Revit User Import Capability - IFC4

[Aaron Bourgoin]

What does a Revit user do to import an IFC 4 file. Autodesk and Revit sites Bothe say that Revit can import an IFC4 file, but can only import IFC 2x3.

If we export IFC4 files, can they convert these in a different application for use in their projects? If yes, what?

[MF BIM]

If I recall right, IFC4 imports are possible starting from Revit 2022 so they may just need to use a later version.

[Aaron Bourgoin]

If have no control over which version of Revit my teammates are using. That's why I'm asking if there are applications that can read IFC 4 and save back to 2x3?

[Jim Allen]

My office uses IFC model transfer with Revit for every project, and we use IFC 2x3.

I have been told by GS support that IFC 4 is not particularly well (consistently) supported by Revit yet, and our experience backs this up.

Even IFC 2x3 has its issues with the ability of Revit to recognise walls, windows, doors (including 2D display of swings) etc, and its ability to insert fittings onto the imported structure.

We had to make our own export filters specifically for Revit MEP to get it to work properly.

Almost every thing works as it ought - but there is a problem with anything using SEOs - cut geometry is ignored.

To get SEO trimmed geometry to display in Revit you need to use boundary representation mode, which breaks other functional requirements.

So if you want genuine interoperability between GS and Revit between disciplines using different software, you can do it, but from our experiments, there is a single limitation with SEOs.

IFC4 is not the optimal solution - we spent days experimenting, and didn't get it to work properly in Revit

[Laszlo Nagy]

According to buildingSMART:

https://technical.buildingsmart.org/services/certification/ifc-certification-participants/

Revit is certified for IFC4 Architectural Reference Exchange Import and Export.

As far as I know, the keyword here is "Reference" because there are other types of IFC4 exchanges as well.

In Archicad, you would have to use the "IFC4 Reference View-based Export" IFC Translator for this (it uses Precise BREP geometry conversion). The other default IFC4 Translator in Archicad is "IFC4 Design Transfer View-based Export" but that one uses extruded geometry export.

You could also use the IFC Add-On for Revit that improves IFC exchange with Archicad.

It would be good to know the exact issue (e.g. certain element types are not converted properly) so we can provide better answers.

[Jim Allen]

In my office nothing we tried with IFC4 worked properly with Revit.

Despite what Autodesk or its certification say, my colleagues and I couldn't get it to work, even with the Graphisoft Revit IFC plugin and assistance from GS UK TEch support - who are stellar.

IFC2x3 was difficult enough - we must have tried all the options, and almost every time we had some issue or other. Sometimes 2d door swings were missing, sometimes walls weren't able to receive Revit electrical fittings, sometimes SEOs won't display, sometimes windows and doors had other display issues.

Unless people have tried it personally and achieved success with models with any degree of complexity (for example complex profile walls, SEOs etc) and can share exactly what their results have been so we know what to do to get IFC 4 transfer to work - quoting standards is just unhelpful.

[Laszlo Nagy]

Hi Jim,

Did you guy report these issues? I am sure if you report it to Graphisoft, they will do whatever they can on their side for the exchange to work with IFC 4.

[Jim Allen]

Hi Laszlo,

The approach we are using is one that was recommended by GS support - as I mentioned above.

I was told quite specifically that IFC4 exchange with Revit just doesn't work very well.

I don't know if there is some internal GS tech support knowledgebase that has tested exactly what works and doesn't with Revit IFC export, but it's not enough just to import a file into Revit, you need to be able to do something with it, and if no-one has actually tested placing Revit electrical fittings on imported IFC walls, you won't know if it actually works properly.

Just seeing the geometry in Revit which looks kind of right (2D door swing display issue aside) isn't enough. I was able to sit in the same room as my Revit using colleague while he was trying add electical fittings to see what was working.

What we do know, is that using certain IFC export options we are able to get Revit to treat imported IFC walls pretty much the same as native Revit ones, which is great, and is the main criterion.

However, from our tests (this does take several hours) we were only able to do it with IFC 2x3 and without boundary representation, so no SEO cuts.

It's entirely possible we were missing something, but eif so I would be surprised, because we were quite methodical in our testing.

[Karoly Horvath]

This is interesting.
I have been using IFC 4.0 for over a year.
We specifically changed the format to improve speed.
For example:
Export IFC 2x3 from Archicad 25 takes 35min.
Export same model to IFC 4.0: 3 min
Revit import:
The trick is: In Revit you should not try to open the IFC 4.0 model. You should Insert it instead.
The model is inserted in 20 minutes. While Revit inserts the IFC 4.0 model, it generates a rvt file in the folder where you had the IFC file.
The generated rvt file is perfectly usable for background and for clash detection. 

[Laszlo Nagy]

Karoly,

Do you mean to "Link an IFC" file in Revit? I think that is what the command is called.