Industry Foundation Classes (IFC)

IFC (Industry Foundation Classes) is an open file format for sharing BIM data across different software platforms. Developed by buildingSMART International (formerly IAI), IFC enables interoperability between Revit, Tekla, Bentley, ArchiCAD, and other BIM authoring tools. The current widely-used version is IFC4 (2013), with IFC4.3 specifically for infrastructure (rail, road, bridges). Indian BIM projects increasingly use IFC for inter-discipline data exchange and submission to government / client review platforms.

IFC structure: (a) Object class hierarchy — IfcWall, IfcBeam, IfcColumn, IfcSlab, IfcStair, IfcDoor, etc. — covering all building elements with standardised properties. (b) Property sets (PSets) — predefined property templates for each object class (e.g., wall load-bearing, fire-rating, material). (c) Geometry — explicit (B-Rep) or implicit (parametric) geometric representation. (d) Relationships — element-to-element, element-to-space, element-to-classification. (e) Document references — links to related drawings, specifications. The full IFC4 schema has over 800 object classes covering virtually every building element.

IFC use in Indian construction: (1) Inter-software exchange — Revit architectural model exported to IFC, imported into Tekla for steel detailing. (2) Submission to government — UP RERA mandates IFC submission for projects above 10,000 m². (3) Client review — federated IFC models in viewers (BIMvision, BIMcollab, Solibri) for non-software-specialist review. (4) Facility management — handover IFC for ongoing operations and maintenance. Limitations: (a) IFC import-export is lossy — geometry may have small inaccuracies; properties may not transfer completely; (b) Not all software supports IFC well (Revit and Tekla good; some others poor); (c) IFC is standardised but vendor implementations vary. Indian best practice: (a) Use IFC for inter-discipline exchange and federation; (b) Don't substitute IFC for native authoring — keep authoring in native (Revit, Tekla); (c) Use specialist viewers (Solibri, Navisworks) for clash detection and validation; (d) Test IFC roundtrips before relying on them for important deliverables.