What BIM Coordination Actually Is
BIM coordination is the process of overlaying trade models — structural steel, mechanical ductwork, plumbing piping, electrical conduit, sprinkler systems — in a common data environment (CDE) to detect clashes before anyone picks up a tool in the field. The most common platform is Autodesk Navisworks; Revit, BIM 360 Clash, and Trimble Connect are also common. Clashes found in the model cost minutes to resolve; the same clashes found during steel erection cost weeks and carry significant rework costs.
Level of Development (LOD) Requirements
The BIM Execution Plan (BEP) on your project will specify an LOD requirement for each trade. For structural steel, the common levels are:
- LOD 200 — generalized members with approximate size and location; sufficient for early design coordination
- LOD 300 — specific member sizes, section profiles, and connection type indicated; the standard for construction-phase coordination
- LOD 350 — connections fully detailed including plates, bolts, and clearances; required on complex hospital, lab, or transit projects
- LOD 400 — fabrication-ready geometry extracted directly from the detailing model; the highest standard, sometimes required on design-build projects
IFC Files: The Common Currency
IFC (Industry Foundation Classes) is the vendor-neutral exchange format that lets Tekla Structures talk to Revit, Navisworks, and every other major BIM platform. When your detailer says they deliver 'IFC,' confirm which version (IFC 2x3 or IFC 4) and which IFC type (IfcBeam, IfcColumn, IfcSlab vs. generic IfcBuildingElementProxy). Properly classified IFC objects allow the GC's BIM coordinator to filter and color the steel model by member type, run automated clash rules against specific trades, and generate clash reports that are traceable back to individual pieces.
Clash Types and How Steel Gets Involved
Three types of clashes commonly involve structural steel:
- Hard clashes — steel physically occupies the same space as a duct, pipe, or wall (zero clearance); always a stop-work condition
- Soft / clearance clashes — steel passes within the minimum clearance distance of another system; flagged for review but may be acceptable with coordination
- Workflow clashes — construction sequencing conflicts (e.g., steel erection sequence blocks mechanical equipment installation path); caught by 4D scheduling simulations
What the Detailer's Model Needs to Include
For the steel model to be a useful coordination tool rather than a visual prop, it must include: all primary structural members at their actual section profile; connection geometry at LOD 300+ (plates, gussets, end plates); miscellaneous steel that occupies meaningful space (stairs, mezzanines, equipment platforms); and all embeds and blockouts that affect poured concrete. Omitting miscellaneous steel from the coordination model is the most common mistake — and the most expensive one, because misc steel often runs directly through mechanical rooms.
Coordination Meetings and Who Should Attend
BIM coordination meetings are typically weekly during the construction-document phase. The GC's BIM coordinator chairs; each trade attaches their latest model before the session. From the steel fabricator's side, the detailing firm's project manager should attend or be available for real-time clash resolution. At Tectonix, our U.S. PMs join coordination meetings and can commit to model revisions in the meeting — no international relay required.
Model Updates and the Change Control Process
Once coordination is substantially complete and the model is used for fabrication, changes must go through formal change control. Any structural revision that affects coordination — a beam relocated, a column resized, a new opening added — requires the detailer to update the model, re-export IFC, and notify the BIM coordinator before the revised file is pushed to the CDE. Informal revisions that bypass this process cause outdated model views and missed clashes on the next trade.