- Watch out
- What it costs
- Experienced readers
- Remember
- In BIMpedia
When you export IFC, you hand your model to people who don't have your software: the coordinator, the fire engineer, the estimator, a checker that runs every week. They see only what the export put in the file. Two models that look identical on your screen can produce very different IFC files.
The structural engineer exports IFC with the default settings and sends it. The coordinator's clash test finds nothing between ducts and beams: the beams came out as IfcBuildingElementProxy, and the test only looks at IfcBeam. The clashes are found on site.
The engineer maps each category to its IFC class once, saves the settings with the project, and opens every export in an inspector before sharing it: beams are IfcBeam, every element sits in a storey, the agreed properties are there. The clash test finds the 40 duct–beam clashes in week two.
What the export settings decide
- 1HeaderSchema, application, view
- 2Spatial structureStoreys and containment
- 3ClassesProxies, names, duplicates
| Setting | Why it matters to others |
|---|---|
| Category → IFC class mapping | Checks, clash tests and take-offs select by class |
| Property set mapping | Checks look in standard or agreed sets |
| Storeys and spatial structure | Schedules, 4D and site views filter by level |
| Classification | Cost and specifications map by code |
| Coordinates | Federated models must line up |
IFC is the open, vendor-neutral format for BIM data. Each element belongs to a class (IfcWall, IfcDoor, IfcBeam) and carries property sets: named groups of properties. buildingSMART defines common sets for each class, such as Pset_DoorCommon with FireRating, IsExternal and more. Projects can add their own named sets.
Test before you share
After every export, take five minutes:
- Open the file in a viewer or inspector.
- Count the classes: any proxies? Anything missing?
- Pick a door, a wall and a room: are the agreed properties there, in the right set?
- Check the storeys: does everything sit on a level?
Open the IFC Inspector and click Try the sample model if it isn't loaded. Answer:
- Are there any IfcBuildingElementProxy elements?
- Which property set holds the doors' fire rating?
- Do all elements sit in a storey?
Key takeaways
- Export settings decide the IFC class, the property sets and the storeys of every element; defaults are rarely right for a project.
- Elements exported as IfcBuildingElementProxy are invisible to most checks and take-offs.
- Agreed properties belong in standard sets (Pset_DoorCommon.FireRating) or in the project's named set, not wherever the exporter puts them.
- Save the export settings with the project and use the same ones every time.
Your notes
Related tool
Open an IFC file in the browser: structure, elements, properties and required-property checks.
Open IFC Inspector →