Open BIM and IFC: What They Actually Mean and Why Your Projects Need Them

“Just send the IFC” is something you’ll hear on any multi-discipline BIM project. But most people who say it - and many who do it - don’t fully understand what IFC is, what it preserves, what it loses, and when you should (or shouldn’t) use it.

This guide cuts through the buzzwords and explains Open BIM and IFC in practical terms: what problems they solve, how they work in real project coordination, and when native file exchange is actually the better option.

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What Problem Does Open BIM Solve?

The core problem is simple: different disciplines use different software, and those software tools don’t natively understand each other’s files.

Your architect uses Revit. The structural engineer uses Tekla. The MEP consultant uses MagiCAD or Plancal Nova. The facility manager uses Archibus. The contractor uses Navisworks or Solibri for coordination.

Without a common exchange format, every handoff between these tools requires either:

• Everyone using the same software (expensive, impractical)
• Manual re-modelling of received data (slow, error-prone)
• 2D drawings as the coordination medium (defeats the purpose of BIM)

Open BIM is the principle that project data should be exchangeable between any compliant software, regardless of vendor. IFC (Industry Foundation Classes) is the file format that makes this possible.

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IFC: What It Actually Is

IFC is an open, vendor-neutral data schema maintained by buildingSMART International. It’s not just a 3D geometry format - it’s a structured data model that describes:

• Geometry (shapes, positions, spatial relationships)
• Properties (material assignments, fire ratings, U-values, costs)
• Relationships (which wall belongs to which storey, which pipe connects to which fitting)
• Classification (Uniclass, OmniClass, or custom systems)

Think of IFC as a standardised language for buildings. When you export a Revit model to IFC, you’re translating from “Revit language” to this common language. When someone opens that IFC in Tekla or Solibri, they’re reading it back.

IFC Versions That Matter

Version	Status	Key Features
IFC 2x3	Widely supported, still common	The “safe” option - almost every BIM tool reads it reliably
IFC 4	Current standard	Better geometry, MEP support, improved property sets
IFC 4.3	Latest (infrastructure focus)	Adds roads, bridges, rail, tunnels - extends beyond buildings
IFC 4x4	In development	Improved construction sequencing and site modelling

Practical advice: Use IFC 2x3 if your coordination partners haven’t specified a version. Use IFC 4 if your BEP (BIM Execution Plan) requires it or if you need better MEP data fidelity. IFC 4.3 is primarily relevant for infrastructure projects.

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What IFC Preserves (and What It Loses)

This is the part most guides skip, and it’s the most important thing to understand.

What transfers well via IFC:

• Basic geometry (walls, floors, roofs, columns, beams)
• Element classification and naming
• Standard property sets (Pset_WallCommon, Pset_DoorCommon, etc.)
• Spatial structure (Site > Building > Storey > Space)
• Material assignments (name-level, not full Revit material definitions)
• Quantities (areas, volumes, lengths)

What typically gets lost or degraded:

• Parametric relationships - a Revit wall that adjusts to roof slope becomes fixed geometry in IFC
• Custom families - complex Revit families export as generic shapes; parametric behaviour is gone
• View-specific settings - section cuts, visibility overrides, view templates don’t transfer
• Worksharing information - workset assignments, ownership data
• Revit-specific parameters - custom shared parameters may not map to IFC property sets unless explicitly configured
• Rendering materials - texture maps, appearance assets, bump maps

The key insight: IFC is excellent for coordination and data exchange. It’s not a replacement for native files when you need to edit the model.

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When to Use IFC vs. Native Files

This is a practical decision, not an ideological one:

Scenario	Use IFC	Use Native File
Sharing with a different software platform	Yes	Not possible
Clash detection in Navisworks/Solibri	Yes (preferred)	Also works for Revit-to-Revit
Model review by client/contractor	Yes	Only if they have the same software
Coordination between architect and structural engineer	Depends on tools	If both use Revit, native links are better
Archiving the as-built model	Yes (open format, future-proof)	Risky (software may not exist in 20 years)
Ongoing design collaboration within same firm	No	Native is faster and preserves more data
Regulatory submission (where mandated)	Yes	Check local requirements

Rule of thumb: Use IFC for cross-platform exchange and archiving. Use native files for same-platform collaboration where you need full parametric behaviour.

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Setting Up Good IFC Exports from Revit

Most IFC complaints stem from bad export settings, not bad IFC format. Here’s how to get clean exports:

1. Use an IFC Export Setup

Don’t just hit “Export > IFC” with default settings. Go to File > Export > IFC and click Modify Setup. Key settings:

• IFC Version: Match what your BEP specifies (IFC 2x3 or IFC 4)
• Space Boundaries: Set to “1st Level” for energy analysis, “None” for basic coordination
• Export Base Quantities: Turn ON - this includes areas and volumes that receiving software can read
• Export Rooms/Spaces: Turn ON if the receiver needs spatial data

2. Map Custom Parameters to IFC Property Sets

If you have custom shared parameters (e.g., “Fire Rating”, “Acoustic Rating”), they won’t automatically appear in IFC unless you map them. Use the IFC Export Classes and Property Set Configuration to map Revit parameters to standard IFC Psets or create custom ones.

3. Check Your Export with a Viewer

Before sending an IFC to anyone, open it yourself in a free IFC viewer. Open IFC Viewer, BIMcollab ZOOM (free), or Solibri Anywhere will let you verify that geometry, properties, and classifications exported correctly.

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The Real-World Coordination Workflow

Here’s what an Open BIM coordination workflow looks like in practice:

1. Each discipline models in their preferred tool (architect in Revit, structure in Tekla, MEP in MagiCAD)
2. Each team exports IFC on an agreed schedule (weekly or at milestones)
3. IFC files are uploaded to a Common Data Environment (BIM 360, Trimble Connect, or a shared folder with naming conventions)
4. The BIM coordinator fedrates the models in a review tool (Navisworks, Solibri, BIMcollab) - combining all IFCs into one view
5. Clash detection runs identify spatial conflicts (duct through beam, pipe through wall)
6. Issues are logged using BCF (BIM Collaboration Format) - another buildingSMART standard that tags issues to specific model locations
7. Each team resolves their clashes in their native tool, re-exports IFC, and the cycle repeats

BCF is the unsung hero of this workflow. Instead of writing “the duct on level 3 near gridline C-4 clashes with the beam,” BCF captures the exact 3D viewpoint, the elements involved, and the assigned responsibility - all in a format every major BIM tool can read.

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Common Pitfalls

“Our IFC looks wrong” - Usually an export settings issue. Check that you’re exporting the correct view, that elements aren’t filtered out, and that your model has proper level/storey assignments.

“Properties are missing” - Either the parameters weren’t mapped during export, or the receiving software doesn’t display IFC property sets by default. Check both sides.

“Geometry is simplified” - This is expected for complex parametric families. IFC represents geometry as boundary representations (B-rep) or extruded solids, not parametric definitions. The shape should be correct even if it looks different in the viewer.

“File is huge” - IFC files can be large. Use IFC4 (more efficient geometry encoding than 2x3) or ask your BIM coordinator if they need the full model or just specific disciplines/levels.

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The Future: IFC and Digital Twins

IFC’s importance is growing beyond design-phase coordination. As the industry moves towards digital twins - live, data-rich models of built assets - IFC becomes the bridge between design models and operational systems. The as-built IFC model feeds into facility management platforms, energy monitoring systems, and maintenance scheduling tools.

IFC 4.3’s expansion into infrastructure (roads, rail, bridges) signals that buildingSMART is positioning IFC as the universal AEC data format, not just a building coordination tool.

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Building your Open BIM skills? The Archgyan Academy covers BIM coordination workflows, including IFC exchange and clash detection, through practical project-based courses.