Clash Detection Report
The ranked list of geometric conflicts a model check finds, ready for the team to resolve.
Quick Answer
A clash detection report is the output of running clash detection on a federated BIM model. It lists every geometric conflict found — a pipe through a beam, a duct through a wall — classified by type and discipline and prioritized so the team can resolve real clashes and dismiss false ones during coordination.
The Full Picture
A clash detection report exists to turn a raw model comparison into an actionable to-do list. Software can flag thousands of geometric intersections in a federated model, but a naked pile of collisions is useless. The report's job is to organize those hits — by discipline pairing, clash type, and priority — so a coordination team can work them methodically.
Mechanically, clash detection compares model geometry and records conflicts, which the report groups by category. Hard clashes are physical intersections — two solids occupying the same space. Soft (or clearance) clashes are violations of required tolerances, like a valve with no access room. Many hits are false positives — modeling artifacts or intended overlaps — so a large part of reading the report is filtering signal from noise.
In practice, the report drives the coordination meeting. Each real clash is assigned to the discipline that owns the fix, given a status, and tracked to closure, often exchanged as issues through the open BCF format so teams on different tools stay in sync. Clash counts fall week over week as the report is worked, and a near-zero count in the congested zones signals the model is coordinated.
For preconstruction and VDC, the clash detection report is the audit trail of coordination. It shows what conflicts existed, who resolved them, and what remains open before Issued for Construction. A clean report on the zones that matter is evidence the most conflict-prone scopes were de-risked in the model rather than in the field.
Real Examples
Common Misconceptions
People assume: Every clash in the report is a real problem to fix.
Actually: A large share are false positives — modeling artifacts, intended connections, or objects that touch by design. Reading a clash report is as much about filtering noise as resolving conflicts; the raw count matters far less than the number of genuine cross-discipline clashes.
People assume: A zero-clash report means the design is fully coordinated.
Actually: It means no geometric conflicts were detected in what was modeled, at the clearances that were set. It says nothing about unmodeled elements, code compliance, installation sequence, or maintainability. A clean report is necessary evidence of coordination, not complete proof of it.
Does MeltPlan Solve This?
Partially — adjacentPartially — MeltPlan detects and reports coordination conflicts, but from your 2D drawings and specs, not from a 3D federated model. It flags where disciplines conflict or documents are inconsistent and surfaces them for expert review. It does not generate a geometric clash report from a BIM model; if you need model-based clash detection, you'll run that in a dedicated BIM coordination tool.
Surface coordination conflicts in your documents →Frequently Asked Questions
What is a clash detection report?
It's the organized output of running clash detection on a federated BIM model — a list of every geometric conflict found, grouped by discipline pairing and clash type and prioritized. The team uses it to triage and resolve conflicts during coordination.
What's the difference between a hard clash and a soft clash?
A hard clash is a physical intersection — two elements occupying the same space, like a pipe through a beam. A soft clash is a clearance violation, where elements don't intersect but are too close, such as equipment with insufficient access or maintenance room.
Why are there so many false positives in a clash report?
Because software flags any geometric overlap, including modeled connections, intended contact, and modeling artifacts. Much of the work of reading a report is filtering these out so the team focuses on genuine cross-discipline conflicts rather than the raw hit count.
How is a clash detection report used in coordination?
It drives the coordination meeting: each real clash is assigned to the responsible discipline, given a status, and tracked to resolution — often exchanged as BCF issues. Clash counts drop as the report is worked, and a near-zero count in congested zones signals a coordinated model.
Related Terms
More Preconstruction — Design Coordination Terms
- Design Milestone
- Issued for Construction (IFC)
- Design Freeze
- What is Prefabrication Coordination
- What is DfMA (Design for Manufacture and Assembly)
- What is a Trade Coordination Meeting