IFC is the open format for exchanging building models between programs. Exporting one is quick. Knowing whether the file you export is useful to the person who receives it takes more care. A few minutes of checking before you issue a model avoids a round of questions later.

What to look at

  • Is the model what you think it is? Open it in a viewer, not in the program that made it. Missing walls, doors at the wrong level or a model that is far from the origin show up at once.
  • Duplicate GlobalIds. Every element should have a unique GlobalId. Duplicates cause problems when models are compared or merged.
  • Elements outside a storey. Elements that are not assigned to a building storey are hard to filter, schedule and coordinate.
  • Classification. Many projects require that elements carry a classification code, such as Uniclass or OmniClass. Check for elements that have none.
  • Properties. Check that the properties the project requires are present, for example a fire rating on walls and doors.
  • Names. Elements named “Basic Wall 1” or with no name make schedules and coordination harder.
  • Units. The model should use the units the project expects.
  • Georeferencing. If the project uses shared coordinates, check that the model is placed correctly.

A routine with free tools

  1. Open the model in the IFC Viewer. It reads IFC2x3 and IFC4 files in your browser, and the file is not uploaded. Browse the tree by storey or by class, use section planes to look inside and measure a few distances.
  2. Run the BIM Model Checker. Choose the basic profile for model health, the coordination profile for a more demanding check, or write your own rules, such as requiring Pset_WallCommon.FireRating on every wall.
  3. Open each warning to see which elements are affected, show them in 3D and fix the problem in the authoring model.
  4. Use the IFC Property Inspector to browse the property sets and quantities of any element as a table.
  5. Export the report to CSV or Excel and send it with the model, so the receiver knows what was checked.

Fix at the source

If a property is missing in the IFC file, it was missing in the export from the authoring software, or the export settings left it out. Fix the property or the export mapping in the original model and export again. Editing the IFC file by hand does not fix the source model.

What a passing check means

A check reports what it tests for. Passing the checks does not certify a model against a standard or a contract. It means the checked problems were not found. Run the same profile on every issue of the model: the trend from one issue to the next tells you whether the model is getting better.

Keep a record

  • Note the date, the software version and the export settings used for each issue.
  • Keep the check report with the issued model.
  • Agree the required properties and classification with the project team at the start, not at the end.