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BIM clash resolution: how we audited an entire building in 2 hours
real story · BIM coordination · IFC · 6 min read
It was nearly 6 pm when we opened the model. Structural had already been reviewed; electrical, plumbing and HVAC remained. By industry standards, the expectation was an all-night meeting. It took us less than two hours.
Before doubt sets in, an important clarification: what we did in two hours was the final system audit, not the modeling. No one coordinates a building from scratch in two hours. And anyone who promises that deserves your suspicion. The two hours only exist because the previous weeks were a rigorous application of the method. When a project is born structured, clash resolution is the final validation of a process that was already aligned from day one.
How reactive clash resolution works (and why it fails)
Most firms work reactively: they model, send the file, receive a clash report with hundreds of alerts and spend days solving problems that could have been avoided at conception. If your IFC export depends on tweaks after modeling, the problem probably started long before the export.
For us, clash resolution is a state of mind, not a final stage. The two-hour audit is the result of three pillars built into the model's structure.
Classification and IFC: the language the model needs to speak
BIM only works if the computer understands what is “structure”, “partition” or “services”. If the element's classification in ArchiCAD is wrong, the IFC (the universal language of clash resolution) comes out compromised. Data integrity begins at the first click.
Rules, not geometry
Treating clash resolution as “checking whether a beam crosses a pipe” is spending physical energy. When you understand that clash resolution is a matter of space-occupancy rules, the process automates itself: if the model follows strict modeling rules, the obvious clashes simply stop existing.
The model as a database
The 3D is the final result, but the intelligence lives in the parameters. When element properties “talk” to each other, checking becomes reading data, not a visual hunt for errors in an ocean of polygons.
what has cost us dearly
It wasn't always like this, and two of our own mistakes explain why we take classification so seriously.
Once, we opened a project with a discrepancy of nearly 100 sq m in the floor takeoff. Nothing was “wrong” in the drawing: one element had been classified incorrectly, and the schedule was adding up what it shouldn't. The model looked right to the eye, but it lied in the data.
In another project, a staircase failed the minimum headroom required by the fire code. The check of the structural model against the head-height projection ArchiCAD itself generates for the stair hadn't been done. The tool was warning us; the process didn't listen.
In both cases, the lesson was the same: the problem was never in the clash report. It was in the foundation of the model.
The right question
If your firm still spends days, or weeks, in clash-resolution meetings, the question shouldn't be “which software do I use to resolve clashes?”, but rather: “which method do I apply so the model is born already coordinated?”
frequently asked questions
How long does BIM clash resolution normally take?
In a reactive workflow, days or weeks, between reports and meetings. In a structured workflow, the final stage becomes an audit of hours, because the bulk of the work was spread throughout the modeling.
What is IFC classification and why does it matter?
It's the information that tells the system what each element is (wall, beam, pipe). Without it right, takeoffs lie and cross-discipline checking loses reliability, as in the 100 sq m case above.
Is clash resolution worth it for small projects?
It is. Scale changes the volume, not the logic. Our method has been applied from 6 sq m to 14,000 sq m, and the reasoning is the same: sound data from the start.
Where is the intelligence of your workflow getting stuck?
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