Direct Answer
IFC (Industry Foundation Classes) is an open, vendor-neutral BIM file format that allows structural, architectural, and MEP models to be shared across different software platforms. Your fabrication project needs an IFC file when the GC's coordination requires model exchange, when the owner requires a BIM deliverable, or when you need to share the steel model with a team using different software.
Full Explanation
IFC files encode geometry, material properties, element classification, and spatial relationships for every building element. An IFC export from Tekla includes every structural member with its section size, material grade, piece mark, and 3D position. This allows Revit users, Navisworks coordinators, and Archicad architects to reference the structural model without needing Tekla. IFC 2×3 is the most widely supported version; IFC 4 is growing. Not all software exports all IFC property sets — verify what properties your downstream team needs.
What This Means for Your Shop
If the GC's BIM requirement includes a structural IFC deliverable, this must be in your detailing contract. Some fabricators discover this requirement late and face delays because their detailer's software doesn't export IFC cleanly.
Common Mistakes
Delivering an IFC file without verifying it loads correctly in the receiver's software. IFC exports from different Tekla versions or with non-standard property sets sometimes fail to load or display incorrectly in older Navisworks versions.
Recommended Process
At project kickoff, confirm with the GC's BIM coordinator: what IFC version, what property sets (AISC members, piece marks, material grades), and what software it will be loaded into. Run a test export with one floor of the model and verify receipt before the full model is complete.