IFC (Industry Foundation Classes) is the open neutral file format for BIM data exchange. Standardised by ISO 16739-1:2024 as IFC 4.3 ADD2. This page explains the schema layout, key entities for civil/structural engineers, version differences, and the export profile to use from Revit.
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Spatial Structure (the IFC backbone)
Every IFC file follows this hierarchy. Memorise it — clash detection and queries depend on it.
IFC Entity Describes Example Notes IfcProject The whole project — root container 1 per file Holds units, geographic reference, header info IfcSite The physical site / parcel of land Usually 1 per project Geo coordinates, terrain, boundaries IfcBuilding A single building 1 or more per site Building name, type, address IfcBuildingStorey A floor / level Multiple per building Elevation, name (Ground, First, Roof) IfcSpace A room / space Multiple per storey Holds room number, area, occupancy
Building Elements (Architecture)
IFC Entity Describes Example Notes IfcWall / IfcWallStandardCase Wall element Brick wall, AAC wall, partition StandardCase = simple extrusion; IfcWall = complex IfcSlab Slab — floor or roof RCC floor slab, precast plank PredefinedType: FLOOR / ROOF / LANDING / BASESLAB IfcRoof Roof assembly (multiple slabs) Pitched roof Aggregates IfcSlab elements IfcDoor Door — opening assembly Single-leaf, double-leaf, sliding Has IfcDoorType for the door catalog IfcWindow Window — opening assembly Casement, fixed, louvre Has IfcWindowType IfcStair Stair assembly (flights, landings, railings) RCC staircase, steel stair Aggregates IfcStairFlight + IfcRamp IfcRamp Ramp Disabled access ramp PredefinedType: STRAIGHT_RUN / TWO_STRAIGHT_RUN / SPIRAL IfcCovering Finish: floor / wall / ceiling cover Tiles, plaster, paint, ceiling PredefinedType: FLOORING / CEILING / CLADDING
Structural Elements
IFC Entity Describes Example Notes IfcBeam / IfcBeamStandardCase Horizontal load-bearing member RCC beam, steel ISMB, plate girder Uses IfcSectionProperties for cross-section IfcColumn / IfcColumnStandardCase Vertical load-bearing member RCC column, steel column Uses IfcSectionProperties IfcMember Generic structural member Truss member, brace, strut PredefinedType: BRACE, STRUT, TIE, RAFTER, MEMBER IfcPlate Steel plate Gusset, base plate, splice plate — IfcFooting Footing / pile cap Isolated footing, raft, strip footing PredefinedType: ISOLATED / STRIP / RAFT / PAD IfcPile Pile Bored cast-in-situ, driven, micropile PredefinedType: BORED / DRIVEN / etc. IfcReinforcingBar Single rebar Y16 bar, T25 bar BarLength, NominalDiameter, BarRole IfcReinforcingMesh Welded wire mesh Slab top mesh MeshLength, MeshWidth, BarSpacing IfcTendon Prestressing tendon Post-tensioned slab cable — IfcStructuralLoadCase Single load case (DL / LL / WL / EQ) Used by analytical model exports Read by analysis tools
MEP (Mechanical, Electrical, Plumbing)
IFC Entity Describes Example Notes IfcPipeSegment Pipe — straight segment 150 mm DI water main Most common MEP entity IfcPipeFitting Bend, tee, reducer — PredefinedType: BEND / TEE / REDUCER / etc. IfcDuctSegment Duct (HVAC) 600×400 supply duct — IfcCableSegment Cable / cable tray 1.5 sq mm copper — IfcFlowTerminal End device — diffuser, fixture, light Wall diffuser, sink, ceiling light PredefinedType has many variants IfcFlowFitting Generic flow fitting Flow combiner, bend —
Infrastructure (NEW in IFC 4.3)
These entities only exist in IFC 4.3 ADD2 and later — IFC 4.0 and IFC 2x3 cannot represent them
IFC Entity Describes Example Notes IfcRoad Road / highway — Aggregates pavement layers, alignment IfcRail Rail track — Aggregates rail, sleeper, ballast IfcBridge Bridge — Deck, piers, abutments IfcTunnel Tunnel — Lining, cross-passages IfcMarinePart Marine works Wharf, quay, breakwater — IfcAlignment Linear alignment Road / rail centerline Horizontal + vertical + cant
IFC Versions — Which to Use
IFC Entity Describes Example Notes IFC 2x3 Released 2007 — Avoid for new work — many entities missing. Only use for legacy interoperability. IFC 4 / IFC 4.0 Released 2013, ISO 16739:2018 — Default for buildings. Most authoring tools support fully. IFC 4.1 Added rail alignment basics — Transitional IFC 4.3 ADD2 ISO 16739-1:2024 — USE THIS for any project with infrastructure (roads, rail, bridges, tunnels, marine) IFC 5 (in development) Coming soon — complete redesign — Not yet released; do not use
Revit IFC Export Profiles
IFC Entity Describes Example Notes IFC 4 Reference View Read-only handover view Used for FM handover Recommended for client deliverables IFC 4 Design Transfer View Bi-directional design exchange Architect → Structural Use for design coordination IFC 2x3 Coordination View 2.0 Legacy coordination When working with old tools Avoid for new projects Custom MVD Project-specific Model View Definition Defined in BEP Best for specialised use cases
Notes
• IFC 4.3 ADD2 (ISO 16739-1:2024) is the current schema — supports buildings AND infrastructure
• For new projects with rail, road, bridge, or tunnel content, IFC 4.3 is mandatory — earlier versions cannot represent these
• Always validate IFC exports with the buildingSMART certification tool before sharing
• Revit's default IFC export is often IFC 2x3 — change to IFC 4 Reference View manually
• For Indian projects, IFC + Uniclass 2015 classification is the most common open-data combination
• IfcPropertySet bundles custom properties — use a consistent property template across the project
• Memorise the spatial structure (Project → Site → Building → Storey → Space) — every IFC query starts here
• Schema specs free at: technical.buildingsmart.org/standards/ifc/
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