Ifc export wrong scale

I use “IFC Manager” for ifc export. Lately Revit users complain my model sometimes comes in at about 1/3 of correct size. So not the inch difference, but reduced so that a meter is now a foot (12 inches) I have not found any pattern of what could be wrong on my part or from the Revit users.

Strangely they report the size is correct in Solibri viewer.
I Attach the ifc where both buildings are supposed to be 24 meters deep
BYGG3.ifc.zip (1.1 MB)

Alright: it seems maybe if I have my “model info: Units” set to mm instead of meters this does not happen, not that I understand any of it.

Also some revit users say the file is empty…


Could be that the Revit importer doesn’t work well with only the IFCUnits set to metre and that a IFCUnitconversion is missing in the export of the ifc manager.
The not seeing the model can be related to the view range in the floorplan, this specific model is floating in the air.
(Imported as link in Revit 2022, model is 1/3…)
Maybe, if you attach the .skp file, @brewsky can have a look at it.

Yes, interesting issue, if you can share the Sketchup model I will look into it.

I’ve been having some issues with DWG export too, sometimes. From Skalp exports. I haven’t investigated what’s happening yet though, so didn’t make a report. I wonder if it’s related.

When communicating with Revit and Archicad my experience is that it’s best to stick to a single IfcSite and a single IfcBuilding in the model. Archicad only imports the first building it finds and Revit reduces multiple buildings to generic objects if I remember correctly.
IfcManager automatically creates a single default site and building if none of these are defined in the model, so when you don’t need any specific building name or other properties it’s easiest to just start the main building structure with IfcBuildingStoreys.

Really weird, I can reproduce the issue. When setting Sketchup units to ‘meters’, Revit 2022 seems to import any model a third of the size.
Both the buildingSMART and KIT IFC validators give zero issues with this model.
Untitled2.zip (1.7 KB)

I found it!
There’s a bug in the IFC manager.
Length unit should be:


and was:



Can you try the new version of IFC Manager? Release SketchUp-IFC-Manager 4.3.1 · BIM-Tools/SketchUp-IFC-Manager · GitHub



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This is fantastic. I will download and test. Thanks

@brewsky Thank you for the quick response in fixing the meter issue. I wonder: is there a way to set the origin of the ifc export to the axis system of the scene, instead of origin in model ? That would be really handy.

Interesting suggestion.
Should that be an option, or default behaviour?
I generally stick with the model origin and place rotated models as linked components.

I guess we all work differently, and I work also differently from project to project. Sometimes the project team insist on local origo at the corner of the building (on the reference grid), but I try to set it to the nearest reference to the map, so that I can present coordinates in Layout to tell where to put the building. If you have the site plan and the building in two different files that is not an issue of course. But if you have them in the same file, and the team wants origo in a building corner, then you have to orient your site wrong:-), in order to get the right ifc orientation.

Export option for model axes will be in the next release: Add option to export model axes transformation · BIM-Tools/SketchUp-IFC-Manager@eac1dd1 · GitHub

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I guess we are getting a bit off topic here, might be better to discuss feature requests here: SketchUp IFC Manager extension - #22 by brewsky :wink: