What an IFC file holds
An IFC file describes a building as a list of records. A record can be an element, such as a wall, a door or a space, a property set that an element carries, a material, a classification, or a relationship, for example that a door is in a wall, or that a wall is on a storey. Elements have a class, such as IfcWall, and an identity, a GlobalId, which a tool should keep the same from one export to the next. A model can also carry the shapes of its elements, which IFC Checker draws in the 3D view, but a check reads the information.
The file is plain text in the STEP format. It starts with a header that names the schema it is written in, and has a DATA section of numbered records. Model health checks that every record can be read and that the file matches its schema.
IFC and IDS
IFC says what a model contains. IDS says what a model must contain. IFC Checker reads the first and tests it against the second.
Try it in IFC Checker
- Add an IFC model on Check. The row of the model says which IFC schema its header names.
- After the check, find the schema again in the Schema column of the Model table.
Where the schemas are documented
buildingSMART publishes every release with its documentation. The page that lists them all is buildingSMART: IFC schema specifications. The three releases IFC Checker reads:
- IFC 4.3 documentation, the release IFC Checker calls IFC4X3_ADD2, for buildings and infrastructure
- IFC4 documentation, Addendum 2, Technical Corrigendum 1
- IFC2X3 documentation, Technical Corrigendum 1, the older release that many tools still export
- buildingSMART: Industry Foundation Classes (IFC), the standard and its releases