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.
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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