sure that you have all the updates installed. Also, I used IFC 2x3 Coordination View 2.0 but pretty sure it'd work fine with any other option.

Re: IFC export missing void

Delipro — Wed, 02 Aug 2023 11:55:54 GMT

Thanks for your help. After some tests i found the problem but not the solution. I'm using a personal RTE to create my jobs. If i create a new project with the architectural template (original version of revit) and i make the same process, it's works well and the ifc represents the holes and the color material for each part. So it's not a problem on the family but it's on my template. I will need try to find what is making this situation.