Three kinds of clash
Clash detection is often reduced to "find where two things overlap," but a useful workflow recognises three distinct categories. A hard clash is the obvious one: two solid objects occupying the same space, like a duct driven through a beam. A soft clash is subtler — an object that fits geometrically but violates a required clearance, such as the access space around a valve or the insulation envelope on a pipe. A workflow clash is not about geometry at all; it is a sequencing or scheduling conflict between activities.
Treating all three differently is what separates a tidy report from an actionable one. The open data standards from buildingSMART help ensure the models you federate carry the information each clash type relies on.
Setting tolerances that mean something
The fastest way to ruin a clash report is to leave tolerances at their defaults. Too tight and you drown in thousands of false positives where geometry merely touches; too loose and you miss real conflicts. Tolerances should reflect intent — the buffer a trade actually needs — not an arbitrary number. Running tests in a tool such as Autodesk Navisworks with sensible, documented tolerances keeps the list honest.
A clash report is only as good as its tolerances — tune them to what the trades truly need, and the noise disappears.
Group tests by discipline pairs — structure versus mechanical, mechanical versus plumbing — so results are legible and assignable. This grouping is where coordination becomes manageable, as covered in our BIM modeling services.
Issue tracking that closes the loop
Detecting a clash is the easy part; resolving it reliably is the discipline. Every genuine clash needs an owner, a status, and a record of how it was resolved. Without that, the same conflict resurfaces at the next publication and the team loses trust in the report. A lightweight issue tracker — even a shared, structured log — beats screenshots buried in email.
This is the mechanism behind the savings we describe in why BIM coordination pays for itself: tracked issues are resolved issues, and resolved issues never become field rework.
A review cadence that holds
- Publish discipline models to an agreed, repeating schedule.
- Run grouped clash tests immediately after each publication.
- Triage results into hard, soft, and workflow buckets.
- Assign owners and due dates; review open items in a standing meeting.
- Track the trend — the count should fall, not just churn.
A weekly rhythm during active coordination keeps the list shrinking instead of exploding at the deadline. Checklists to run your own cadence are in our free resources.
Frequently asked questions
What are hard, soft, and workflow clashes?
A hard clash is two objects occupying the same space; a soft clash is an object violating a required clearance or buffer such as access or insulation space; and a workflow clash is a scheduling or sequencing conflict between activities rather than geometry.
How often should clash detection run?
Run clash detection on a fixed cadence tied to model publication — often weekly during active coordination — so the issue list stays current and shrinking, rather than as a single late-stage check that overwhelms the team.
Want a coordination cadence that actually clears the list? Request a free quote or explore more in our Insights library.
Cadeonn delivers federated Revit models, clash coordination, and LOD-controlled BIM for architects and engineers serving the U.S. market. Extend BIM capacity without long hiring cycles: request a quote or see BIM services.