How to Repair Broken IFC Files and Fix Duplicate GUIDs

Duplicate GUIDs, missing storey assignments, orphaned geometry, and corrupt entities — here is how to diagnose and fix an IFC file that refuses to cooperate.

You open an IFC file and the viewer reports errors. A clash tool refuses to load it. An IDS validator throws "duplicate GlobalId". A merge produces wrong element counts. The file is technically valid but practically broken. Here is how to diagnose and repair it without re-exporting from the original authoring tool.

The most common IFC problems

Duplicate GUIDs. Two or more elements share the same GlobalId. IFC requires GUIDs to be globally unique; duplicates break comparison, validation, and downstream data pipelines.
Missing storey assignments. Elements exist in the file but are not linked to any IfcBuildingStorey, so they never appear in floor-filtered views.
Orphaned geometry. Shape representations that are not attached to any element. Invisible in most viewers but bloat file size.
Broken relationships. IfcRelContainedInSpatialStructure or IfcRelDefinesByProperties pointing at entities that no longer exist.
Invalid property sets. Psets with null or malformed values that some tools accept and others reject.
Corrupt geometry. Degenerate solids with zero volume or self-intersecting faces.

Step 1: diagnose with Model Health Check

Always start here. The Model Health Check tool scans the entire file and produces a categorised report:

Critical issues that will break most tools.
Warnings that some tools tolerate but are worth fixing.
Statistics about the model (element counts, schema version, unit system).

Upload the IFC file.
Open Model Health Check and run it.
Read the report top to bottom. Each issue links to the affected element GUIDs and a recommended fix.

Step 2: fix duplicate GUIDs

Duplicate GlobalIds are the single most common IFC quality issue. They usually come from:

Copy-paste in the authoring tool that duplicated elements without regenerating GUIDs.
Exports from non-standard plugins that reuse internal IDs as GlobalIds.
Manual edits to the IFC text with a script that forgot to regenerate IDs.

Repair GUIDs finds every duplicate and assigns a fresh, valid GlobalId to all but one of each duplicate set. Properties, geometry, and relationships are preserved; only the GlobalId string is changed.

Upload the file.
Open the Repair GUIDs tool.
Click Run. The output is a new IFC file with unique GlobalIds throughout.
Re-run Model Health Check to confirm zero duplicates.

Step 3: clean orphaned geometry

Run Clean Hidden IFC Leftovers. Orphans are shape representations, material definitions, and profile definitions that no element references anymore — usually debris left behind when an authoring tool deleted elements without cleaning up the geometry graph. They add file size and can confuse downstream processors.

Step 4: fix storey assignments

If the Health Check reports "elements without storey assignment," open Manage IFC Storeys. The tool lists every element not linked to a storey and lets you assign them by elevation, by proximity, or by explicit drag-and-drop.

Step 5: re-validate

Run Model Health Check one more time. A clean file should show zero critical issues and a much shorter warning list.

When to re-export instead of repair

Some problems cannot be fixed after the fact:

Wrong units in the model (feet vs metres). Re-export from the authoring tool with correct unit settings.
Missing geometry entirely. If the authoring tool exported a wall with no solid representation, no post-export tool can conjure one.
Schema corruption. Files with malformed STEP syntax that will not parse at all. BIMCamel will reject these on upload.

For everything else, the repair pipeline above fixes 95% of real-world IFC quality issues in under a minute. A clean file reflects well on your team and saves hours of troubleshooting for everyone who opens it downstream.