What is an IFC File? BIM Format Explained for Survey Delivery

IFC (Industry Foundation Classes) is an open, vendor-neutral file format for Building Information Modelling (BIM) data, standardised as ISO 16739. It allows building models created in one software platform (Revit, ArchiCAD, Tekla) to be opened and used in another without losing geometric or property information. For surveyors, IFC matters because scan-to-BIM workflows are increasingly common: you capture a building with a laser scanner, a modeller builds the BIM, and the deliverable is an IFC file. Understanding what IFC contains, how it works, and how to share it with clients will become essential as BIM mandates expand globally.

I’m seeing IFC files come across my desk more frequently every year. Five years ago, surveyors rarely touched BIM. Now, scan-to-BIM is a standard service offering, and clients expect to receive IFC alongside traditional survey formats. Here’s everything you need to know.

Why IFC exists

The construction industry has a fragmentation problem. Architects use Revit or ArchiCAD. Structural engineers use Tekla or Revit Structure. MEP engineers use their own tools. Contractors use Navisworks, Solibri, or BIMcollab. Owners might use something else entirely.

Each of these applications has its own proprietary file format. A Revit .rvt file can’t be opened natively in ArchiCAD. An ArchiCAD .pln can’t be opened in Tekla. This creates data silos and forces teams to re-model information that already exists.

IFC solves this by providing a common language. It’s the “PDF of BIM” — a standardised format that any BIM application can read and write, enabling information exchange without requiring everyone to use the same software.

The format is developed and maintained by buildingSMART International, and it was adopted as an international standard: ISO 16739:2013 (updated to ISO 16739-1:2024).

What’s inside an IFC file

An IFC file contains far more than geometry. It’s a structured data model that describes:

Building elements

Every physical component in the building is represented as a typed object:

Each element knows what it is. A wall isn’t just a box — it’s an IfcWall with material, fire rating, thickness, and other properties.

Geometry

IFC supports multiple geometric representations:

• Extruded profiles — A 2D profile swept along a path (most common for walls, columns, beams).
• Boundary representation (B-rep) — Surfaces defined by faces, edges, and vertices (for complex shapes).
• Triangulated meshes — For curved or irregular geometry.
• Constructive Solid Geometry (CSG) — Boolean operations (union, subtract, intersect) on primitive shapes.

Most BIM authoring tools export a mix of these, with simple elements using extrusions and complex elements using B-rep or mesh.

Properties and metadata

Every element can carry property sets (Psets) — structured collections of named values:

This is what makes IFC different from simple 3D model formats like OBJ or GLB. An OBJ file contains geometry — triangles and vertices. An IFC file contains building intelligence: what each element is, what it’s made of, and what its properties are.

Spatial hierarchy

IFC organises elements in a spatial hierarchy:

IfcProject
  └── IfcSite
        └── IfcBuilding
              ├── IfcBuildingStorey (Level 0 / Ground)
              │     ├── IfcWall
              │     ├── IfcDoor
              │     ├── IfcColumn
              │     └── ...
              ├── IfcBuildingStorey (Level 1)
              │     ├── IfcWall
              │     ├── IfcWindow
              │     └── ...
              └── IfcBuildingStorey (Roof)

This hierarchy means you can query “show me all walls on Level 1” or “list all doors in Building A” without parsing geometry — the structure encodes the relationships.

Relationships

IFC explicitly models relationships between elements:

• IfcRelContainedInSpatialStructure — Which storey an element belongs to.
• IfcRelConnectsPathElements — How walls connect at junctions.
• IfcRelFillsElement — Which wall a door or window is hosted in.
• IfcRelVoidsElement — Openings cut into walls for doors/windows.
• IfcRelAggregates — Assemblies of elements (e.g., a stair as an aggregate of flights and landings).

IFC versions

IFC 2x3 remains the most widely supported version. Most software imports and exports it reliably. IFC4 is technically superior with better geometry support and cleaner property definitions, but adoption is still catching up. If unsure, export as IFC 2x3 for maximum compatibility.

IFC4.3 is significant because it extends the schema to infrastructure — roads, railways, bridges, and waterways. This brings IFC into the civil engineering domain, which was previously dominated by proprietary formats like LandXML and Bentley’s DGN.

Who creates IFC files

BIM authoring software

Scan-to-BIM workflows

This is where IFC intersects most directly with surveying. The typical workflow:

1. Capture — Survey the building with a terrestrial laser scanner (Leica RTC360, FARO Focus, Trimble X7) or mobile scanner. The output is a point cloud, typically in E57 format.

2. Register — Align multiple scan positions into a single coordinate system. This happens in the scanner’s software (Leica Cyclone, FARO Scene, Trimble RealWorks).

3. Model — Import the registered point cloud into Revit, ArchiCAD, or another BIM platform. A modeller traces over the point cloud, creating BIM elements (walls, floors, columns, doors) that match the as-built conditions.

4. Export — Export the completed model as IFC for delivery to the client.

5. Deliver — Share the IFC file with the client for facility management, renovation planning, or compliance documentation.

The survey company’s role is typically steps 1-2 (capture and register), sometimes extending to step 3 (model) if they have in-house BIM capability. The deliverable to the client may be the point cloud, the IFC, or both.

Level of detail (LOD)

Scan-to-BIM models are classified by level of detail:

Most scan-to-BIM deliverables target LOD 200-300. LOD 300 means walls are modelled at their actual thickness, doors are correctly sized and positioned, and structural elements match the as-built condition within a specified tolerance (typically 10-25 mm).

Why surveyors encounter IFC

BIM mandates

Governments worldwide are mandating BIM for public projects:

• United Kingdom — BIM Level 2 mandatory for central government projects since 2016. ISO 19650 adopted.
• Singapore — BIM submission required for regulatory approval since 2015.
• Scandinavia — BIM widely mandated for public infrastructure.
• Australia — State-level mandates emerging (Transport for NSW, Victoria).
• United States — GSA requires BIM for new buildings. State DOTs increasingly requiring BIM for infrastructure.

Where BIM is mandated, an as-built IFC deliverable is often required at project completion. Surveyors who can deliver scan-to-BIM are positioned to serve this growing market.

Renovation and heritage

Existing buildings being renovated need an accurate as-built model before design can begin. Laser scanning provides the measurement, and IFC provides the delivery format for that model.

Heritage buildings, in particular, benefit from BIM documentation — the model captures not just geometry but material types, condition assessments, and intervention history.

Facility management

Building owners use IFC models for ongoing maintenance, space management, and asset tracking. The as-built IFC becomes a living document that’s updated as the building changes.

IFC file sizes

IFC files can be large, especially for detailed models:

File size depends on geometric complexity, level of detail, and how efficiently the authoring software generates the IFC export. Revit IFC exports tend to be larger than ArchiCAD exports for equivalent models because of differences in geometry representation.

How to view IFC files

Desktop viewers

Browser-based viewing

Most of the free desktop viewers require installation, which creates the same delivery problem as every other spatial format: your client doesn’t have the software.

Swyvl renders IFC files directly in the browser using xeokit, an open-source BIM rendering engine. Upload an IFC, share the link, and the client can explore the model — orbit, section, toggle storeys, select elements, and view properties — without installing anything.

This is particularly valuable for scan-to-BIM delivery. The client receives a link, opens it on any device, and can inspect the model immediately. No Revit licence required. No BIMvision download. Just a browser.

For more on sharing 3D models in the browser, see How to Share a 3D Model Online.

Common issues with IFC files

Geometry artefacts

IFC export from Revit often produces geometry that looks slightly different from the native model. Curved walls may be faceted, junctions may have small gaps, and some elements may be positioned slightly off. This is because the IFC geometry representation differs from Revit’s internal representation.

Fix: Review the IFC in a viewer before delivery. Adjust export settings — Revit’s IFC export options include level of detail for curved geometry.

Missing properties

Not all properties in the BIM authoring software transfer to IFC. Custom parameters, shared parameters, and some system parameters may not map to standard IFC property sets.

Fix: Use the IFC export mapping table in your authoring software to explicitly map properties. In Revit, this is the IFC Export Classes mapping file.

Large file sizes

Complex models produce large IFC files that are difficult to email or transfer via traditional methods.

Fix: Upload to a platform that handles large files. Swyvl supports multi-part upload for files of any size and renders IFC directly in the browser. See How to Send Large LiDAR Files for general guidance on large file delivery (the same principles apply to large IFC files).

Version incompatibility

An IFC4 file opened in software that only supports IFC 2x3 will fail or display incorrectly.

Fix: Check what version your client’s software supports. When in doubt, export as IFC 2x3.

Coordinate system issues

IFC files use a local coordinate system defined by the IfcProject and IfcSite entities. If the model was created in a local coordinate system (common in Revit, which struggles with large coordinates), the IFC may not align with survey data in a projected coordinate system.

Fix: Set the survey point and shared coordinates correctly in Revit before export. Include a coordinate system note in your deliverable documentation.

IFC vs other 3D formats

The key distinction: IFC carries building intelligence. Exporting to GLB or OBJ for web viewing loses all the property data, element classification, and spatial hierarchy. This is why dedicated IFC viewers (like Swyvl’s xeokit-based viewer) are important — they preserve the BIM data that makes the model useful, not just viewable.

Summary

• IFC is the open standard for BIM data exchange, standardised as ISO 16739 and maintained by buildingSMART.
• It contains building elements, geometry, properties, and relationships — far more than simple 3D geometry formats.
• IFC 2x3 is the most compatible version, though IFC4 is the current standard and IFC4.3 extends coverage to infrastructure.
• Surveyors encounter IFC through scan-to-BIM workflows: capture with laser scanners, model in Revit or ArchiCAD, deliver as IFC.
• BIM mandates are expanding globally, making IFC competency increasingly important for survey firms.
• For client delivery, browser-based viewing eliminates the need for BIM software. Upload the IFC to Swyvl and share a link.
• Common issues include geometry artefacts, missing properties, and coordinate system confusion. Review exports before delivery.

For more on survey file formats, see What File Formats Do Drone Surveys Produce?. For sharing other spatial formats in the browser, see How to Share a 3D Model Online.