File extension
.ifc
Industry Foundation Classes (IFC) format
.ifc files hold Industry Foundation Classes models: an open, vendor-neutral data standard for exchanging Building Information Modeling (BIM) data about buildings and infrastructure across design, construction, and facility tools.
Known meanings
Formats and reference material for .ifc
Industry Foundation Classes (IFC) format
Open buildingSMART data model for BIM exchange of building and infrastructure information
Details
Format notes
Industry Foundation Classes (IFC)
IFC is the open, standardized data model for Building Information Modeling (BIM). Maintained by buildingSMART International and standardized as ISO 16739, it describes the objects that make up a building or infrastructure project — walls, slabs, columns, doors, spaces, systems — together with their geometry, properties, relationships, materials, and classification. Its purpose is “openBIM”: letting different design, analysis, construction, and facility management applications exchange a shared model without depending on any single vendor’s native format.
An IFC dataset is more than geometry. It is an object graph in which each element has a type, a set of properties, and typed relationships to other elements — a wall belongs to a storey, hosts a door, is made of layered materials, and carries fire-rating and load properties. This semantic richness is what makes IFC useful for coordination, quantity takeoff, code checking, and handover, rather than just visualization.
Encodings
The classic .ifc file uses the STEP physical file encoding (ISO 10303-21,
“Part 21”), a readable text format of numbered # instances. The same model
can also be serialized as ifcXML (an XML encoding) and packaged as ifcZIP
(a compressed archive of an IFC or ifcXML file). Tools should detect which
encoding is present rather than assuming plain STEP text from the extension
alone. Several schema versions exist (such as IFC2x3 and IFC4), and the schema
version affects which entities and properties are valid.
Preservation And Exchange Notes
Reliable exchange depends on Model View Definitions (MVDs), which constrain which parts of the schema an exchange uses, and on consistent property sets. For preservation and transfer, record the IFC schema version and MVD, keep units and the georeferencing/placement information, and validate the file against the declared schema. IFC is well suited to long-term archiving because it is an open, text-documented standard, but a receiving tool may still ignore entities outside its supported MVD.
Security Notes
Because a Part 21 file is text with cross-referenced instance IDs, parsers should guard against malformed or circular references, extremely large instance counts, and deeply nested geometry from untrusted files, to avoid excessive memory use or non-termination while resolving the object graph.
Further Reading
- buildingSMART IFC standard:
https://technical.buildingsmart.org/standards/ifc/ - ISO 16739 (Industry Foundation Classes):
https://www.iso.org/standard/70303.html