Why is my model broken and has holes in it?

In some cases, this is due to IFC export settings. To fix this when exporting to IFC:
- In Revit, set Level of detail as high
- In ArchiCAD, select Exact geometry export

Some modelling software may have problems with normal directions when exporting to IFC. This causes flipped normals; you can see through the faces that are facing outwards. You can try to fix this by reversing the problematic normals in your 3D application before exporting.